US1455197A - Ingot mold and ingot - Google Patents

Description

May 15, 1923.

' E. GATHMANN Filed July l5. 1922 remita May' is, reas.,

attain are,

EMIL GATHMANN, 0F BALTIMORE, MARYLAND.

INGo'r MOLD AND meer.'

Application led July `15, 1922. Serial No. 575,312.

To all t may concern `Be-it known that I, EMIL GATHMANN, a citizen 'of t the United States, residing in Baltimore city, State of Maryland, have invented certain new and useful Improvements in Ingot Molds yand lngots, of which the following is a specification.

This invention relates to the casting of ingots from eil'ervescing or gassy steel and 1t involves certain improvements in the construction of the mold and in the method of manufacture.

The improved mold is illustrated in the accompanying drawings which show a vertical section of a metal ingot ymold embodying my improvements.

VThe major part A of the mold is of the well known Gathmann type shown in patents heretofore granted to me, of which my latest Patent No. 1,419,454 of June 13, 1922, may be taken as an example. Such molds are usuall bi end up molds constructed to cool t e mo ten metal more quickly in the lower portion of the mold than'in the upper portion thereof as by making the lower mold walls thicker and of greater heat absorbing quality. In such molds, in order to reduce piping, provision has been made to conserve the heat of the ingot at its upper end as by making the mold walls thinner at the topor by providing heat insulating means for the upper portion of the ingot. The part A is formed, as shown, with a bottom opening a closed by a plug a and `a sealing plate a2 of the kind shown in my patent of June 13, 1922. The mold walls are rounded or necked in at a as also'shown in said patent. The part A of the mold is formed with lugs a3, a4 by means of which it may be lifted or supported while being raised or transported.

Instead of employing a top section of refractory material as -heretofore to conserve the heat of thewtop portion ofy the ingot,- I employ, according to my present invention, a metallic mold top portion T which is adapted to chill the upper part of the ingot by absorbing the\heat therefrom for a purpose hereinafter described. This top portion is flanged at t to provide a part which eX- tends to a slight distance into the lower mold section and a part t which rests on the top of the mold section A, as shown in my patent No. 1,192,617 of July 25, 1916. l

Molten'steel, as it is teemedi'into the ingot forming mold, in so far xas freedom from oecluded gases is concerned, may be broadly separated into two kinds. These are generally known as effervescing or gassy steel and .none'ervescing or deoxidized steel.

My present invention relates primarily to ymeans for more eiicientlyproducing ingots made of gassyor elfervescing steel, 1. e., steel containing a large volume of gases in solution due to the oxidation of the meta-l in the melting process carried on in Bessemer converters, open-hearth furnaces and similar melting apparatus, and where the steel has not been fully finished or deoxidized before it is poured into the mold.

During the cooling and solidiication of the ingot in a mold; the contained gases are released as the cooler metal does not have the same absorptive or solvent power for the gases as it has when at a higher temperature andk while being poured into the mold. As the ingot metal in the mold cools towards the critical line of solidication or so called lfreezing, the contained gases are released from solution with the metal and as the ingot metal becomes pasty or partially solidified these gases are entrapped in the body of the ingot metal within the mold and at times cause the metal to 'boil and if means are not provided to freeze over the open or free surface at the top of the ingot, the volume of the ingot would at times be materially enlarged bythe formation of numerous blow holes or gas pockets of varying sizes principally within the zone of the outer skin of the solidifying or pasty ingot. It has, therefore, been the common practice to .freeze over the upper exposed surface of the ingot when made of gassy steel at an early stage of solidiication. Such freezing as previously practised has, however, not been sufficient to prevent a considerable increase in volume or a greatenheight or length of the solidifying ingot as the chilling action has heretofore 'type of steel. In steel well deoxidized, a

decrease in volume is ell'ected amounting to from three to six per cent or more during the process of solidication. This latter kind of solidification has been so controlled by casting the molten metal of this type in ingot molds of the'kind shown, for instance, in my prior (patent of June 13, 1922, that the pipe or iscard is contained in the upper 3% to 8% of the ingot. From analyses of tests made by me it has been shown that a 'big end up mold, i. e., one with a larger cross section at the upper end,limproves the quality of the ingot produced therein not only in thoroughly deoxidized steel but in the far larger tonnage field of ingots which are now being produced of gassy or effervescing steel. I have found, however, that a refractory shrink head for conserving the heat of the ingot at its upper portion, such as I have used when working with well deoxidized steel is not efficient in the production of ingots made of gassy steel. Therefore when working with `gassy steel I have avoided conserving heat at the upper end of the ingot and instead provided means for chilling this portion of -the ingot. The meanspreferably used for this purpose 1s what may be termed a chill top. This is adapted to contain a greatly reduced section of the upper portion of the gassy steel ingot. yThe chill top referred/to is illustrated in the drawings at T. It consists of a heavy heat absorbing mold portion having aY chamber of materially contracted cross sectional volume or area relatively the average cross section of the body of the `ingot being formed, whereby the upper end of the ingot is chilled by the rapid'absorption of its contained heat by the top mold section. In this way the upper portion of the ingot is made to solidify much .more

quickly than the body part thereof.

The top chill section shown is of such construction that it may be readily applied to or removed from a mold and does not involve complicated apparatus for moving it.

rIlhe rapid freezing' or solidiication of the top of the ingot prevents or at least greatly retards or reduces the swelling or enlargement of the ingot body and the consequent 4Jformation of numerous blow holes which cause such swelling in ingots made in the usual way. y

Such blow holes as are formed in the ingotmade in accordance with my invention are deep seated, i. e., locatedV at a considerable distance from the surface of the side walls of the ingot. Actual tests have'shown that most of the blow holes are contained in the top or u per portion of the ingot which has been chi led and frozen by the chill top section of the mold.

The so called big end up mold when fitted with my improved metallic mold top for chilling'and rapidly solidifying the top and upper side 'portions ofthe ingot permits of the use of a much larger percentage than heretofore of the entire ingot for commercial purposes, such as sheet, bar, structural steel, and other steel products where the surface conditions are of primary importance. The entire body of an ingot formed in a mold having a chilling section of the kind shown in the drawings may be utilized with the exception of approximately one-half of one per centor less discard at the bottom of the ingot and approximately o-ne and a half to three per cent at the top of the ingot for steel product where surface is of primary consideration and uniformity of interior condition is not of great importance. The decrease in the top cross section of the ingot as also in the base portion as produced in my improved lmold largely preventsor reduces the splitting of the ends of the ingot during the blooming or slabbing operations in the` rolling mills.

In the ordinary iiat bottom type of ingot mold from 2% to 3% of the ingot is lost due to the so called fish tailing or splitting of the ends during rolling, but by providing the mold with a rounded bottom as shown and heretofore described and with a contracted top adapted to chill the top of the ingot, the'total discard in the rolling process due to fish tailing or splitting is greatly reduced.

The drawings illustrate diagrannnatically the appearance of the blow holes formed during solidication, and it will be pbserved that these are largely confined to the top part of thel ingot within'the chill section of the mold. The shape of the ingot ends formed as heretofore explained is such that relatively small cro at each end yis required. The blow ho es shown in the body of the ingot diagrammatically are not injurious, for product where surface 'is of prilnary importance.

It should be observed that inv order to get the best results the 4cross sectional area of the upper portion of the mold-chamber or chill head should be less than half the mean cross sectional area of the body` of the chamber portion of the mold. The top portion of the mold or chill head should have its walls contracted to surroundl at least one-tenth of the length of the ent-ire ingot and the walls of said top portion should be of greater weight and volume than the weight and volume of that portion of the ingot which is cast within it and the side walls defining the lower chamber portion should have a downwardly in'- clined inwardly extending necked-in contour to reduce the cross section at the' bottom of the ingot.

I claim as my invention:

1. An ingot moldhaving a metallic heat absorbing top portion adapted to form the upper part of ingot and to be removable from the main body of the mold and conl structed` to chill and thus quicklyy freeze lthe upper part of the ingot.

2. A big-end-up ingot mold having a metallic heat absorbing top portion adapted to formthe upper art of the ingot and to chill and thus qulckly freezesaid upper portion.

3. A'big-end-up metallicl ingot mold hav ing the walls of its lower portion constructed or equipped to promote the cooling of the lower' part of the ingot, and having an all-metallic top part constructed to form the upperend of the ingot and to rapidly chill saidupper part during solidification to thus assemble blow holes lat the top of the ingot. s,

4. An ingot mold having a rounded bottom and rounded lower side walls adapted to rapidly cool the lower part of the ingot and having a top portion constructed to form the upper end of the ingot and .to chill said upper end rapidly during solidification. I

5. A metallic ingot mold provided with a necked-in or round bottom and having a vertical chamber, the cross sectional area of the upper portion of which is less than one-half of the mean cross sectional area of the body of the chamber.

6. A metallic ingot mold having a contracted upper chamber constructed to hasten the chill and thus freeze the'upper portion 'of the molten liquid ingot more rapidly than the freezing of the body portion of the ingot, said mold chamber beinglprovided with a necked-in or rounded bottom whereby both the top portion and )the bottom portion of theingot will be of less mean cross sectional area than the mean cross sectional area of the mold chamber.

An ingot mold having its top ingot forming chamber portion defined by metal lic walls, said top portion having a mean cross section of less area'than the mean cross sectional area of the vertical mold chamber,

the said chamber being provided with a b ottom or base portion having a. rounded or a COIlCaJVO-'COIIVGX COIllJOllI'.

8. A metallic ingot mold provided with a concavo-convex bottom or base portion and having a metallic heat absorbing top portion 4inclosmg a vertical chamber adapted to form -the upper part of the ingot and constructed to chill and thus quickly Jfreeze the vertical walls of thevupper part of the ingot.

9. An ingotmold having its ingot forming chamber defined by heavy metallic ,heatabsorbing walls, the top and also the bottom portion of the ingot chamber having an area of less horizontal cross section, as defined by the metallic heat absorbing walls, than that .of the body portion of said chamber, and the side walls defining `the lower chamber portion having a downward inwardly extending necked-in contour terminatingin 10. An ingot mold having its ingot forming chamber defined by heavy metallic heat absorbing walls, the top and also the bottom portion of the ingot chamber having an area of less horizontal cross section as dened by the said metallic heat absorbing walls than that of the body portion of said chamber, and a. separable base portion for closing the lower portion of the ingot chamber.

1l.v vertically extending ingot mold having substantially its entire ingot forming chamber defined by heavy metallic heat absorbing walls, the upper as also the lower portions or sections of said chamber having a necked-in contour, whereby an ingot formed in said chamber will have its top and bottom ends of less horizontal Across section than the body of the ingot.

l2. A mold for forming and' rapidly chilling ingots which are made of a gassy or partially deoxidized molten metal, the said mold beingY characterized by having its vertically extending and also its bottom Wall portions defining the mold chamber constructed of heavy metallic heat absorbing material, the upper and lower sections ot said chamber having a mean horizontal cross sectional area considerably less than that of the body portion of said chamber.

13. An ingot cast in` a chill mold throughout its length and having a top and bottom portion of less horizontal cross sectional area than that of the intermediate. body portion of the ingot, the base surface portion being substantially flat and merging into the lower portion of the ingot by means of a necked-in contour. y

14. An ingot produced from a gassy or partially deoxidized molten metal cast in a chill mold throughout its vertical length, having a top and bottom portion of materially less horizontal cross sectional area than that ofthe intermediate body portion of the ingot, the base of the bottom portion of the ingot being formed or defined by a relatively thin flat metallic late, which is welded orattached to the said base by the casting of the said ingot.

15. An ingot produced from gassy or partially deoxidized molten metal having its lower, its body and its vertically extending f top portions formed in an ingot moldcham- `ber defined by heat absorbing metallic walls,

the lower and the top portions of said ingot having an area of less horizontal cross section than that of the body portion of the ingot and the side walls defining the lower portion of the ingot havln Vlili IiP/0 splitting or fshtailing of thel upper and lower end portions of the ingot during: its blooming or slabbing in the rolling mill is reduced, Which consists in accelerating the isolidification of the upper and ,lower ingot portions by means of upper and lower heavy chambered chills each of which is of less cross sectional area than the middle portion of the mold chamber therebymolding the said upper and lower portions of the ingot in seid chill with less mean cross sectional area. and less transverse dimensions than that of the body of the ingot.

In testimony whereof, I have hereunto subscribed my name.

EMIL Giifrrnmim`

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