US1957456A - Method of and apparatus for treating metal castings - Google Patents

Description

S9 SB w. D. HQDSON ET Av.. L957456 FOR TRETNG METAL CASTINGS MkETHOD OF AND APPARATUS Filed Jan. 2?, 195o' 3 V w3 7 i .1\|l1 Il ,m. a A@ 5 C 3a A.. 47 Q 3 u, .f1 A Q Flc.. 2

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Patented May 8,- 1934 t 1 l Y UNITED STATES lPATENT OFFICE METHOD OF APPARATUS FOR TREAT- ING METAL CASTINGS Walter D. Hodson, Chicago, Ill., and Ira J. Simmons, Clair-ton, Pa.

Application January 27, 1930', Serial No. 423,811

Claims. (Cl. 148-2) The invention relates to a method of, and ap- In practicing our improved invention in conparatus for treating metal castings, and more nection with the production of steel, we preferaparticularly to a method of, and apparatus for rebly make use of the cars which carry the molds taining the heat in and equalizing the temperapast the ladle, but our invention is limited to 5 ture in steel ingots or castings after the pouring the use of cars and to the manufacture of steel 60,

operation. only to the extent indicated in the appended The improved method is preferably practiced by claims, as the invention may be practiced in conremoving the mold from an ingot or casting, nection with other metals. after the pouring operation, substantially as soon In Figs. 1 and 2, we have shown cars 4 provided l0 as it has cooled sufficiently to become self-supwith suitable Wheels and adapted to carry stools 65 porting and then promptly placing a thermally 3 and molds 1 past the ladle. The cars 4 are insulating housing or hood over the ingot or preferably provided with apertured platforms casting to retain the heat therein and to retard 4a, the apertures being adapted to receive lugs the cooling thereof so that relatively equal tem- 3a formed upon the stools 3. The stools 3 are peraiures Will prevail thrOlighOlii the ingot 0r preferably formed from metal and are preferably 70 casting after it has been left to soak in its oWn provided with upwardly extending flanges 3b and sensible heat for some time. This treatment re- 3c, the flanges 3c being adapted to hold mold 1 dJCeS the amount 0f pipe that vWill fOlm, and in place upon the stool. It will be noted that the also prevents the formation of the relatively mold 1 rests upon a thermally insulating pad 2 Ierse amount 0f Surface Creeks, oxide, and other which is preferably formed from refractory 75 flaws or undesirable characteristics that result oementitious material, or the equivalent. This from Practicing the methods DOW Widely uSedpad prevents rapid cooling of the bottom of the 'I'he method is preferably practiced With apingot. The flanges 3b are adapted to hold a therparatus comprising a thermally insulating housmolly insulating hood 5 in placeupon the stool ing 01 llOOd, lL:he hOOd being preferably-"f Such when the mold 1 has been removed from the ingot 80 size that there are dead-air spaces between the cast, within the mold, In the drawing, the ingot ingot and the inner Surfaces Of the hOOd. The is identified by the reference character 9. invention permits one to equalize the tempera` The hood 5 preferably comprises an outer shell l ture 0f the DgOi Without placing it in -a heated or housing 7 which is preferablyformed from cast soaking pit before the rolling operation, as is theV iron, or the equivalent for the purpose, and is 85 Dleetiee usually fOllOWed- This effects e Seypreferably provided With lugs 5a to facilitate the A of labor and fuel, and has many other advantages khandung thereof, A lining 6 of refractory t hereinafter Set fOrthcementitious material, or the equivalent, is pref- In the drawing, wherein We have illustrated erably provided within the housing 7 and is prefapparatue embodying e preferred ferm 0f the erably held in place within thehousing by in- 90 invention: wardly extending flanges '7a provided in the base Figure 1 iS a Veteel SeCtOIl thIOllell e Cel' S1110- of the housing. As best shown in Figs. 2, 3 and porting a mold in which an inset has been poured- 4, the outer surface of the lining 6 is preferably Fig. 2iS a Central SeCtiOIl taken through'the apcorrugated to provide a plurality of dead-air .lo params ShOWn in'Fig. 1, the mOld having been spaces 6a between the lining and the housing. 95

TeDleCed by 9J thermally insulating housing, 01' The hood 5 is preferably of such dimensions that hood. a dead-air space 8 is provided around the sides Fig. 3 iS a SeCiSen teken 0n line 3-3 0f Figand top of the ingot 9 when the hood is placed 2, and upon the stool in a manner illustrated in Fig. 2.

4.', Fig. 4 is an enlarged SeCtiOn taken 011 line In practicing the improved method, we prefera- 10U 4 4 of Fig. 2. bly mount a plurality of molds 1 on a like num- At the present time it is common practice in ber of cars 4, in the manner illustrated in Fig. connection with open hearth steel to pour the v1, and the cars are moved past the ladle, each metal into ingot molds which are mounted on load receiving the usual charge of fused metal to cars carried past the ladle, the molds being reform an ingot of the desired dimensions. When 105 movably mounted on a part of the car which the ,ingots have become self-sustaining, we remove is called the stool. As soon as the ingot has the molds l therefrom and place the hoods 5 on cooled sufficiently to be handled the mold is rethe stools 3 in the manner ndicatedin Fig. 2 so moved and the ingot is picked up and placed in that the ingots are thermally insulated by the a heated soaking pit where it is equalized. dead-air spaces 8 as well as by the walls of the 110 fil hoods 5. Thereforethe sensible heat of the ingots is largely retained Within the hoods 5 and the temperatures thereof are equalized by making use of this heat. We find that as soon as the hoods are placed over the ingots contraction of the surfaces ceases for a relatively long period of time as the inner or central parts of the ingots are relatively hot as compared with the outer surfaces thereof and the placing of the hoods over the ingots retards the loss of heat from the surfaces of the ingots to such an extent that they will heat to higher temperatures by heat conducted from the interiors of the ingots. This method of equalizing the temperatures thereof is exceedingly advantageous when compared with the usual practice of normalizing in heated soaking pits. Thus, when the ingots are to be reheated and the temperaturesthereof equalized in a soaking pit they are subjected to the atmosphere before and after they have been placed in the pits. This results in the formation of oxide in relatively large quantities as compared to that which 'forms upon and in ingots which have their temperatures equalized in accordance with our improved method, it being readily understood that when our improved method is practiced the ingots are exposed to the atmos.- phere for an exceedingly short time and the amount of air with which they come in contact is afterwards limited to that in the dead-air spaces 8.

When the temperature of ingots are equalized by the soaking pit method, they contract a relatively large amount before they are placed in the pit, and therefore a relatively large amount of gasl is occluded from them., Then when the ingots expand in the heated pit they absorb much gas which results in oxidation Within the ingots and also results in innumerable small gas filled pockets or holes. These conditions do not obtain when the temperatures of the. ingots are equalized by retaining the sensible heat' thereof during the temperature equalizing process so that it is unnecessary to reheat them;

Another advantage of our improved method is that comparatively few surface cracks form in the ingots, and these cracks do not penetrate to any great depth. Obviously, such cracks are not .as numerous and deep in a finished bar formed from an ingot subjected to our improved method as there are in a bar formed from an ingot subjected to the soaking pit method. Still another and exceedingly limportant advantage of our improved method is that relatively little pipe forms in ingots produced by practicing our method as the ingot-s need not be cooled to a temperature which permits handling thereof as is the practice in the heated soaking pit method. The savings effected through the reduction of pipe when our method is practiced are considerable as our method in itself does not necessitate employing other expedients to reduce the formation of pipe.

Our method is preferably practiced so that the ingots are rolled when they have been cooled to the proper rolling temperature. This practice also effects savings in that it is unnecessary to place the ingots in a soaking pit to reheat them. If the ingots are not to be rolled promptly the hoods are preferably left in place upon the stools until the temperature of the ingots is low enough so that they can be exposed freely to the atmosphere without causing the formation of any appreciable amountof oxide.

We have found that when our method is practiced, it results in a relatively better rolling steel due to the thoroughness with which the temperature thereof is equalized. We have also noted that there is a reduction in the usual loss due to burned steel.

While we have shown and` described certain embodiments of our invention, it is to be understood that it is capable of many modifications. Changes,`therefore, in the construction and arrangement may be made Without departing from the spirit and scope of the invention as disclosed in the appended claims, in which it is our intention to claim all novelty inherent in our invention as broadly as possible, in View of the` prior art.

What we regard as new, and desire to secure by Letters Patent, is:

1. A method of preparing an ingot for rolling which comprises vcovering said ingot with an insulating ho'od substantially as soon as it becomes self sustaining after the pouring operation, and then soaking said ingot solely in its own heat until it cools to an equalized temperature suffi` ciently low for the rolling operation.

2. The method of equalizing the temperature of a metallic ingot having an initial average temperature above a rolling temperature which comprises covering said ingot with an insulating hood of dimensions of the same order as the ingot and having negligible heat capacity, and maintaining said ingot therein until its temperature is substantially equalized throughout and said ingot has reached a rolling temperature.

3. The method of preparing a metallic ingot for rolling which comprises pouring molten metal into a mold,"cooling the metal to a condition of external rigidity and removing the molds and immediately covering the ingot with an insulating substantially airtight hood, maintaining the ingot beneath said vhood until the temperature of the ingot is substantially equalized throughout -and said ingot has cooled to a rolling temperature.

4. The method as s'et forth in claim 3, in which said hood has a negligible heat capacity.

5. The method as set forth in claim 3, in which 'the ingot is not removed froml its initial base throughout the operation.

WALTER D: HoDsoN. IRA J. SIMMoNs. A

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