US2348199A - Ladle for molten metal and method of sealing closures therein - Google Patents

Description

G LosuREs THEREIN H. G. FREEMAN May 9, 1.944.

LADLE FOR MOLTEN METAL AND METHOD OF SEALIN Filed Oct. 20. 1945 nsv INVENToR. H. G. FREEMAN BY @UMA YVewlga) ATTORNEY.'

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Patented May 9, 1944 UNITED STATES. eTENT oE-ElcE;

LADLE FOR MOLTEN METAL AND METHOD F SEALING- CLQSURES THEREIN Henry G. Freeman, Granite City, Ill.

Application October 20, 1943, Serial No. 507,222

Claims.

This invention relates to ladles for molten metal and methods of sealing closures therein. Ladles of this kind are employed to carry molten metal from one location to another in a foundry or the like. The ladle is usually provided with an outlet nozzle in the bottom thereof and a stopper to control the iiow of molten metal through the nozzle.

In many operations the molten metal is retained in the ladle for relatively long periods of time.l For example in the treatment of certain types cf metals, the molten metal may remain in the ladle for twenty to forty minutes. Under these and other conditions, it has been found that the molten metal around the stopper congeals or freezes, thereby preventing free movement of the stopper at the outlet nozzle.

Whenever, the molten metal congeals around the stopper, it is diiicult, and dangerous, to remove the stopper from the nozzle. Frequently, in the eiorts to free the stopper from the nozzle the operating mechanism for the stopper is broken, requiring relatively costly repairs. Moreover, whenever, a stopper is forcibly pulled away from congealed metal, this metal around the nozzle and on the stopper, tends to prevent effective closing of the stopper, thereby permitting the highly heated molten metal to continue to ow from the nozzle. This undesirable ow of molten metal not only results in waste, but is a source of serious danger to workmen adjacent to the ladle.

To my own knowledge, the foregoing conditions have existed in large scale commercial procedures for the past twenty years. An cutstanding factor of this perplexing old problem appears in the fact that ordinary ladles contain many tons of highly heated molten metal, for example 60 tons, and the generally accepted methods of forcibly releasing the Stoppers involve serious risks of personal injuriesto the operators, as well as Very substantial economic losses.

An illustration of a common practice appears in the use of' a rod or bar inserted into the bottom of the dischargenozzle to forcibly displace the stopper from its seat. The lower end of this bar is heldk in Contact with a rigid abutment, such as a large plank or the upper edge of a mold, while the crane which supports the ladle is operated to lower the ladle onto the rod or bar in the discharge nozzle. The weight of" many tons is thus manipulated to pushthe stopper from its seat, and when this occurs, there is a sudden and uncontrolledV rush of molten metal, under high pressure, through thcdischarge nozzle. A

large percentage of the molten metal is immediately splashed in almost all directions, instead of being discharged into ,a mold, and in actual practice, this commonly used expedient involves the presence of persons dangerously close to the uncontrolled stream of molten metal.

Therefore, an object of the present invention is to provide a simple and eilective means for eliminating said hazards and loses. More specifically stated, an object is to create an entirely feasible and inexpensive method of positively excluding molten metal from the lower end portion of the stopper which contacts with the discharge nozzle. A further object is to produce a condition wherein the molten metal near the stopper is insulated from the relatively cool air in the discharge nozzle, thereby overcoming a condition which usually causes the molten metal to freeze or solidify at thestopper.

In the preferred form of the invention, these objects are accomplished by separating the lower end portion of the stopper .from the hot zone of the molten metal, and forming a sealing crust abovethe nozzle and around the stopper, so as to positively exclude the molten metal from vsaid end portion of the stopper.

With the foregoing and other objects in view, the invention comprises the novel method/and the construction, combination andy arrangement of parts hereinafter described and illustrated in the accompanying drawing. However, it is to be understood that the invention extends to modifications and variations within they scope of terms employed in the claims hereunto appended.

Fig. 1 is a side elevation, partly in section, illustrating a ladle for molten metal having a cavity at the bottom to receive a stopper.

Fig. 2 is a fragmentary section on a larger scale, showing the lower portion of a stopper sealed from the zone of the molten metal'.v

Fig. 3 is a top View oi a sealing crust around the stopper, showing portions of the bottom of the ladle around the crust.

The ladle shown in the'rdrawing comprises an,

outer metal shell 4, and a refractory brick vlining 5 having a coating of refractory c1ay`6` `en its inner face. Asshown in Fig. l the'A ladle isf'open at the top to receive molten metal, suchas steel. The bottom' f the ladle is provided with a tubular nozzle 'lffor the discharg'eof molten'metal from the ladle. f

The nozzle l, which is preferably made of a refractorymaterial, islocated in anv opening at thebottom-of thell'adle, asshown inlllig.v l.j The lower portionof thehozzle 1 projects beyond the 23 shell 4 and is provided with a shoulder 8 seated on a plate 9. This plate 9 is secured to the bottom of the shell 4 to prevent downward displacement of the nozzle.

As an illustration of a means for controlling the discharge of molten metal through the nozzle 1, I have shown a long vertical stopper including a head Ill at the bottom movable into and out of engagement with a beveled seat at the upper end of thenozzle ,1.

The stopper head I may be made of refractory material, such as graphite. This head II)V is secured to the lower end of a metal rod I I which extends upwardly through the open top of the ladle. To protect the rod I I from the intense heat of the molten metal, the portion ofthe rodflocated in the ladle is surrounded by a plurality of refractory sleeves I2. The upperv portion of the rod II is threaded to receive a nut I3 which securesthe sleeves I2 on the rod.

I will now refer tothe operating means for movling the stopper head I0 into and out of engagement with the beveled seat at the inlet of the nozzle 1. A bar I4 is slidably mounted in guides 15,16 and I1 which are securedto the outer face of the shell 4. -The -upper portion of the bar I4 extends laterally over the ladle, and is secured to the rod I I by means of nuts I8. It will be understood-that by imparting' an upward motion to the barl, the refractory head I0 will be raised olf its y'seat to permit the discharge of molten metal from the ladle. Thereafter, a downward movement of the bar I4Vwill again seat the head IIJ to stop the flow of molten metal.` f

i The means for raising and lowering the bar I4 includes a lever I9 pivoted at 2to the lower guide I1; 'The lever I9 has a rounded end portion 2| extending into an opening 22v in the bar I4. The other end of the leverV I 9 is provided with a handle 23 for imparting motion through the lever I9 to the bar I4; `The ladle herein described is of a type in general use in foundries or the like,.so I do not deem it necessaryito showmany of the usual detailsV of construction. y

It has long been knownLin; this art that the molten metal inY aladleY ofjthevtype herein -disclosed has a tendency to solidify or freeze at the outlet nozzle, especially when the moltenmetal remains in the ladle for arelatively long period of time. This' solidication of vvthe metalrat the outlet nozzlek VeryIrequenly prevents or interferesrwith theproper operation of the stopper I0.' Prior to my inventions, those skilled in the arthave failedtosuccess'fully overcome this perplexing condition. k Y Y I have observed that vundervordinary conditions, the relatively ,cool air entering through the outlet ofthe nozzle `tends to Acool the stopper head and upper portion of, thenozzle, thereby Vtending to solidify the adjacent moltenmetal. Il have also found that by creating the special conditions herein disclosed, I canV positivelyeliminate the ris1 o.f.rs91difving metal; at the bottom. 0f .the Stopper- ,K Y Y Y. vIneactual use vof theinvention in a fullsize ladle,V having a capacity Vof about 6o tons A o f molten/steel, I employed conveniently available, inexpensive,moist loam to forma flaring cavity 24 which extends upwardly fromr the top of the nozzle 1. A mass of this moist, loam 25r was tamped into the bottom of the ladle, around the nozzle 1, andthen shaped to form a beveled surface whichlaresupwardly from the beveled seat at Athe ton of .said nozzle.-1`his shaped massof moist loam 25 was heated by a gas flame to remove moisture therefrom, while hardening the loam to provide a firm beveled face at the top, adapted to guide the stopper head I0 to its seat on the top of the nozzle 1. The stopper was then forced onto its seat to produce the condition shown in Fig. 1.

I then introduced a mass of dry sand 26 into the flaring cavity 2,4, around the lower end portion of the stopper. This dry sand may be gently packed into the cavity, merely to close excessive voids between the grains, and if any of the sand escapes through the discharge nozzle, the oper- A ator will vadjustA theA stopper to avoid subsequent leakage 'of molten metal. Since this sand is dry, it does not require heating to remove moisture.

However, the sand is loose, and in the absence of a hrml confining closure, it would be scattered throughout molten metal which is thereafter forcibly introduced into the ladle. In other words, the dry*V sand V26v would be displaced from the cavity, and the molten metal would then contact directly. with the lower portion of the stopper, at the top of the discharge nozzle 1.

Therefore, before introducing the molten metal into the ladle, I formed a sealing layer'of relatively hard crust 21 on the mass yof sand 26 and around the lower end portionof the long stopper. To produce thisv crust 21, I gently tamped the common,r conventional, and inexpensive moist loam onto the dry sand, and smoothed the top face thereof, so; as tov provide a top surface approximatelyflush lwith the top of the flaring cavity 24, and likewise approiu'mately flush with the usual refractory coating 6 in the bottom of the ladle. These operations produced a weak, moist seal, separating the lower end portion of the stopper from the hot zone of the molten metal.

I realized that the moisture in the seal would produce asudden explosive vforce if exposed to highly heated molten metal, and that a suitable seal should be relatively hard and firm to resist the forces of the incoming molten metal, and that the seal should not be free to float in the molten metal, Therefore, the moist seal vwas heated for a few minutes-by theV commonly available gas flame, thereby convertingit into a dry, hard sealing crust 21, nicelyvanchored in the top of the cavity 24 and around the lower portion of the stopper. Many tons o f Ymolten metal was then introduced into the ladle, without rupturing the firm crust 21. This crust positively separated the molten metal from the closure seat in the bottom wall' of the ladle. ItA also resulted in an insulating value, tending to prevent the usual cooling which occurs when 'the molten metal Alies adjacent to coolf atmospheric "air" in the discharge nozzle 1.

Furthermore, the sealing'crust did not interfere with the expectedregulated Adischarge of molten metal vfrom the ladle. This crust' was very readily broken by impartingh the usual forcible lifting movement to the stopper, so. as to discharge the molten metal through thenozzle 1.

In the-foregoing description Ihave referred to numerous specific conditions actually employed in successful largel scale tests, wherein I employed the most convenientv and inexpensive materialsV available at the place where the tests were conducted. However, it is to be understood that the scope of the patent is not limited to these specific conditions. For. example, any suitable means may be employed to form a discharge port, instead of usingthe tubularL nozzle 1. and the .cavitvztcanbe formed many suitable manner and may be of any desired shape. Instead of usingV dry sand at 26, one may more conveniently employ loose dry ashes, dust, dirt, or other suitable comminuted or granular material, surrounding head l of the stopper. Such material, or other heat resisting material, sealed in a cavity around the closure, is very desira-ble but not essential to success of broader aspects of the present invention.

The sealing crust is a more important factor, as it is the element which insures a separation of the closure seat from the hot zone of the molten metal. This crust can be very economically formed by the usual moist loam without resorting to the trouble and expense of arranging for special materials. However, so far as the present invention is concerned, it could be formed by any other suitable heat-resisting refractory material, including graphite, mortar, Portland cement, or mixtures of other materials, preferably but not essentially applied to the ladle in a plastic state to form a close-fitting moist seal, and then baked to form a dry, hard crust between the closure seat and the hot zone of the molten metal.

I claim: 1. In the art of transmitting molten metal through a ladle having a discharge port at the 'bottom and a stopper provided with a closure at the bottom to be seated at said discharge port, the method of separating the lower end portion of said stopper from the hot zone of the molten metal which comprises forcing said lower end portion of the stopper onto its seat at said discharge port, forming a seal of moist plastic material at the bottom of the ladle, above said seat and around said stopper, heating said plastic material to remove moisture therefrom and at the same time convert it into a'relatively hard crust, thereafter pouring molten metal into the ladle, said crust being between the hot zone of the molten metal and the lower portion of the stopper, and subsequently breaking said crust by imparting a lifting movement to said stopper, so as to release the molten metal.

2. In the art of transmitting molten metal through a ladle having a discharge port at the bottom and a manually operated stopper provided with a closure at its'lower end to close the top of said discharge port, the method of separating the lower end portion of said stopper from the hot zone of the molten metal which comprises, forming in the bottom of said ladle a cavity eX- tending upwardly from said discharge port, forcing ythe lower end of said stopper onto a seat at the upper end of said` discharge port, introducing a mass of dry particles into said cavity and around the lower end portion of said stopper, forming a layer of moist loam on said mass of dry particles and around the stopper, to seal said drymaterial and the lower portion of the stopper in said cavity, heating said layer of moist loam to convert it into a sealing crust, thereafter pouring molten metal into the ladle, and subsequently breaking said sealing crust by imparting a lifting movement to said stopper, so as to discharge molten metal through said discharge port.

3. In the art of transmitting molten metal through a ladle having a, discharge nozzle at the of said flaring cavity.

bottom and a manually operated stopper provided with a closure at its lower end to close the top Vof said nozzle, the method ofseparating the lower end portion of said stopper from the hot zone ofthe molten metal which comprises, forming in the bottom of said ladle a cavity immediately above said nozzle, forcing the lower end of said stopper onto the upper end of said nozzle, introducing a mass of separatingv material into said cavity and around the lower end portion of said stopper, forming a layer of moist plastic material .on said mass of separating material'and around the stopper, to seal said separating material and the lower portion of the stopper in said cavity, heating said layer of moist plastic material to convert it into a 'sealing crust, there' after pouring molten metal into the ladle, and

subsequently .breaking said sealing crust by imparting a lifting movement to said stopper, so as to discharge molten metal through said nozzle.

4.l In the art of transmitting tons of molten metal through a ladle having a discharge nozzle at the Ibottom and a manually operated stopper provided with Va closure head at its lower end to close the top of said nozzle, the method of separating the lower end portion of said stopper from the hot zone of the molten metal which comprises, tamping a mass of moist loam into the bottom of said ladle andA around said nozzle, shaping the top of said tamped moist loam to form a flaring cavity extending upwardly from the top of said nozzle, heating said moist loam to remove moisture therefrom, forcing the lower end of said stopper onto the upper end of said nozzle, packing a mass of dry granular material into said flaring cavity and around the lower end portion of said stopper, forming a layer of moist loam on said mass of dry granular material and around the stopper, to seal said dry material and the lower portion of the stopper in said cavity, heating said layer of 'moist loam to convert it into a sealing crust, thereafter pouring tons of molten metal into the ladle, and subsequently breaking said sealing crust by imparting a forcible lifting movement to said stopper, so as to discharge molten metal through said nozzle.

5. In an apparatus for conveying tons of molten metal, a ladle having a discharge nozzle at the bottom, a manually operated stopper provided with a closure at its lower end to close the top of said nozzle, and means for sealing the lower end portion of said stopper from the hot zone of the molten metal which comprises, a flaring seat extending upwardly from the top of said nozzle to form a flaring cavity above the nozzle, the lower end of said stopper being seated upon the upper end of said nozzle, a mass of dry granular material located in said flaring cavity and around the lower end portion of said stopper, and a hardened crust of refractory heat-resisting material located on said mass of dry granular material and around the stopper, to seal said dry material and the lower portion of the stopper in said cavity, said stopper being movable upwardly to break said crust and release the sealed contents HENRY G. FREEMAN.

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