US2398768A - Exothermic reaction charge - Google Patents

Description

April 23, 1946. c. A. CADWELL EXOTHERMIC REACTION CHARGE I INVENTOR. CHARLES A. CADWELL BY M, 6

+19 ATTORNEYS ad/ Patented Apr. 23, 1946 Charles A. Cadwell, ClevelandQOhio, assignor to. The Electric Railway Improvement Company, Cleveland, Ohio, a corporation of Ohio Original application January 13, 1941, Serial No.

374,229. Divided and this application Novem- "her 30, 1942, Serial N0. 467,340

3 Claims. (Cl. 75-457) In the use of exothermic reaction mixtures, and particularly in the use of mixtures such as are employed in the well known alumino-thermic reaction to produce molten metal, one of the problems encountered is the proper disposition of J the charge in the crucible. For example, where it is desired to produce molten copper by such reaction, the charge may comprise aluminum powder admixed-with copper oxide in addition to other minor ingredients. It is also necessary to provide an ignition powder on the'upper or exposed surface of the charge whereby the latter may be readily set on. Once started, of course, the alumino-therrhic reaction is quite rapid and 'may even become violent due to the large amount of heat given off.

However thoroughly the ingredients of the charge are intermixed previously toplacein'ent in the crucible, I have found there is a'tendency for such ingredients to segregate, when simply poured into the latter, due to differences in shape and specific gravity of the particles, and unless this be controlled, the charge will not fire uniformly. This is particularly objectionable in the case of a small charge, as required For this and analogous uses of the aluminothermic reaction, I have found it desirable as 'set forth in my prior Patent No. 2,229,045, dated January 21,1941, to utilize an alumino-thermic reaction mixture in which instead of powdered aluminum a powdered copper-aluminumalloy is employed, the effect of which is to reduce the violence .of the reaction when the chargeis ignited. Also, as setforth in said 'priorpatent, the charge is desirably madeup'in package or cartridge form so that the precise amount required for a particular operation may be deposited in the crucible which forms anassociated part of the mold employed bonding operation. Even where, as prescribed, such. car.- tridge, following removal of the. cap whichcloses one end, is quickly inverted into the crucible and thenwithdrawn, a certain amount of segregation is apt to occur, with the result that when ignited the charge may not react uniformly or in its entirety. I 1 y,

The object of thepresent invention, accord.- ingly, is to provide an. improved method of charging a crucible with material for producing molten metal by exothermic reactionwhereby such-material will be deposited in the crucible in a condition which will conduce to a uniform and complete reaction. At the same time the convenience of having a material available in packagefor cartridge form is retained. v I I To the accomplishment of the foregoing and related objects, the invention, then, consists of the steps hereinafter fully described and particularly pointed out in the claims. p The annexed drawing and the following description set forth in detail certain steps embodying the invention, such disclosed stepsl con- 'stituting, howe'ver, but, one of various ways in which the principle of the invention may be use d. H g

In said annexed drawing: r Fig. 1 is a transverse sectional view of an apparatus for rail'bonding, such apparatus includ ing a mold and associated crucible for, the production of molten metal by exothermic reaction; Fig. 2 is a perspective view ofa cartridge used in packaging the charge; v

Fig. 3 is a central section of such cartridge showing disposition of its contents;

Fig. .4 is an elevational view of a crucible adapted for use in my improved method, such crucible beingdesigned for pouring the resultant molten metal instead of discharging the same directly into an associated mold; and V Fig. 5 is a transverse section of such pouring crucible, the plane of the section being indicated by the line 5 -5, Fig. 4. g

Referring to the rail bonding apparatus illustrated in Fig. 1, this will be seen to comprise a suitable frame] (shown only in part) which is I adapted to rest upon ,the top of the rail head 2 ,andsupporta graphite mold block 3. The lower ".portion ofrsuch block is desirably encased in a close fittingmetal shell l through which passes a pin. 5 whereby the blockis pivotally mounted in a clevis 6. "Such clevis is in turn supported in frame I by means of a bolt 1 which passes through a boss 8 on such frame, and a leaf Spring 9 is, attachedto the frame by the same bolting jmeans and is interposed between said clevis and mold to resiliently bear upon the face of the mold opposite its rail-engaging face. It will be understood that frame I includes clamping means which engage with the rail head and re tain the frame against transverse movement relatively to such head, so that the result of the action of said spring 9 is to retain the mold block closejfi tting contact with the rail head, e mold block which is of refractory material; preferably graphite, has a mold cavity l9 connected byway ofa sprue passage 20 with the self-positioned in the bottom of the crucible,

Attached to the top of the vblock 3 in which crucible 2| is thus provided, is a cover 23, such attachment being preferablybymeansof a hinge 24 so that the cover may beatilted clearfiof the' crucible when it is desired to have access 'to the latter. Such cover arches upwardlyover the crucible and is provided with-a-ventaopening25 centrally thereof, and so coaxial with the cruelble, and this opening is in turn surrounded by an upwardly extending slightly flared rim 26.

Rim26 on the'crucible cover-is designed to receive-and ensure proper placement of a cartridge 21 in which the charge of reaction materials is packaged. As better shown in:Figs. 2 and 3, this cartridge comprises a cylindrical container, e. g. of cardboard, permanently closed-at one end as by a cap 28 and having aremovable cap 29 at its other end. In filling such-cartridge the re quired amount of .igniting powder .30 is first placedtherein and vthen the cartridge is filled 9 withthe main. body .3 IV of the'charge, such as the previously describedlmixture of comminuted copper oxide'and copper-aluminum-alloy. in proper proportions. In utilizing the cartridge 21.just described, to charge the crucible in the apparatus illustrated in Fig. l, theCap 29is removed and the cartridge is placed in an. inverted, position in the upper rimmed portion of the cover 23, as illustrated in dotted. outline in Fig. 1. The open end of the cartridgeis thus seated directly over the central opening 25 which communicates through the. cover withthe interior of the crucible.v

As a result the contents of the cartridge will be centrally discharged'in the form of a'cylindrical stream against the bottom of the cruciblecharnbeer and then pileup and expand against the crucible wall by a shearing and rolling action of the particles which producesa filling with the finer parti'cles and dust predominating alongthe;

axis of the crucible and the coarser-particles against the wall. ,The'upper surface of the chargefl32, as thus placed in the crucible .willbe slightly mounded, as shown in Fig. l.

The ignition powder, originally in ,the bottom, of the cartridgewill now be, on top of the, .charge' in the crucible, properly disposedto be ignited. This maybe doneb dropping a match through theopening 25 following.remova1 of the empty cartridge or by means of a spark gun discharged through such opening.

Upon ignition, the center of the fiery crater accompanying the reaction follows down the center column of finer particles whichreact more slowly than the coarser grains and by so doing ive thelatter time to roll into the fire, all to the end that uponcompletion of thereaction when the break through takes place, the .metal is discharged as a hot shot rather than as a stream which may under the most adverse circumstances be atricklingstream. s

It is readily seen thatchargingthe crucible by pouring of the cont'e'nts from an obliquelposition of the cartridgemay result in areaction crater that descends along a tortuous-path, perhaps --reaction of thechargewill melt thegate 22 instantly upon coming in contact therewith, and

dropping downwardly through sprue opening 20 will-collectdn the mold cavity IS in which the terminal portion 32 of the bond which is to be 'weldedrto therail head 2 is held in proper positionby means ofgripper fingers 33. The result is that-the-strands composing the bond terminal -are--more,or;:le ss interfused into a solid molded bond:head which is attached to the rail with a high degree of permanence.

In the modified construction illustrated in Figs. 4 and'5, the crucible 34 is provided with a pouringlip 35 instead of ,with asprue opening, and a handle 36 is attached thereto b means of a clamping ring 31. Th charging cover '38,which is-similar in-form with thatpreviously described,

-i .hinged.to the crucibleon-the side toward-the handle and aspring catch 39 isprovided on the latter to engage and retaintnecover in open positionwhen pouring molten metal from the crucible. ThisfOrm of crucible i particularly adapted for use in the production of .relativelylarge charges. of molten metal producedv b exothermic reaction, themetal then being poured into one or more molds in conventional manner.

The various features .of construction which.

characterize 'my. improved crucible, of which several forms are herein illustrated and "described, forms the subject matter of myico-pending application filed January 13, 1941,. Serial .No. 374,229, out. of which the present:applicationhas been divided.

Other modesofapplyingthe principle of my invention may be employed instead of the one explained, change being made asregards the method herein disclosed, provided the step or steps stated .by any ofjthe .followin claims or-the equivalentpf such stated step or steps be employed. g

,I therefore particularly. point outand distinctly claim as my invention:

1. In a method of charging a crucible..;with material .for producing molten metal .by vexothermic reaction, such material comprising a mixture of. ingredients comminuted .to different degrees of I fineness, the steps which .consist in permitting a measuredbody. ofsuch materialto flow freely by gravity through an openingrestrictedin area relatively. to. thecross section-of such, crucible .and located. approximately centrally over such-crucible, whereby suchjmaterialis deposited in the form of a symmet1 'ical,, 'mounded mass wherein the component ingredients are. distributed uniformly in successive descending planes and then similarly placing on the mounded topof such body a smallerbody .of ignition powder. 1 r

2. In a'method of chargin a crucible with material for producing molten metal by exothermic reaction, such material. comprising amixture of ingredients comminuted to dillerent [degrees .of fineness, the steps whicheonsistin .pouring 'a measured body of; suchmaterial. into such crucible -from, above. .and ;restricting the flow oilsirch body where it enters the-crucible :to. a n areasubrespect to the latter, whereby such material is deposited in the form of a symmetrical, mounded mass wherein the component ingredients are distributed uniformly in successive descending planes.

3. In a. method of charging a crucible with ma terial for producing molten metal by exothermic reaction, such material comprising a mixture of ingredients comminuted to different degrees of fineness, the steps which consist in pouring a measured body of such material into such crucible from above, and restricting the flow of such distributed uniformly in successive descending planes, and then similarly discharging on the mounded top of such body a smaller body of ig- 10 nition powder.

CHARLES A. CIADWELL.

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