US2479641A

US2479641A - Crucible

Info

Publication number: US2479641A
Application number: US596261A
Authority: US
Inventors: John J Ripich
Original assignee: Individual
Current assignee: Individual
Priority date: 1945-05-28
Filing date: 1945-05-28
Publication date: 1949-08-23
Anticipated expiration: 1966-08-23

Description

Aug. 23. 1949. J. J. RlPlCH CRUCIBLE Filed May 28, 1945 2 Sheets-Sheet 2 fia. 6.

/NI/ENTOIP JOHN J. RA /CH /4 rrak/ver.

Patented Aug. 23, 1949 UNITED STATES PATENT I OFFICE 4 Claims.

This invention relates generally to apparatus for melting, heating, reheating and superheating metals preparatory to pouring into sand molds, permanent molds, die cavities or the like for the purpose of producing castings.

More particularly, this invention relates to crucibles, pots, ladies, or similar vessels which are used for melting, heating' and/or pouring liquid metals into molds and which are formed of high heat and distortion resisting metals or of non-metallic refractory materials, depending upon the conditions under which the crucibles are used and upon the temperatures incurred.

In the melting of the metals, impurities which have a deleterious effect on the castings, frequently collect or develop in the molten metal, which impurities accumulate either from the original metals placed in the crucible or originate from contact of the molten metal with the material of which the crucible is made, or develop from Chemical reactions occurring during the melting or heating processes. In some cases these impurities :collect at the top of the molten metal in the form of slag, which may readily be skimmed off just prior to pouring of the metal into the mold. In other cases, however, particularly in the melting of lighter metals, such as magnesium, for instance, certain deleterious impurities collect at or gravitate toward the bottom of the bath of molten metal. In the case of these light metals, these impurities, if poured into the mold cavities, result in unsatisfactory and/or defective castings. Inasmuch as most of the light metal castings are used in airplane Construction, the elimination of the impurities producing such defective castings is manifestly of vital importance Due to the fact that it is desirable to avoid the agitation of molten metal subsequent to its final heat treatment, and the subsequent re-mixing of the impurities with the pure metal, it is desirable that the metal be poured from the vessel in which the final heating operation is eifected and this invention, in its preferred form, is accordingly embodied in a vessel which is adapted to serve both the functions of a heating crucible and a pouring ladle. i

This invention has acccrdingly for its principal object the production of a combined crucible and pouring vessel which' is adapted to melt and/or heat treat the metal and to prevent the passing into the mold, of impurities accumulated in the lower portion of the liquid metal during the pouring operation.

A further object of this invention is to produce such a crucible and pouring vessel which is 55 adapted to prevent, during the pouring operation, the re-mixing of the impurities in the lower portion of the molten bath with the pure metal in the upper -portion of the bath and which is adapted tohold back and prevent the contaminated portion of the metal bath from passing into the mold.

A further object of this invention is to produce a crucible with a hold back provision of the above type, in which all interior surfaces are readily cleanable to avoid contamination of succeeding heats of molten metal with impurities accumulated or developed in a preceding heat.

It is a further object of this invention to develop a vessel of the above character which is formed with a wall having a substantially uniform thickness, to the end that a uniform heat transference may be effected thru the wall thereof, thereby to transmit the heat uniformly to all portions of the metal bath and to prevent the development of unequal heating and cooling strains in the wall of the crucible when it is subjected to the heat of the furnace.

Another object of the invention is to provide an improved vessel having means associated therewith which cooperate with the top of the furnace for suspending the main body of the vessel within the furnace chamber and which maintains the upper portion of the vessel above the top of the furnace where it is not subjected to the intense heat of the furnace and thus retains sufiicient strength to maintain the vessel in its original shape. t

It is also a further object of this invention to produce a pourng vessel fulfilling the above objects which can likewise readily .be used for melting, heating, re-heating or super-heating metal in heating furnaces of the type usually found in foundries and which vessel can be handled with the present type of conveying and handling equipment used in foundries.

Further and more specific objects of this invention will become apparent from the following description and claims.

Referring to the drawings:

Fig. 1 is an elevation illustrating a crucible embodying this invention, shown in association with a portion of a heating furnace, the furnace being shown fragmentarily in section and the crucible being shown in front elevation, that is, viewed in a direction looking toward the spout or pouring side of' the crucible.

Fig. 2 isa side elevation of the crucible shown in Fig. 1, detached from the furnace structure.

Fig. 3 is a plan view of the crucible shown in Figures 1 and 2.

Fig. 4 is a vertical axial section of the crucible, this View being taken on an axial Vertical plane passing thru the pouring spout of the crucible, the crucible being shown partly filled with molten metal and a ring of a lifting and manipulating frarne adapted for manual pouring being shown supporting the crucible.

Fig. 5 is a view showing the crucible illustrated in Fig. 4 tilted in a counterclockwise direction to a position in which most of the molten metal has been discharged from the spout.

Fig. 6 illustrates in plan View, a crucible lifting and manipulating device of well known type,

used for manually pouring molten metal from the T crucible.

Fig. '7 is a plan section taken on the plane indicated by line 1, l, of Fig. 4.

The drawings illustrate this invention embodied in a crucible formed of a high beat and distortion resisting low alloy steel, which is used for the purpose of melting, heating and pouring magnesiurn, magnesium alloys and similar metals.

The crucible illustrated consists of a body indicated in its entirety at l and comprises, in the embodiment disclosed, a generally com'cal side wall 2 of uniform thickness diverging upwardly and outwardly and a base portion 3 flared upwardly at its periphery With a relatively large radius of curvature and' terminating in an upwardly extending flange 4. The side wall is formed into a conical shape by any suitable means such as bending rolls from a rolled plate of metal of the desired thickness and is welded along one or more longitudinal seams. p

The base portion is also formed from a rolled metal plate and is formed by a dishing or forming operation, preferably with the aid' if dies. The base portion 3 is secured to the side wall desirably by welding the upper edges of the flange 4 to the lower portion of the side wall 2, as shown at 5. At the upper edge of its front portion, the side wall 2 is deflected outwardly to form a pouring spout or discharge lip 6. The base portion of the crucible is preferabl-y, tho not necessarily, formed of slightly thicker metal than the metal of the side walls in order to more effectively resist the deteriorating attack on the metal of the crucible by the flames in the urnace, during heating of the crucible, whichdeterioration is more severe at the base of the crucible.

An alloy which has been found to be exceedingly durable and highly resistant to distortion,

checking and corrosion, in crucibles of the type herein described, when used for melting, heating and -superheating magnesium and magnesium alloys, is fully described and claimed in my copending application entitled Heat resistant low alloy steel, filed December 21, 1945, and bea-ring 'Serial No. 636A97, and now issued as United States Patent No. 2,4671701,

This crucible is provided with a pair of brackets or lugs l', disposed on opposite sides of the crucible, each formed at its lower Vend with a foot or flange 8 and ormed adjacent 'its upper end with an opening 3 adapted to receive a crane hook, hoisting bar or other lifting accessory. The fianges 8 of the brackets l are located a substantial distance below, and the openings 9 are located above the upper edge or rim of 'the side wall 2.

As will appear from Fg. 1, the flanges 8 of the lugs 'l are adapted to rest on the :upper :face of a cover plate n forming the top of a 'furnace li.,

having side walls |2, !2. As will be understood, the furnace is provided with any convenient means for heating, such as fue] oil or gas, which heating means need not be here further referred to, as it forms no part of this invention.

For purposes of convenience in further description, reference will be made to a fore and aft plane passing thru the vertical axis of the crucible and thru the pouring spout, this plane being indicated 'by line X, X in Fig, 3.' Reference will also be made to a transverse plane passing thru the vertical axis of the crucible and thru the

brackets

1, 1, this transverse plane being indicated by the line Y, Y in Fig. 3.

' At a point in the front portion of the side wall 'below the pouring spout 6, the metal of the side wall is deflected or indented inwardly as shown at !3 forming a generally horizontal depression !4 simulating a groove, in the outer surface of the side wall and forming a corresponding protuberance extending inwardly into the otherwise generally conical interior space of the crucible, as shown at l5. a

The indentation or protuberance i is formed with a rounded or convex shaped elongated nose orridge I a extending preferably horizontally in the manner of a chord entirely across the interior space of the crucible from one side of the crucible to the other, this inner edge orrounded nose of the protuberance being substantially par-.allal to the transverse plane Y, Y and perpendicular to the fore and aft plane X, X.

The lower portion of this indentation is ormed by a substantially fiat Wall IT merging with the front portion of the side wall below the indentation with a curve of relatively large radius as shown at 18. The upper portion of the indentation is formedby a relatively flat portion indicated at !9, this portion* 19 being preferably, tho not necessarily, substantially alined with the bottom 'E of the trough forming the pouring spent 6. The indentation !3 is preferably fol-'med with suitably formed dies between which the side wall of the crucible -is placed, as a result of which the metal of the Originally generally conical side wall is re-formed to produce the desired shape of indentation.

It will be apparent that the rounded or convex-shaped elongated nose or ridge 16 and adjacent portions of the indentation 13 form a dam or barrier extending partly across the inner space of the crucible and adapted to confine or hold back metal which would otherwise pass to the pouring spout,

It will also be noted that the indented portion othe ,front wall 13 is formed integrally of the metal of theside wall 2 of the crucible and that all portions of the walls forming the indentation 13 are substantially uniform in thickness with the thickness of the remainder of the side wall ofthe crucible.

In Fig. 6 is illustrated a lifting rame 20 of a well known type used in foundries for the purpose of lifting, conveying, and manipulating smaller sizes of crucibles and ladles containing molten metal. e I

This lifting frame consists of a ring 2! formed with `an interior seat 22 preferably but not necessarily conical in conformation. Fixed to this ring on one side-is a bar '23 terminating in a pair of spaced hand grips 24. Fixed to the opposite side of the ring ZI is a preferably pia-in bar 25. In operation this lifting frame is usually placed on the foundry ,floor and the .crucible or ladle with which the liftng frame is to be used, is lowered onto the 'floor within the ring.` The frame is then lifted by operatives, one at each end, and between them they carry the -crucible or ladle to the mold into which the molten metal is to be poured, one of the operators tilting the ladleduring the pourng by means of the hand grips 24. The ring z' and the seat 22 engages substantially morethan half of the periphery of the adjacent 'side wall ?of the crucib1e,7even tho the vertical position of the ringis substantially level with the indentation l3.

Fig. 4 illustrates the crucible in section on the fore and aft plane X, X and shows the crucible well filled with molten metal, the upper or pure portion of which is indicated at A. certain impurities have accumulated in the molten metal either from the metals Originally deposited in the crucible or from contactof the molten metals with the'wall of the crucible'lor from chemical reactions' arising during the' melting. These.. impurities have contaminated a portion of the metal indicated at B, at and adjac'entthe bottom of the bath of liquid metal. These impurities, when the crucible is used'for' the melting or superheating of magnesium or magnesium alloys iriclude among others, magnesium oxides, magnesium nitrides, magnesium hydroxides, and fiuxes.

As hereinbefore stated, this improved crucible has, as one of its important objects, the prevention of the passing of these impurities into the casting cavity in the mold or die When the metal is poured, thereby avoiding the production of inferior and defective castings. The manner in which this crucible effects this result will readily be clear from an inspection of Fig. 5 in which the crucible is illustrated as having been tilted, by the instrumentality of the lifting frame 23, to a position in which most of the pure metal A, Fig. 4, has been poured ofi the top of the bath and in which the impure or contaminated portion of the metal B has been held back by the barrier IS. The degree to which this crucible may be further titlted to discharge more metal is dependent upon the proportion of impure metal remaining in the crucible. It is to be noted, however, that under no conditions can the crucible shown be completely emptied inadvertently by a careless operative, for the reason that the crucible would fall out of the supporting ring by gravity, long before the contaminated metal in the bottom of the crucible could flow over the barrier IE. The contaminated metal B or any residue remaining in the crucible can readily be poured out of the back of the crucible by tilting the crucible in a clockwise direction suificiently to permit the resdue to flow out or be cleaned out, which can safely be done without any danger of dropping the crucible.

It will be evident that the inclination of the flat wall l' below the barrier !6 and the smooth inner surface of the crucible and absence of sharp corners or recesses makes the entire interior surface visible and readily accessible for cleaning.

The location of the barrier forming nose !5 radially inwardly from the side Wall and its location vertically above the bottom depend on the proportion of the total contents of the crucible which it is desired to hold back. The radially inward position of the transverse nose l 6 is preferably short of the half way point across the crucible in order that the visibility for inspection and accessibility for cleaning may not be interfered with and also in order that, in crucibles of the sizes to be manipulated by the lifting frame, a seat in excess of one half of the circle may be afforded 6.* for the engagement with th ring of the lifting frame. i j

It is also to be noted that the rim at the top of the side wall of the crucible projects above the Iurnace and is not exposed to intense heat and is therefor not softened during the heating of the crucible. This rim accordingly maintains its original shape and helps to keep the entire upper portion of the'sde wall'of the crucible in its original shape.

It isalso noted that .this invention is not limited to crucibles of a size which may manually be transported and poured, as this 'invention may be embodied with equal advantage in the larger sizes adapted to be 'transported and tilted for p-ourng by suitable hoisting and crane equipment. I i i Many modifications of this invention will naturally occur to those skilled in this 'art andthe present disclosire should therefore be oonsidered as typical only and applicant desires not to be limited to the exact' Construction shown and described. i

What I claim is: e i

1. `A vessel for melting metal and superheating molten metal of the type in which impurities in the molten metal gravitate 'toward the bottom of thevessel, said vessel including a pouring spout in its upper portion and having below said spout an inwardly projectin protuberance comprising two substantially fiat surfaces intersectiug to provide a generally downwardly facing shoulder having an inner edge which extends a substantial distance within the vessel and forms r a substantially straight chord across the periphery of the vessel at the point of intersection with the periphery, the protuberance extending within the vessel a sufficient distance to cause said shoulder to a-ct as a barrier for retaining below said protuberance the part of the metal containing the major portion of the impurities while comparatively pure metal is being poured from said vessel through said spout.

2. A vessel providing a chamber for a charge of molten metal containing impurities which gravitate toward the bottom of the charge and are desirably retained in the chamber while relatively pure metal is poured from the chamber by tilting the vessel, said vessel having a bottom wall and a side wall upstanding therefrom and terminating in an upper rim, a portion of the rim extending outwardly to form a pouring spout, a portion of the inner surface of said side wall between the pouring spout and the bottom wall extending inwardly into the chamber substantially beyond portions of said inner surface below said inwardly extending portion and formed with a substantially horizontally disposed straight inner edge forming a chord of the periphery of the vessel at the point of intersection and providing a generally downwardly facing shoulder in the chamber simulating a segment across the chamber and adapted to act as a barrier for retaining in the chamber below the inner edge the bottom of the charge when the vessel is tilted, whereby relatively pure metal is poured over the spout.

3. A vessel providing a chamber for melting and superheating a charge of molten metal containing impurities which gravitate toward the bottom of the charge and are desirably retained in the chamber while relatively pure metal is poured from the top of the chamber by tilting the vessel, said vessel having a bottom wall and a side wall integrally connected with the periphery of the bottom Wall and terminating at its upper edge in 9. `rim, 'a portion 'of th rim being deflected outwardly to form a pouring lip 'and a portion of the side wall below :the "lip 'being indented inwardly within the 'contour 'of 'the adjacent portion of the side wall, `said 'inwardly indented portion 'extending a substant'iai distance within the chamber and :forming at its inner edge a substantially straight chord across the contour 'of the -chamber *at its interseo'tion with the side wall and providing an inwardly extending barrier for retaining in the chambe'r, 'when the vessei -is tilted toward the ;pouring 1ip,-the part of the #metal containing the major portion o said impurities, ,said inwardlyindented portion of the side wall being integral 'with and of substantiany uniform' thickness with the adjacent side wall.

4. A vessel for melting metal and superheat'ng molten metal of a type "in which 'impurities in 'the molten metal gravitate toward the bottom of the vessel, said vessei having a c'iroular bottom and a side wall 'of substantiany truncated con ical shape and being distorted 'from such :shane by being defiected outwardly in an upper portion to provide a pouring spout and by being defiected inwardly below said spout ,in two substantia'lly flat wa11e`d portion's forning a dihedralangle and extending a substantialdistance within the ves- 8\ se! and' interseoting in a 'subs'tantially 'straight fine, said inte'section forming :a chord of the e'ircumference 'of the vessel at 'the line of intersection and providing :an jinwardiy extending protuberance having a generaliy downwardly facing shoulder overlying 'a segmental portion of the 'bottom of the ve'ssel to form "a 'barrier for retai-ning a part of the metal containing the major portion of the 'impuri'ties while the comparativeiy pure metal is being poured "from said vessei through 'sa-id spou't.

5 JOHN J. RIPICH.

REFERENCES CITED 'The following references are of record in 'the file of this patent:

STATES PA'I'ENTS Number Name Date 612,'134 Levoz Oct. 11, 1898 ?14,804 Laird Dec. 2, 1902 '862,008 .Nobel July 30, 1907 992599 Ross May 16., 1911 1,573,'5'35 Bellis Feb. 16., 1926 15333576 Swigert June 28, 1927 2,173,`063 Harris Sept. 1'2, 1939 2324514 Jung Dec. 10., 1940