US2798268A - Mold plug - Google Patents

Description

July 9, 1957 D. D. WHITACRE 2,798,268

MOLD PL G Filed on. 28. 1955 IN VEN TOR.

A TTOE/VEYS United States Patent MOLD PLUG Donald D. Whitacre, Waynesburg, ()hio ApplicationOctober 28, 1953, Serial No. 388,777 7 Claims. (Cl. 22-148) This invention relates to the art of casting steel ingots and more particularly to ingot mold plugs, and their relation to the mold and ingot in respect to closing the bottom opening of the mold in the first instance and providing, or facilitating the provision of, a stool or support for the ingot after the ingot has been cast and taken from the-mold and, for example, placed in the soaking pit..

In theart to which my invention pertains the desirability of obtaining a secure attachment between a refractory'mold plug and the ingot cast thereabove in a bigend-up mold has long been recognized. To the extent that this result has been attained in greater or less degree it has been accompanied with burdens as to cost on the one hand and with an undesirable uncertainty of performance on the other hand.

This phase of the problem to which my invention is addressed has been to provide a plug so capable of attachment to the ingot that substantially 100% of all the plugs employed in service will be withdrawn in their whole and complete entirety with the ingots and serve as stools for the ingots in the soaking pit. 'Withal it is desirable that the plugs be economical to make and use and perform theirother functions efficiently.

In this aspect my invention may be regarded as an improvement upon the type of plug shown in the Estep Patent No. 2,113,445 in which the bondbetween the ingot and the plug was achieved through a steel plate preliminarilyattached 'to' the upper surface of the plug but, necessarily, with the attendant cost of providing and securing the plate to the plug in the first instance.

The laterRamsey Patent No. 2,234,634 and Messler Patent No. 2,444,140 suggest other approaches to securing the plugs to the ingots cast above and upon them, but plugs following the teachings of these patents have, in my experience, been disappointingly lacking in uniformity of successful operations and results. My observation has been that ingots frequently fail to attach themselves to such plugs satisfactorily, that the plugs often become fractured and in part lost from the ingots and fail to provide an adequate stool for the ingot in the pit. Additionally the Messler plug tends to fracture horizontally when the ingot is withdrawn, leaving the lower part of the plug in the mold and tainly associated'with the ingot. The Ramsey plug, if tightly secured in the lower tapered mold hole tends to yield up its central core with the ingot while its body and periphery remain in the mold. Forming the Ramsey plug is not without costly difiiculty incident to tapering the outside of the plug one way and tapering or otherwise enlarging the central void the other way.

It is therefore among the objects of my invention to solve the problems and avoid the shortcomings of the prior art practices. Particularly it is among the objects of my invention to provide a strong, economical and efficient mold plug which will stand hard usage as a plug for sealing the bottom of the mold and will inaddition leaving only fragments uncer-' g I 2 uniformly and positively become firmly and entirely attached to the ingot poured and cast above and upon it and will in substantially every instance be removed therewith when the ingot is stripped from the mold. Additionally it is among my objects to provide a plug so {voided for reception of molten steel from the ingot that the form and strength of the extension of the ingot cast in the plug will strengthen the plug as a stool and will of itself tend to serve as a useful stool for the ingot should the plug be fractured or wholly or partially detached from the ingot at any time before its intended usefulness had been completed.

A further object of my invention is to provide a burned clay ingot mold plug having slots formed therein to receive molten metal during pouring and to effectuate a secure bond between the plug and the solidified ingot; the said slots having such novel characteristics as to substantially reduce the stress between bonding points and the probability of the plug fracturing in either a horizontal or vertical plane during the pouring and/ or solidification of the ingot and the stripping of the mold.

A further object of my invention is to provide a burned clay ingot mold plug which will have improved drying and burning characteristics, whereby the drying and buming time for making the plugs will be substantially reduced and the plug more uniformly burned and hardened throughout.

These and other objects and advantages of my invention will appear more fully and particularly from the following description and the appended drawings of a preferred form of my invention in which:

Figure 1 is a top plan view of an enlarged scale of an ingot mold plug formed according to the preferred form of my invention;

Figure 2 is a sectional view taken on the line 2-2 of Figure 1;

Figure 3 is a sectional view on a scale smaller than Figs. 1 and 2, with parts broken away of a forming and molding apparatus suitable for forming ingot mold plugs according to the method of my invention;

Figure 4 is a bottom plan view, on the scale of Fig. 3,

of the forming ram or plunger of the apparatus of Fig. 3;

Figure 5 is a fragmentary longitudinal vertical section on a further reduced scale showing the lower part of an ingot mold with an ingot cast therein and engaging the mold plug, the latter being partly broken away from the finned extensions of the ingot cast therein;

Figure 6 is a top plan view on the scale of Figs. 3 and- 4 of a modified form of mold plug according to my invention employing transversely curved slots, and

Figure 7 is a top plan view on the scale of Figs. 3, 4 and 6 of another modified form of mold plug following my invention with the ingot fin receiving slots transversely splined or staggered.

A burned clay ingot mold plug P, Figs. 1 and 2, embodying the preferred form of my invention is of truncated frusto-conical shape, circular in cross-section and has substantially parallel upper and lower surfaces, 21 and 23'respectively.

I prefer that ingot mold plugs embodying my invention be formed by extruding wet clay stock, so as to form extruded right circular cylindrical slugs S, Fig. 3, which are forcibly pressed into truncated frusto-conical external form and given a slotted internal configuration receptive and determinative of integral fins F to be cast therein with the ingot, Fig. 5.

To carry out the objects of my invention the plug P serves both to plug and close the conventional tapered bottom opening of an ingot mold M, Fig. 5, and the plug also serves as a mold for the integrally finned extensions F of the ingot I which are cast in the voids or slots 25 of the plug when the ingot is cast in the mold M. Thus 3 theslots 25 in'theplug Ptake the female form of which thefins F- havethe male form.- Similarly the finnedextension 13 of the ramming plunger 11, Fig. 3, which works I having enlarged cylindrical terminal ends 31 struck on the slug S to form, inter alia, the voids 25 in the plug P, A

tion,-- Figs.- 1- and 2, the voidsj o'r slots QS eXtend at rigPQ angles to -.ea ch otherarid extend perpendieiilar to theltop is a substantial replica- (re'gard; being' hadi-foif- 5 finned'exte 1 and bottom; surfaces of the plug if e. p'ai'allel'to the axis of the cone of-the ex terior'surface of the p lug, andextend from the top surface 21,- of- -the plug, where they are ,open, 7 nearlytothe bottom of the-plug where they :are closed. Theslots 25'1316' long-andnarrow, i. e; wide and; thin, v transversely of the plug-as'viewedin-Fig.1 andfare deep and narrow longitudinally of the plug as viewed in vFig. 2. For uniformity 'I' shall call the greater transverse dimensions as-vieWedinFig. l, the-wid thgof the slots; the'lesser dimension the thickness, and thelongitl ldinal dimension,

Fig: 2, the length or depththereof.

In this sense I prefer that the-width of 'the slots .be about'or somewhat greater than half the maximum diameter; of the upper and-greater face of the plug so that the-fins'Fwill engage the plug widely and deeply and in its substantial entirety to avoid the unfortunate tendency of prior practices in which limited extensions. of the ingot cast into the plug tended to engage. and remove from the mold opening only fractional parts of the plugs. V

Ingot mold plugs embodying my invention maybe formed, for example, inthe upsetting apparatus shown in Figure 3, The apparatus includes a forming'mold' M which has a molding cavity C. The cavity C comprises. an upper cylindrical bore 3 and a lower cylindrical bore 5 of smaller diameter with a conically taperedwallportion 7 therebetween whichforms theupsettingor molding chamber andcorresponds substantially. to the external shape of the finished plug. An ejector piston or plunger. 9, which is slidably disposed within the bore 5, functions as the lower end of the chamber 7 during the upsetting operation. A ram 11 is slidably disposed within thebore 3 and hasforcible-downward movement. The lower face of the ram 11- is smooth and normalto the vertical axis of the cavity C. Extending downwardly from the lower face of the ram 11, and securely attached thereto,'is the finned extension 13 which has the male form of. the slots 25;

In use a wet plastic slug S having a volume substantially equal to the volume of the finished plug is placed inthe cavity C in approximately the position shown in Figure 3 and piston 9 is positioned to close the bottom of chamber 7. The ram 11 is then given forcible downward motion, forcing the fins 13 into the slug and the slug into the chamber 7. When the ram 11 has completed its stroke, the fins 13 are entirely within the slug which lies entirely; withinthe chamber 7. The slug has the form. of a, finished plug (Figures 1 and 2) except for any shrinkagev which may occur in burning. The ram 11 is thenwithdrawn and concurrently or in timed sequence thepiston 9 is forced upwardly raising the wet plug to a position from which it may be manually removed conveniently. The plug is then dried and burned in the usual manner.

It is among the advantages of my invention that'the extensively voided interior of the plug materially enhances both drying and burning of the finished product giving it better qualities of finish, strength and hardness witli= lesser drying and burning times than have been. required for mold plugs of the prior art forms and structures.

abouta A" radius r and symmetrically disposedin relation to the intervening straight rectangular parts of the slots. In this form I prefer that the slots have a depth d of 3" to 3 /2".

In this form of my invention when the plug is tightly placed in the lower tapered opening of the ingot mold M,

Fig. 5, and the molten metal poured therein the metal enters the slots and openings in the plug and takes the obverse form thereof in the form of the structure of the fins F integral with; the ingot which is poured and cast thereabove. The hot metal entering and filling the slots strikes into the surfaces and/ or porosity, if any, thereof and probably tends to effect a surface bond therewith. I believe it is likely that the metal tends to fuse the clay at the exposed inner surfaces of the slots while the specific heat of the clay mass of the plug chills the metal of the fins. Concurrently the whole plug receives heat and; tends to swell and expand from contact with the ing'ot; and the fins and from the. mold as the sameis heated by the molten metal. I. am not presently minutely aware of all the details of heat flow and. transfer by. and

between the metal, mold and'plug, but I have observed that'when the ingot is removed from the mold the plug has become securely attached'and/ or attached and bonded;

cools and shrinks, to be drawn toward each other and thereby gain a grip on the plug not unlike the grip. of thethumb and fingers of the human hand in a bowling ball. As presently advised I also believe it to be a tenable, if partly or apparently inconsistent, theory of the mode of operation of my invention that the metal of the fin structure F chills to a relatively incompressible state, while the plug is still in a state of heated expansion from which state the plug as it cools contracts upon and squeezes and grips the fin structure. I also believe that both operations may take place with the end enlargements exerting radial inward gripping force on the plug and the plug contracting upon theelongated radial parts of the fins and possibly augmenting the grip directly and in 'chordal, reaction against the inward radial force of the terminal enlargements. With either or both. the above theories and/or with my belief that a strong surface bond is established between the fins and the slots the results obtained by the use of my plugs have materially and substantially promoted the art and enhanced the economy and facility of casting ingots.

The modified form of my invention shown in Figure 6,

differs from the preferred form only in the specific con- .figuration'of' the slots 35 in the plug P as compared with the slots 25 of the plug P. The slots 35 may correspond to the slots 35 in all ways and essential dimensions except, as shown, that the slots 35 lack terminal enlargements and are curved between the central point of intersection and the extremities thereof. The plugs P may bemade in the same way as the plugs P; the extension of the ram 11 corresponding to the slots 35in the same way as the extension 13 corresponds to the slots 25. In the form of Figure 6 the plug will be bonded and attached to theingot with substantially the same surfacebond and the net grip and contraction of and between the plug and fins willbe governed by similar forces and influences and achieves similar desirable results.

In the modified form of my invention illustrated in Fig. 7 the plug P differs from the plugs Pand P in all respects only in the transverse configuration of-the slots 45 compared with the'slots '25 and 35 discussed above. The slots 45 are preferably similarly disposed and proportioned; extend; bodily-radially outwardly from the axis of the plug but preferably have their verticalfaces grooved or fluted as at 46 whereby to enlarge the surface bonding area and to facilitate radial grip between the fins cast therein and the plug regardless of which does the final radial contraction upon the other.

In all forms of my invention the fin structure cast in the plug preferably takes the form of an X or cross column having great strength in longitudinal compression whether or not the fin structure acts with and within the plug so that they both share the load of the ingot when they serve as a stool for the ingot, or the fin structure is called upon to serve alone as the stool in the event the plug should be lost ,or damaged. Additionally as the practice of increasing the size and weight of ingots progresses my invention provides greatly augmented strength in and with the plug, or without all or part of the plug, for supporting the ingot as a stool, and permits the use of small or lighter and/or relatively weaker plugs per so. It will be appreciated that the column strength of the fin structure F may, if desired, be increased by appropriate increase of the thickness of the sections, for example, without impairing the other objects, purposes and results of my invention.

In all forms of my invention the whole surface area of the fin structure F which has bonding contact with the complementary surfaces of the slot configuration in the plug is with the advantages mentioned far greater than any prior practice. In the exemplary form of my plug above described this surface area is about twice the diametric trapezoidal cross-sectional area of the plug.

While I have illustrated and described preferred and modified forms of my invention, changes, other modifications and improvements will occur to those skilled in the art who come to understand the principles and operation thereof, and therefore I do not intend or desire to be limited in the scope of my patent to the forms of my invention herein specifically illustrated and described nor in any manner inconsistent with the progress of the art which my invention has promoted.

I claim:

1. An ingot mold plug having a central axis, an imperforate bottom wall and internal slots opening through the upper surface thereof, said slots extending nearly to the bottom of the plug and extending outwardly from said axis approximately half the radius of the plug and having a width many times their thickness and having a gross surface area exceeding the diametric cross-sectional area of the plug.

2. The ingot mold plug of claim 1 in which at least one of said slots has a portion offset from radial alignment with an adjacent portion.

3. The ingot mold plug of claim 2 in which said slots have enlarged portions at the ends thereof remote from said axis.

4. The ingot mold plug of claim 2 in which said slots are curved.

5. The ingot mold plug of claim 2 in which said slots are fluted.

6. A burned clay ingot mold plug of frusto-conical exterior form with an imperforate bottom wall and internal wide, deep and narrow slots opening through the top surface of the plug and adapted to receive molten metal when the ingot is poured and form a fin structure in the plug integral with the ingot and facilitate attachment between the plug and the ingot when the ingot is removed from the mold, said slots being angularly related to each other and extending cross-wise from the vertical axis of the plug and intersecting substantially in said axis and lying perpendicular to said top surface and having a Width diametrically of said plug many times their thickness and not substantially less than half the mean diameter thereof and having a depth approximating the depth of the plug and having a gross surface area approximately twice the diametric cross-sectional area of said plug.

7. The mold plug of claim 6 in which portions of said slots spaced from said axis are ofiset from other portions transversely of radial planes passing through said axis.

References Cited in the file of this patent UNITED STATES PATENTS 332,656 Hinsdale Dec. 15, 1885 2,234,634 Ramsey et al. Mar. 11, 1941 2,444,140 Messler June 29, 1948 2,572,754 Patterson Oct. 23, 1948

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