US2170555A - Ingot mold plug - Google Patents

Description

Aug. 22, 1939. A. c. ESTEP INGOT MOLD PLUG Original Filed Sept. 3, 1937 Enventor attorneys Patented Aug. 22, 1939 INGOT MOLD PLUG Arthur C. Estep, Waynesburg, Ohio, assignor to The Whitacre-Greer Fireproofing Company, Waynesburg, Ohio, a corporation of Ohio Application September 3, 1937, Serial No. 162,315

. Renewed May 25, 1939 Claims. 01. 22-148) ingot mold; that is, a mold having an open top with side walls gradually diverging from the bottom toward the top. A tapered hole is provided at the bottom of the mold which is closedby a sealing plug while the ingot is poured and the ingot, after cooling, is forced upwardly out of the mold. Prior to pouring the ingot the plug referred to is forced into the hole at the bottom of the mold which hole is tapered according to the accepted practice so that the plug may be driven into the hole and have a snug fit which prevents the escape of molten metal during the pouring of the ingot. Because of its ability to accommodate itself to the contour of the hole at the base of the ingot mold as by limited surface crushing or abrasion against the wall of the hole, an ingot mold plug formed of burned clay is capable of effecting an efficient seal. The present invention relates principally to an improved refractory ingot mold plug, and the method for making same.

It is among the objects of my invention to provide a burned clay ingot mold plug and method of .making the same whereby the plug will an withstand the shock to which it may be subjected while being driven into the tapered hole of the ingot mold and will withstand the thermal and physical shock occasioned by the flow of molten metal into the mold. Another object is to provide a refractory plug which will not spawl in the area of contact with molten steel or otherwise give off non-metallics to the ingot. It is a further object of my invention to provide a method of making an ingot mold plug which will 4 give in the finished plug certain structural characteristics of yielding strength whereby to resist deleterious fracture or spawling in use. It is also an object of my invention to provide an ingot mold plug with circular concentric laminations which will tend to restrict any fracture of the plug to the direction defined by the laminations. It is a further object of my invention to provide a method of making an ingot mold plug in which an extruded clay tile cylinder is upset to form a plug having a truncated cone shape. It is a further object of my invention to provide an apparatus for carrying out the method for making the article in accordance with the preceding objects. It is a further object of my in- 55 vention to provide an apparatus for upsetting a ceding object.

cylindrical clay slug into a truncated conein which means are provided to compensate for variations in slug volume. It is a further object of my invention to provide a burned clay mold plug characterized by smooth troweled outer sur- I faces especially resistant to spawling and cracking.- It is also among the objects of my invention to provide a method and apparatus for making a mold plug in accordance with the pre- Further objects and advantages relating to economies of manufacture and characteristics of the finished mold plug will appear from the following description and the appended drawing in which:

Figure 1 is a view of a clay extrusion apparatus suited to extrude laminated cylindrical stock employed in my invention;

Figure 2 is a sectional view with parts broken away of an upsetting or molding apparatus made according to my invention; 20

Figure 3 is an enlarged sectional view of the relief mechanism employed in the upsetting or molding apparatus;

Figure 4 is a transverse sectional view (taken along the line 4-4 of Figure 5) of a mold plug constructed according to my invention;

Figure 5 is a plan view of the mold plug;

Figure 6 is a partial sectional showing of a mold plug according to my invention arranged within an ingot mold.

The first step in forming a mold plug corresponding generally to the objects outlined above comprises extruding wet clay stock of round cross section such as l in Figure 1. Preferably the clay stock is extruded from an auger machine 5 of the type in which the mass of wet clay being extruded is open to the atmosphere through a hopper as at 8 to facilitate the formation of laminations in the extruded stock 4. There is a tendency for extruded clay products to form laminations generally parallel to the walls of the extrusion die and in forming certain articles it is conventional practice to extrude from a chamber maintained at less than atmospheric pressure to prevent the formation of laminations. According to my invention, however, I prefer to take advantage of the laminating tendency referred to and therefore prefer that there be little or no deaerating of the extruded mass. In addition to insuring against deaerating the mix should 60 be sufficiently short so that marked circular concentric laminations coaxial of the stock will be formed in portion 4. The clay may be fed to the auger machine 5 from a pug mill 1 in the usual manner and forced by an auger through the extruded stock 4 is severed by wire cutters or other suitable means into short cylindrical slugs 6 having a volume corresponding substantially to the volume of a finished mold plug.

Subsequent to the extrusion of the clay sto 4 and thecutting thereof to provide cylindrical slugs 6, the slugs are each transferred while in a plastic condition to an upsetting apparatus arranged to upset the cylindrical slug into a plug having a truncated cone shape. In Figure 2 I have illustrated a preferred form of upsetting apparatus in which a pair of cylindrical bores l9 and 26 are joined to each other by a tapered wall portion 2| which corresponds sulntantially to the shape of the finished mold plug. A backup or ejector plunger 24 is positioned within the bore IS to close the lower end of the upsetting chamber and the upsetting plunger 26 is arranged within the bore 20 so that it may be moved to close the opposite side of the mold plug chamber. I have shown in the dotted lines of Figure 2 a cylindrical mold plug blank 6 as positioned prior to its upsetting and the upset mold plug 30 resulting from the movement of the plunger 26 to its position shown fills the mold plug chamber.

-- resistant covering resulting from upsetting the slug .as above described may be further'improved by effecting a troweling action upon the outer surface of the slug during and/or after the upsetting. The troweling or wiping of the outer surface is preferably accomplished by rotating the plunger 26 and such rotation ispreferably effected so as to affect no disturbance of the lami-' nated structure within the body of the plug. The rotation of the plunger 26 may be accomplished by having the plunger shaft splined axially as at 43 so that the shaft may reciprocate within an internally splined worm gear 4| supported by a bracket 40. A spur gear 42 is arranged to mesh with and drive the worm gear 4|. The rotation of the plunger 26 during and/or after the upsetting of the slug appears to efiect a troweling of the surface which forces water and minute clay particles to the outer surface of the plug, Upon burning the smooth-troweled outer surface of the plug acquires a hard, tough, skinlike cover which is resistant to spawling and thus contributes to the prevention of non-metallics being carried up into the ingot during the pouring thereof.

Due to the fact that as a practical matter in commercial production it is difilcult or impossible to obtain a series of cylindrical slugs 6 which are of exactly the same volume and due to the fact that such plastic slugs are more or less incompressible, it would, in the absence of an apparatus such as I have provided, be difllcult to obtain mold plugs completely shaped and filled. Because of the variation in volume of the cylindrical slugs and because it is desired to produce truncated cone shaped mold plugs of uniform height and full body, I have provided an upsetting apparatus which will compensate for the normal variations in the volume of the cylindrical slugs.

Preferably the back-up or ejector plunger 24 is centrally apertured as at 26 (Figure 3) and carries in said aperture a piercing tool 21 which is normally urged upwardly to the limit of a slot space between the two plungers 24 and 26. When the plastic slug 6 is forced downwardly into the upsetting chamber defined by the two .plungers and the tapered wall 2|, it will be observed that the piercing tool 21 is forced into the plastic mass and that the plastic slug offers a resistance to the movement of the plunger 26 until it has reached the end. ofthe cylindrical bore 20 as shown. As the plunger 26 approaches the position shown it will be understood that the hydrostatic pressure in the slug being upset will force the piercing tool 21 downwardly out of the upsetting chamber against the resistance of the spring 29. The distance which the piercing tool is forced downwardly out of the upsetting chamber by the hydrostatic pressure in the plastic slug will depend upon the difference in volume between the cylindrical slug and the volume-defined by the. tapered wall 2| and the plungers 24 and. 26 in their positions shown in Figure 2. It is possible according to the known methods of cutting plastic clay stock to cut cylindrical slugs in which the volumes will not vary with respect to each other more than the volume of the piercing tool 21 in its raised position. Thus it is possible with the usual known methods of wire cutting wet clay stock and the method and apparatus I have provided for upsetting such stock to obtain mold plugs having a truncated cone shape and having a uniform height and otherwise being uniform in their external dimensions.

The steps which include the cutting and updistinguishable fromeach other by laminations such as l6 shown in Figure 4. Subsequent to the upsetting as described in connection with Figures 2 and 3 the plastic mold plug is burned in the conventional manner and the resulting laminated upset and burned plug 32 is shown in Figures 4 and 5.

The finished plug may be inserted through the open end of an ingot mold 36 and driven into the base of the ingot mold to close the opening 36 therein as shown in Figure 6.- Ordinarily an ingot mold plug of this type is forcibly wedged into the opening 36 by driving and jarring operations effected with a heavy timber or the like reciprocated from the open end of the ingot mold. The impact at the upper surface of the plug may be 'suflicient to effect a,s1ight abrasion or surface fracture of the conical walls of the ceramic mold plug so that the plug will acquire substantially the shape of the aperture 26 to which it is fitted and form a tight seal against the molten metal poured into the mold.

It will be observed that even though the impact of a heavy timber such as is required to force the plug into the mold opening 26 be such as would break or fracture the plug, the truncated laminations defined by surfaces l6 tend to permit the plug sections between said surface to slip with respect to each other. It is possible is fractured two or three times on different concentric conical surfaces' 16 and yet its utility as a mold plug will be preserved. It will also be understood that such plug fracture caused by internal stresses within the plug growing out of the burning and shrinkage will be more or less confined to the surfaces I6 and that regardless of the cause of plug fracture the usefulness of the plu is not destroyed as long as the fracture is restricted to concentric surfaces such as l6.

Among the desirable characteristics of a burned clay mold plug is the resistance of the plug to spawling at the surface due to the thermal shock caused by the inflowingmolten metal as the mold is being poured. A resistance to sp awling or surface fracture is desired in that there is a tendency for the molten metal to float broken or spawled particles of the plug and carry the same up into the ingot. An ingot carrying particles of nonmetallic is obviously defective for rolling purposes. It will be observed that due to the laminations or curved fracture surfaces such as Hi the thermal expansion caused by the sudden inflow of molten metal is broken up or limited by its action by the fracture surfaces "5. The surfaces l6 appear to prevent a heat flow across the upper surface of the plug such as would be suflicient to break away the top layer of the plug from the body of the plug, While it is difficult to determine all of the reasons why a mold plug having concentric laminations is. especially resistant to spawling or surface fracture during the pouring of the ingot I have found that mold plugs having such laminations do resist surface spawling to a marked degree.

Although I have illustrated and described certain specific forms in which my invention may be practiced, various changes and modifications will occur to those skilled in the art, all within the precepts of my invention, and I do not care to be limited to the precise embodiments herein particularly described or in any manner other than by the claims appended hereto when construed with the range of equivalents to which I may be entitled in view of the prior art.

.I claim:

1. A mold plug having a truncated cone shape and a plurality of concentric laminations extending axially of the mold plug.

2. A burned clay mold plug having concentric circular laminations providing concentric fracture surfaces whereby upon mold plug fracture along such surfaces one portion of the mold plug may slip telescopically along said fracture surfaces.

3. A burned clay mold plug resistant to surface fracture due to thermal shock comprising a plurality of concentric portions telescopically nested one within the other with the edges of said portions terminating on the upper face of the plug normally subjected to thermal shock.

4. A burned clay mold plug formed by plastic extrusion in the direction of its axis, upsetting to the form of a truncated cone along the same axis, drying and burning, having throughout itsbody conical laminations whose axes substantially correspond to the axis of the exterior conical surface thereof, the larger circular surface of said plug having been wiped or pressed while wet comprising a smooth hardened skin resistant'to abrasion.

5. A burned clay ingot mold plug formed by plastic extrusion in the direction of its axis and upset to form a truncated cone along the same axis and dried and burned, and adapted to be disposed in the conically tapered bottom hole of an ingot mold with its upper surface exposed to the fluid metal contents of the mold, said plug comprising a solid unitary laminated structure having cohering laminations throughout its body lying substantially normal to said exposed upper surface and constraining the tendency to fracture to the directions of said laminations, the said upper surface of said plug having been wiped or pressed while wet, and comprising a smooth hardened skin containing the ends of said laminations and resistant to abrasion.

ARTHUR C. ES'I'EP.

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