US2221130A - Method of making ingot mold plugs - Google Patents

Description

Nov. 12, 1940. c. ESTEP 2,221,130

' METHOD OF MAKING INGO T MOLD PLUGS Original Filed Sept. 3, 1937 A 770 RNA-'75.

Patented Nov. 12, 1940 UNITED :STATES PATE T OFFICE 2,221,130 METHOD or MAKING moor MOLD PLUGS Original application Septemberfi, 1937, Serial No. 162,315- Renewed May 25., 1939. I Divided and this application June 24, 1939, Serial No. 281,002.

3 Claims. (o1. 22-193) This invention relates to a method of making ingot mold plugs and more particularly to a ceramic or a refractory ingot mold plug particularly adapted for advantageous use with a bigend-up ingot mold. The instant application constitutes a division of my prior- Patent No. 2,170,555 filed September 3, 1937, allowed June 9, 1938, and renewed May 25, 1939, renewal Serial No. 162,315.

v In the art of casting ingots there has been a general adoption of the big-end-up type of 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 closed by 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 crushing or abrasion against the wall of the hole, an ingot mold plug formed of burned clay is capable of effecting an efiicient sea The pres- 30 ent invention relates principally to the method of making refractory ingot mold plugs, the latter bein particularly described and claimed in my aforesaid co-pending application.

It is among the objects of my invention to pro- 35 vide a burned clay ingot mold 'plug and method of making the same whereby the plug will with- .deaerating of the extruded mass.

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 a burned clay mold plug characterized by smooth troweled outer surfaces especially resistant to spawling 6' and cracking. It is also among the objects of my invention to provide a method for making a mold plug in accordance with the preceding object. Further objects and advantages relating to economies of manufacture and characteristics of the 10 finished mold plug will appear from the following description and the appended drawing in which- Figure 1 is aview of a clay extrusion apparatus suited to extrude laminated cylindrical stock employed in my invention; 5

Figure 2 is a sectional view with parts broken away of an upsetting or molding apparatus made according to my inventio Figure 3 is an enlargedsectional view of the relief mechanism employed in the upsetting or molding apparatus; I

Figure 4 is a transverse sectional view (taken 'alongthe line 44 of Figure 5) of a mold plug constructed according to my invention;

. Figure 5 is a plan view of the mold plug; '25

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 objectsoutlined above comprises extruding wet clay stock of round cross section such as 4 inFigure 1. Preferably the clay stock is extruded from an anger 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 atmosphere 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 In addition to insuring against deaerating the mix should 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 7 in the usual manner and forced "by an auger through the forming throat l3 and extrusion die l2. The extruded stock 4 is severed by Wire cuttersor Figure 2 a cylindrical mold plug 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 stock 4 and the cutting 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 substantially to the shape of the finished mold plug. A backup or ejector plunger 24 is positioned within the bore 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 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.

I have found that by upsetting a cylindrical clay slug as above described that the exterior surface of the article is improved by the formation of a hard, tough spawl-resistant cover. The pressure upon the wet clay slug appears to bring moisture to the outer surface of the upset article and upon burning a thin cover or skin is formed which is resistant to spawling. .The spawl 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 is preferably effected so as to effect no disturbance of the 1aminated 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 effect 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, skin-like cover which is resistant to spawling and thus contributes to the prevention of nonmetallics being carried up into the ingot during the pouring thereof.

Due to the fact that as a practical matter in commercial production it is difficult 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 difficult 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 l9 to close the lower end of the upsetting centrally apertured as at 25 (Figure 3) and carries in said aperture a piercing tool 21 which is normally urged upwardly to the limit of a slot such as 28 by a spring 29. Each of the cylindrical slugs 6 is initially cut so as to provide a volume 5 of material less than the volume of the 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 21, 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 of the cylindrical bore 26 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 theplastic 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. 1 Y

The steps which include the cutting and up- 4. setting of the plastic clay blank are preferably carried out in a manner which will not appreciably disturb the cylindrical laminations in the slug so that the finished upset plug will in effect comprise a series of tapered tubes more or less {$5 distinguishable from each other by laminations such as 16 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 (50 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 35 and driven into the base of the ingotmold to close the opening L5? 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. Q9 The impact at the upper surface of the plug may be sufficient to effect a slight 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 I5 tight seal against the molten metal and form a 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 @713 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 that a mold plug of my invention could be 75 driven into the opening 36 with such force that the plug is fractured two or three times on different concentric conical surfaces [6 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 less of the cause of plug fracture the usefulness of the plug is not destroyed as long as the fracture is restricted to concentric surfaces such as It. desirable characteristics of a broken or spawled particles of the plug and carry the same up into the ingot. An ingot carrying particles of non-metallic is obviously defective for rolling purposes. It will be observed that due 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 may be entitled I claim: 1. That method of making an ingot mold plug which comprises extruding a length of clay stock which comprises extruding clay stock, cutting said stock transversely to produce blanks proportioned into conically surfaced plugs by compressing said blanks in the direction of extrusion and burning said plugs,

3. That method

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