US3046625A - Hot top and wiper strip construction - Google Patents

Description

y 1962 J. c. CARPENTER 3,046,625

HOT TOP AND WIPER STRIP CONSTRUCTION Filed 001,- 15, 1960 IN VEN TOR.

JOEL C. CARPENTER BY W MW r 3,946,625 Patented July 31, 1962 3 046 625 nor TOP AND wnisn srnrr coNsTRUcTioN Joel C. Carpenter, Chagrin Falls, Ohio, assignor to Oglebay Norton Company, Cleveland, Ohio, a corporation of Delaware Filed Oct. 13, 1960, Ser. No. 62,384 11 Claims. (Cl. 22-147) This invention relates to a hot top and particularly to an improvement in the wiper strip arrangement [for the hot top.

Composite reusable hot tops of the floating type are inserted into the upper end of an ingot mold and temporarily supported therein for the pouring of molten metal into the mold and hot top to produce an ingot as is well understood in the art. Efforts are made to keep the clearance space between the outside of the hot top particularly at its refractory bottom ring and the inside wall of the ingot mold to a minimum. However, mold manufacturers allowable tolerances are such that said clearance space may vary substantially in width due to variations in the size of the ingot mold or the opening at the top of the ingot mold.

During .a pouring operation the molten metal that normally flows into the clearance space between the outside of the hot top and the inside wall of the ingot mold must be sealed again-st rising too far in said space or overflowing the upper edge of the mold. If the molten metal rises too far in the clearance space and then solidifies therein difficulty will be experienced in stripping the hot top from the sinkhead of the solidified ingot. If the molten metal rises in the clearance space and overflows the top of the ingot mold such overflowing metal when solidified will produce what is known as hanger ingots, that is ingots which are not free to contract relative to the mold as the ingot solidifies and this condition would tend to produce undesirable hanger cracks in the ingot.

The ideal situation for the effective and eflicient teeming of the molten metal is therefore to provide as complete a seal as possible against undesirable rising of the molten metal in and through the clearance space.

In those instances wherein the clearance space between the hot top and the inside wall of the mold is a close one it is relatively easy to effect a good seal again-st the molten metal rising too far in or overflowing such clearance space, although the operation of inserting the hot top into the ingot mold under this condition will be much more difiicult.

In those instances wherein the clearance space between the hot top and the inside wall of the ingot mold is large it is, of course, more diflicult to effect the necessary seal against the rising of the molten metal in said space although under this condition the operation of inserting the hot top into the ingot mold may be relatively easy.

Inasmuch as the size of the hot top and its refractory bottom ring can be closely controlled, the clearance space between the outside of the hot top and the inside wall of the ingot mold depends entirely on the size of the opening at the top of the mold.

In an efiort to obtain the optimum condition just referred to resort has been had to the use of what is known in the art as wiper strips. These wiper strips are usually formed of rather flexible thin sheet metal that may be separate from or secured to the refractory bottom ring and they have a bottom ring engaging or attaching portion which, in turn, has an integral wiper lip extending angularly from an edge of said portion outwardly of the periphery of the bottom ring and adapted to engage the inner wall of the ingot mold as the hot top is inserted into the mold and is positioned therein during a pouring operation.

The attaching portion of the wiper strips may consist of a single planar strip contacting a surface of'the refractory bottom ring or the attaching portion of the wiper strip may consist of angularly disposed integral parts contacting angularly disposed surfaces of the refractory bottom ring.

During a pouring operation as the molten metal enters the clearance space between the hot top and the inner wall of the ingot mold the pourer should momentarily interrupt the pouring operation to allow the molten metal in said space and in contact with the wiper lip of the wiper strip to suificiently solidify to form a seal against further rising of the metal in the clearance space. This solidification of the molten metal in the clearance space is facilitated by its contact with the wiper lip of the wiper strip since the metal wiper strip produces a chill in the molten metal that has risen into the clearance space.

The wiper lip of these wiper strips is of such width as to attempt to span across the clearance space between the hot top and the inner wall of the mold and as the hot top is inserted into the open top end of the mold said lip should flex and accommodate itself in the clearance space.

However, in those instances wherein the hot top is used with a mold having a small opening the wiper lip of the wiper strip may extend so far over the top of the mold as to prevent the entry of the hot top into the mold thereby causing the hot top to be suspended from or hung on the top of'the mold by the wiper'lip.

Conversely, in the situation wherein the hot top is used with a mold having a large size opening the wiper lip of the wiper strip may not extend outwardly from the hot top sufiiciently far to engage the inner wall of the ingot mold when the hot top is inserted therein thereby preventing the desired seal.

The present invention contemplates a hot top and wiper strip construction such that the wiper lip of the wiper strip will extend outwardly from the periphery of the hot top and its bottom ring a sufficient distance to assure engagement of the lip with the inner wall of the ingot mold when the clearance is large and yet said lip and the attaching portion of the wiper strip will be free to yield and flex as the hot top is inserted into. the ingot mold when the clearance is small so as to conform itself to the clearance space between the hot top and' clearance space between the hot top and the inner wall of the ingot mold and therefore avoids likelihood of hanger ingots or of hot top stickers which prevent the removal of the hot tops from the sinkhead of the solidified ingot.

The invention more specifically contemplates interposing between the hot top structure and the wiper strip in the zone of the junction between the attaching portion and the wiper lip of the wiper strip yieldable backing material which functions initially to'cause the wiper lip to be disposed in maximum extended position so as to assure its engagement with the inner wall of ingot molds having the larger size openings but which backing material yields to assure flexing of the wiper lip and attaching portion when the hot top is inserted into the mold. 1

In accordance with the invention the term yieldable backing material is intended to cover compressible material as well as displaceable material. The backing ma V terial also enhances the chilling effect ofthe wiperst rip when the molten metal rising in the clearance space between the hot top and the ingot mold contacts the wiper strip and this, of course, increases the efliciency of the wiper strip and hastens the desired solidification of the metal in the clearance space to form the required seal.

Although the invention at least in certain of its aspects can be used in connection with various forms of wiper strips, its use will be referred to herein in connection with that form of wiper strip wherein the attaching portion from which the wiper lip extends engages the outer periphcry of the bottom ring since the invention is particularly useful with said type of wiper strip.

In a hot top construction wherein the refractory bottom ring nests in the attaching portion of the wiper strip which engages and extends vertically of the outer periphery of the bottom ring, the wiper strip is relatively stiff, particularly at the junction between the attaching portion thereof and the integral angularly extending wiper lip. This is true even though the wiper strip may be notched or slit at critical locations to increase its flexibility. In this type of construction the engagement of the attaching portion of the wiper strip with the outer periphery of the refractory bottom ring prevents the attaching portion itself from flexing, with the result that entire reliance must be placed on the limited ability of the wiper lip itself to flex in accommodating itself to the inner wall of the mold.

The invention further contemplates in those constructions wherein the attaching portion of the wiper strip contacts the bottom ring, particularly the outer periphery of the ring, relieving a portion of that part of the bottom ring which heretofore was contacted by the attaching portion of the wiper strip so that the attaching portion of the wiper strip is made susceptible of movement inwardly toward said part of the bottom ring during the insertion of the hot top into the ingot mold and thus supplements the flexing of the wiper lip of the wiper strip in allowing the wiper lip to properly accommodate itself to the inner wall of the mold.

Specifically where the attaching portion of the wiper strip surrounds and contacts the outer periphery of the bottom ring, a portion of the vertical surface of said periphery of the bottom ring is relieved or beveled inwardly and upwardly from a point at or above the bottom outside edge of the ring. This provides a space between a part of the attaching portion of the wiper strip and the bottom ring so that said attaching portion may move or flex into said space, particularly when the hot top is being inserted into a mold with a smaller size opening. The provision of said space behind the attaching portion of the wiper strip lessens the chilling effect of the wiper strip on the molten metal and this might lessen the effectiveness of the seal, however, the yieldable backing material previously referred to fills said space and functions to increase the chilling effect of the wiper strip and also acts to force the attaching portion of the wiper strip outwardly from the periphery of the bottom ring and thus move the wiper lip outwardly a maximum distance from the bottom ring. This enables the hot top construction to be used with a relatively large size mold and still have the wiper lip engage the inside wall of the mold and provide maximum efiiciency for the sealing off of the molten metal in the clearance space between the hot top and the mold.

The specific details of and the advantages in the hot top construction broadly described above will be pointed out in the following description of an embodiment of the invention which is illustrated in the accompanying drawing which forms part of this specification and wherein- FIG. 1 is a sectional view through a hot top construction embodying the invention and shows said hot top as it is being inserted into the open upper end of an ingot mold, a portion of said mold being indicated in section,

FIG. 2 is a view on a larger scale of the lower right hand portion of FIG. 1,

FIG. 3 is a view similar to FIG. 2 but shows the hot top inserted farther into the ingot mold and the free edge of the wiper lip of the wiper strip engaging the inner wall of the ingot mold,

FIG. 4 is a top plan view of the refractory bottom ring and wiper strip shown in the previous views and detached from the hot top, and

FIG. 5 is a separated elevational view of the refractory bottom ring and wiper strip shown in FIG. 4.

Referring to FIG. 1, the composite reusable floating hot top illustrated therein comprises a metal casing formed, in this instance, of lower and upper parts 10 and i1 suitably secured together as is well understood in the art. The metal casing of the hot top is lined with a suitable refractory linging 12 which may be of any well known form. The refractory bottom ring 13 is secured to the lower end of the hot top by attaching clips 14 as is well understood in the art. The wiper strip shown, for purposes of illustration, has an attaching portion composed of a part 15 which underlies and contacts the bottom of the bottom ring and a part 16 integral with the part 15 and extending substantially at right angles thereto and vertically of the outer periphery of the bottom ring. The wiper lip 17 of the wiper strip is integral with the part 16 and extends angularly and outwardly from the upper edge of said part 16. The open upper end of an ingot mold 18 is indicated in FIGS. 1 through 3.

The hot top with the bottom ring and wiper strip at tached thereto and prepared for a pouring operation is inserted into the open upper end of the ingot mold initially a predetermined distance and is held in inserted position by means of wooden blocks (not shown but well known in the art) until a period in the pouring operation when said blocks are destroyed or knocked out of position and thereafter the hot top rests on the metal in the ingot mold and can have limited movement relative to the mold during the solidification of the ingots as is well understood.

When the hot top is inserted into the mold the wiper lip 17 of the wiper strip is adapted to accommodate itself to the inner wall of the mold and to engage the latter as indicated in FIG. 3 and for a purpose understood in the art and more fully referred to hereinafter.

Although the invention in all or some of its aspects may be used advantageously in connection with various wiper strip and hot top constructions, it will be explained herein as embodied in the bottom ring and wiper strip combination disclosed in the copending Urmetz and Carpenter application Serial No. 62,757, filed October 14, 1960 inasmuch as it has particular utility when so employed. Only one embodiment of the bottom ring and wiper strip combination shown in said Urmetz and Carpenter application Serial No. 62,757 is illustrated herein but it will be understood that the invention could be employed in connection with the other embodiments of the bottom ring and wiper strip combination shown in said Urmetz and Carpenter application as will be later pointed out.

As already stated the attaching portion of the wiper strip illustrated and composed of the parts 15, 16 and 17 has the bottom ring 13 nested therein with the part 15 extending beneath and contacting the underside of the bottom ring and the part 16 extending vertically of and contacting the outer periphery of the bottom ring. The bottom ring and wiper strip combination is such that the combination is handled and attached as a unit to the hot top casing by means of the attaching clips 14. The wiper strip is shown as constructed of a continuous stamping extending completely about the bottom ring. However, it will be understood that the wiper strip could be formed of separate sections having their adjacent ends overlapping and secured together as illustrated in a further embodiment disclosed in said Urmetz and Carpenter application Serial No. 62,757.

The wiper strip is formed of thin sheet metal having a substantial measure of flexibility. However, to increase For the flexibility of the wiper strip, and particularly the wiper lip 17 thereof, it may be provided with a number of spaced slits particularly at the-corners, these slits being indicated in FIG. 4 at 19, it being understood, however, that the slits may vary in number from the four slits shown depending on the particular configuration of the ring wiper combination and the mold with which it is used.

Also the wiper lip 17 is provided with slots. or cut outs 19a through which the attaching clips 14 extend.

In some instances the outer periphery of the bottom ring and the wiper strip are fluted or sinuous and it is desirable to slit the wiper lip 17 between the curved sections of the flutes, as well as at the corners to increase the flexibility and enable the wiper lip to conform to the contour of the inside wall of the ingot mold as the hot top slides into place.

As previously mentioned, an embodiment of the bottom ring and wiper strip combination disclosed in said Urmetz and Carpenter application Serial No. 62,757 includes a wiper strip formed of separate sections, the adjacent ends of which overlap and are secured together and this preferably is at the corners of the wiper strip.

The flexibility of the wiper strip formed of united sections as last referred to can be .maintained by joining the overlapping adjacent ends of the wiper strip sections together only at a single point near the junction between the part 16 and the part 15 of the attaching'portion of the wiper strip as this enables the 'overlap between the upper surfaces of the parts 16 and the overlap. between the Wiper lips 17 to be capable of relative movement, care being taken to provide sufficient overlap at the corners 'to prevent any danger of ,an opening occurring between the overlapped portions when the wiper lip 17 is in maximum extended position with respect to the periphery of the bottom ring.

The wiper strip illustrated is, because of its angular shape in cross section, less flexible than is desirable and consequently it is proposed to notch or slit-the wiper lip 17 at spaced locations as previously referred to, and also to similarly slit or notch the horizontal part 15 of the attaching portion of the wiper strip. This arrangement increases the flexibility of the wiper strip. The flexibility of the wiper strip in the bottom ring combination illustrated, wherein the vertical part 16 of the attaching portion of the wiper strip surrounds and engages the periphery of the bottom ring is lessened, inasmuch as said vertical part 16 being backed up by the bottom ring cannot move 16 of the attaching portion of the wiper strip to have. movement laterally relatively to the bottom ring. This provision is accomplished by providing the periphery of the bottom ring with a relief or beveled surface portionv 20. This relief or beveled surface 20 may extend from or above the lower outside edge of the bottom ring and upwardly to the top of the bottom ring. Preferably the relief or beveled surface 20 will have its lower starting location spaced somewhat upwardly from the lower outside edge of the bottom ring so as to provide a peripheral bottom ring surface that is engaged by the lower portion of the part 16. The relief or beveled surface 20 on the periphery of the bottom ring provides of course a space between said periphery and the inner side of the part 16 of the attaching portion of the wiper strip. Consequently when a hot top equipped with the bottom ring and wiper strip combination thus constructed is inserted into an ingot mold and the wiper lip 17 is flexed in accommodating itself to the inner wall of the mold, the part 16 of the attaching portion of the wiper strip can have limited inwall of the mold and provide the requisite seal.

ward movement because of said space and thus the flexing of the wiper lip is supplemented by inward movement of the part 16. This arrangement has been .found to greatly facilitate the insertion into a tight mold of a hot top equipped with the bottom ring and wiper strip combination. V r

The provision of a space behind the part 16 of the wiper strip might tend to reduce the chilling effect or heat absorption of the wiper strip upon or from the molten metal entering the clearance space between the hot top and the inner wall of the ingot mold. In order to prevent this and also to maintain the part 16 of the wiper strip in its most outward position with a resultant outwardpositioning of the wiper lip 17 the space between the relief or bevel surface 20of the periphery of thebottom ring and the part 16 is filled with a pressure'yieldable backing material 21 which, as previously defined, may be either a compressible material or a displaceable material. As illustrative .of a suitable material 21 reference is made to steel wool, asbestos rope or other fibrous compressible materials. In addition, a displaceable mate-: rial 21 can be used as, for instance, a flowable or viscousmaterial can be employed.

The pressure yieldable backup materialll becausejof. its composition and texture when not subjected to yield: ing pressure functions to maintainor force the pa'rt716 of the attaching portion of the wiper strip and the wiper lip 17 thereof to their outermost position as clearly indi-- cated in FIG. 2. Then when the hot top with the bottom ring and wiper strip combination is inserted farther into the ingot mold as, for instance, to the position indicatedin FIG. 3, the wiper lip 17 will be flexed upwardly and the part 16 will be pressed inwardly of the space enabling; the wiper lip 17 to readily accommodate itself to the infier' e movement of the part 16 of the wiper strip will exert pressure on the backup material 21 and since said material is yieldable it will either be compressed or displaced to allow; such movement of the part 16. f

From the foregoing it will be seen that when the hot top equipped with the bottom ring and wiper strip com-' bination is inserted into a reasonably large mold, the wiper lip 17 being forced to its maximum outward position by the pressure yieldable backup material, will engage the inner wall of the mold and thus assure maximum possibility of obtaining a good seal when the molten metal is teemed up through the clearance space between the, hot top and mold, such possibility of a good seal beingin-- creased by the enhanced chilling elfect on this molten metal produced by the backup material in combination. with the wiper strip. 7 1

When a hot top equipped with the bottom ring and, wiper strip combination is inserted into a tight ingot mold; the wiper lip 17 will first engage the top corner edges of the ingot mold but because ofthe angle of engagementthe wiper lip 17 will be displaced upwardly and inwardly;

as the hot top moves downwardly in the mold. In addition, the vertical part 16 of the wiper strip will be pressed inwardly against the pressure yieldable backup material 21 and therefore because said material is readily com-' pressed or displaced, the wiper strip will easily'conform to the ingot mold as the hot top movesdownwardly, into its final position. This assures easy insertion of the'hot top in the mold together with maximum possibility of effecting the required seal for the clearancespace betweenr the hot top and inner wall of the ingot mold. a

Although a particular embodiment of the invention" has been illustrated and described it willbe understood? that the invention is applicable to other forms of, wiper;

1. In a reusable, composite, floating hot top structure including a metal casing and a refractory bottom ring connected to said casing, a wiper strip having an attaching and bottom ring engaging portion and an integral wiper lip extending angularly from an edge of said portion and outwardly of the periphery of the bottom ring, and pressure yieldable backing material interposed between said structure and said wiper strip and extending substantially completely around said structure in the zone of the junction between said portion and said wiper lip of the wiper strip.

2. In a hot top structure as defined in claim 1 wherein said bottom ring is shaped to provide an intervening space between it and part of said attaching and bottom ring engaging portion of said wiper strip and extending substantially completely around said bottom ring while said pressure yieldable backing material is located in said space.

3. In a hot top structure as defined in claim 2 wherein the outer periphery of said bottom ring is provided with an inwardly relieved or beveled surface extending substantially completely around said ring while said attaching and bottom ring engaging portion of said wiper strip engages said bottom ring and overlies in spaced relationship the inwardly relieved or beveled surface on the periphery thereof.

4. In a reusable composite floating hot top structure including a metal casing and a refractory bottom ring and wiper strip unit connected to said casing, said unit comprising a refractory bottom ring having its outer periphery provided with an inwardly beveled surface extending upwardly from a point adjacent to but above the lower outer edge of the bottom ring and extending sub stantially completely around said periphery, a wiper strip having an attaching portion including a horizontal part engaging the underside of the bottom ring and a vertical part integral with said horizontal part and engaging the outer periphery of the bottom ring below said point and overlying and spaced from said inwardly and upwardly beveled surface thereof above said point, said vertical part of said wiper strip having integral therewith at its upper edge an outwardly and angularly extending wiper lip, and pressure yieldable backing material interposed between said beveled surface of said bottom ring and said wiper strip and extending substantially completely around the hot top.

5. A bottom ring and wiper strip unit adapted to be secured to the lower end of the metal casing of a reusable composite floating hot top and comprising a refractory bottom ring provided on its outer periphery and extending downwardly thereof from its upper casing engaging side with a beveled surface extending substantially completely around said periphery, a wiper strip having an attaching and bottom ring engaging portion fitting the outer periphery of said bottom ring and overlying in spaced relationship the beveled surface thereof, said attaching portion of said wiper strip having at its upper edge an integral angularly and outwardly disposed wiper lip, and pressure yieldable backing material interposed between said wiper strip and said beveled surface of said bottom ring and extending substantially completely around said ring.

6. A bottom ring and wiper strip unit as defined in claim 5 wherein said attaching and bottom ring engaging portion of said wiper strip includes a horizontal part underlying and contacting the underside of the bottom ring and a vertical part contacting the outer periphery of the bottom ring and overlying in spaced relationship the beveled surface thereof and having the wiper lip at its upper edge.

7. In a reusable composite floating hot top structure adapted to be inserted into an ingot mold and including a casing and a refractory bottom ring connected to the lower end of said casing, said bottom ring having a tapering relief extending inwardly of its outer periphery and substantially completely around said ring, and a wiper strip of sheet material having an attaching and bottom ring engaging portion and an integral wiper lip extending from an edge of said portion and outwardly of the periphery of the bottom ring, said attaching and engaging portion having a part extending from the junction between said portion and said wiper lip and which part overlies said relieved portion of said bottom ring and can move into the space provided by said relieved portion when the wiper lip is subjected to forces incident to its engagement with the mold during the insertion of the hot top structure into the mold, wherefore such insertion is facilitated due to the ability of said part to move into said space.

8. In a hot top structure as defined in claim 7 wherein the tapering relief on the outer periphery of said ring is formed by a beveled surface extending upwardly and inwardly from a point on the outer periphery of said bottom ring while said attaching and bottom ring engaging portion of said wiper strip contacts the outer periphery of the bottom ring and said part of said wiper strip portion overlies in spaced relation said beveled surface and said integral wiper lip extends from the upper edge of said part.

9. In a hot top structure as defined in claim 8 wherein said attaching and bottom ring engaging portion of said Wiper strip includes an integral flange underlying and engaging the lower side of the bottom ring.

10. A bottom ring and wiper strip unit for a reusable composite floating hot top structure and comprising a refractory bottom ring having an outer periphery relief portion completely around said ring and a wiper strip of sheet material mounted on said bottom ring and having an attaching and bottom ring engaging portion and an integral wiper lip extending angularly from an edge of said portion and outwardly of the periphery of the bottom ring, said attaching and engaging portion having a part extending from the junction between said portion and said wiper lip which overlies said relieved portion of said bottom ring and which part can move into the space provided by said relieved portion when the unit is mounted on a hot top and the wiper lip is subjected to forces incident to its engagement with the mold during the insertion of the hot top into the mold.

ll. Abottom ring and wiper strip unit as defined in claim 10 and wherein said relieved surface portion of the bottom ring is provided with a beveled surface on the outer periphery of the ring extending upwardly and inwardly from a point on the outer periphery of the ring, while said attaching and engaging portion of the wiper strip surrounds and contacts the outer periphery of the ring and said part thereof overlies said beveled surface in spaced relationship thereto.

References Cited in the file of this patent UNITED STATES PATENTS 1,997,677 Charman Apr. 16, 1935 2,914,824 Marcec Dec. 1, 1959 FOREIGN PATENTS 548,988 Great Britain Nov. 2, 194-2

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