US2049982A

US2049982A - Hot top

Info

Publication number: US2049982A
Application number: US718796A
Authority: US
Inventors: Ernest J Turner; William A Turner
Original assignee: MCLAIN FIRE BRICK Co
Current assignee: MCLAIN FIRE BRICK Co
Priority date: 1934-04-03
Filing date: 1934-04-03
Publication date: 1936-08-04
Anticipated expiration: 1953-08-04

Description

Aug. 4, 1936. E. TURNER ET AL HOT To? Filed April 3, 1934 1 7 I 4 il I 2 z I (/7 v I 1/ v I 11/ IIII LIL Patented Aug. 4, i936 UNHTED STATES PATENT HOT TOP Delaware Application April 3, 1934, Serial No. 718,796

2 Claims.

. This invention relates to a hot top such as frequently is used in connection with ingot molds for confining a molten mass of metal at the upper end of the ingot mold available for feeding into 5 voids or the like created in the course of the solidification of the ingot. The invention provides a. remedy for the difliculty sometimes encountered with bridging of congealed metal across the juncture of the hot top cavity and mold cavity.

A subsidiary feature of my invention is an improvement in the method of producing refractory articles formed with an extremity which does not aiford a stable base; and one object of my invention is to provide an improved procedure for producing such articles in accordance with which the articles may be piled in a kiln by the use of integral pads, the articles fired, andthe pads then broken ofi.

In general, the usefulness of a hot top depends upon its ability to maintain in the molten state a reservoir of metal at the upper end of an ingot mold and to feed molten metal downwardly into the cavities, voids or the like which would otherwise result from the solidification of the ingot.

The hot top is customarily made of material which has high insulating value; and heat flows outwardly and is dissipated from the ingot mold at a considerably greater rate than takes place through the confining walls of refractory matefor the heat of the metal within the lower portion of the hot top by passing around the lower edge of the hot top; and therefore, there is a tendency for the metal in the lower portion of 35 the hot top to congeal, thus forming a bridge,

' while there is a substantial body of molten metal within the hot top above this bridge. It will be apparent, therefore, that it is desirable to prevent such a bridge forming; as the bridge cuts 40 ofi the efiectiveness of the hot top at the point in the solidification of the ingot at which such bridge forms.

In accordance with my invention, I prevent such a bridge forming at the lower end of the 45 hot top by increasing the transverse dimension of the cavity toward the lower end of the hot top; thus making it less likely that the bridge will form, due to the increased size of the space across which the bridge must extend.

50 This improvement may be embodied in a number of forms, as hot tops of a variety of shapes and constructions are commonly used in the pouring of ingots. Two illustrative embodiments are shown in the drawing, in one of which the g walls of refractory material of the hot top are rial of the hot top. There is an avenue of escape solid and are tapered to a wedge-shaped extremity which would interfere with production of such an article in the customary manner. To overcome this difiiculty, bearing pads are formed integrally with the tapered extremity of the article; and 5 when the articles are piled in the kiln, these bearing pads afi'ord a support permitting the articles to be superimposed. When the articles are hard. ened by firing, the pads may be broken off leaving the desired tapered edge. 10

In the drawing which illustrates my invention,

Fig. 1 is a plan view of a hot tophaving compound walls;

Fig. 2 is a sectional view on line II--II of Fig. 1, showing how my invention may be embodied in 15 this type of hot top;

Fig. 3 is a plan view corresponding to Fig. 1 of another type of hot top in which the walls of refractory material are solid;

Fig. 4 is a bottom plan view of a hot top such 20 as shown in Fig. 3 with pads formed integrally with the lower extremity;

Fig. 5 is a sectional view on the line V-V of Fig. 4, a second hot top being superimposed to illustrate how these articles may be piled in a 25 kiln due to the provision of the supporting pads; and

Fig. 6 is a sectional view on the line VI-VI of Fig. 3 illustrating a hot top from which the pads have been broken oiT.

The hot top shown in Figs. 1 and 2 is a modification of a well known type of hot top which has marked elnciency in insulating the mass of molten metal confined at the upper end of the ingot mold. The compound wall of refractory material which surrounds the space for confining the molten mass of metal is made up of an inner shell '6 and an outer shell 8 tied by ribs or webs 9. Vertical air spaces ll extend through the walls and greatly increase the insulating efiect of the 40 hot top. Ribs I2 formed integrally with the refractory wall of the hot top may be engaged by blocks it for supporting the hot top so as to project within the upper end of the ingot mold i5.

While hot tops of this type are frequently chamfered around the internal lower edge, such chamfering raises but'slightly the throat or level at which the minimum cross-section of the hot top cavity begins. Freezing within the throat has been a troublesome problem where the hot top is called upon to feed a large proportion of its supply of molten metal downwardly into the solidifying ingot. This difliculty has been overcome by substantially lifting the throat upwardly within the hot top. As illustrated in Fig. 2, the hot top is made of'such configuration that the space for confining the molten mass of metal is of substantially uniform cross-section down as far as the throat H, the lower portion of the space being enlarged due to the receding walls which surround this portion of the hot top cavity. By thus enlarging the lower portion of the hot top cavity, and preferably by gradually increasing the transverse dimension of this space toward the lower extremity of the hot top, the throat I1 is substantially lifted within the hot top and freezing within the throat so as to cut off the supply of molten metal by formation of a bridge is delayed until substantially all of the available molten metal confined within the hot top has performed its purpose.

Preferably the throat should be lifted about one-third of the height of the hot top, although improved results over the ordinary hot top are .obtained by elevating the throat to a somewhat smaller extent. While the throat may be lifted somewhat more than a third of the height of the hot top, obviously the result of thinning out the walls for a major portion of the height is merely to decrease the insulating value of these walls.

In the type of hot top shown in Figures 3 to 6. inclusive, the refractory walls 20 of the hot top are solid. Ribs or lugs H are formed integrally with the walls 20 for positioning the hot top on the mold in similar fashion as illustrated in Figure 2. In order to increase the transverse dimension of the hot top cavity toward the lower extremity of the hot top, the refractory material in the lower portion of the walls ill is tapered, as illustrated at 23 in Figures 5 and 6. Preferably, the taper is a. gradual taper so as to gradually enlarge the cross-section of the space within the walls 20. Similarly as pointed out in connection with the first embodiment, it is preferable to raise the throat 24 about one-third of the height of the hot top, although variations one way or the other are allowable, as above pointed out.

As the tapered extremity 23 of the hot top does not afiord a suitable rest when superimposing hot tops, it would be difficult to produce these hot.

tops in accordance with the usual kiln practice. This difiiculty has been met by so forming the refractory material as to provide supporting or hearing pads 25 which are integral with the tapered extremity 23. As illustrated in broken lines in Figure 5, the hot tops may be piled in a kiln by virtue of the integral pads 25, which provide stable support for the superimposed articles. A sumcient number of the integral pads 25 will be 5 spaced about the extremity of the hot top to beat the weight of the superimposed articles. As indicated by Figure 5, the hot tops are preferably fired with the tapered extremity uppermost, the hot top next above resting on the bearing pads 25. The hot tops are then fired in the customary manner in a suitable heating chamber, such as the kiln referred to; and after the removal of the hot tops from the kiln, the pads 25 are broken oif. If desired, the refractory material when molded may be scored at the junction of the pad 25 and tapered extremity 23, as shown at 26, to facilitate the breaking off of the pads 25. As indicated at 25a, in Figure 6, the tapered extremity 23 is left with an internal surface which is sub- 15 stantially conical.

In both embodiments of the invention, the refractory walls surrounding the lower portion of the hot top cavity recede, thus substantially lifting the throat upwardly within the hot top. Pursuant to this change in the level at which the minimum cross-section of the hot top cavity begins, the likelihood of congealed metal bridging across the throat is largely eliminated. This is of particular importance where the available supply of molten metal is not substantially larger than the requirements of the ingot mold. In other words, if the capacity of the hot top has been carefully calculated so as not to entail an excessive amount of metal in the head, which must be discarded, the substantial lifting of the throat within the hot top is of marked advantage in making available a sufiicient quantity of molten metal for feeding the pipe or like cavity which would otherwise occur in the ingot.

While we have illustrated and described certain preferred embodiments of our invention, it will be understood that the invention may be otherwise embodied and practiced within the scope of the following claims.

We claim:

1. as an article of manufacture, a hot top having a feeder space surrounded by refractory material tapered from the lower extremity upward 1y for at least a portion of the height of said feeder space with the exception of supporting pads formed integrally with said tapered portion.

2. As an article of manufacture, a hot top having walls of refractory material having the lower portion tapered to a wedge-shaped lower extremity with spaced bearing pads formed integrally with said tapered portion.

ERNEST J. TURNER.

WILLIAM A. TURNER.