US1921729A - Hot top - Google Patents

Description

Aug. 8, 1933. w. M. CHARMAN HOT TOP Filed July 2, 1930 Patented Aug. 8, 1933 UNITED STATES PATENT OFFICE 11 Claims.

This invention relates to improvements in hot tops for ingot molds. The invention has to do primarily with the use in a hot top of a paperlike material for contact with the molten metal,

this material being so constituted as to resist the action of heat to a considerable extent in order to protect the semi-permanent portions of the hot top and to afford good parting surfaces.

One of the objects of the invention is the provision of a relatively cheap material for hot tops or the lining of hot tops, particularly a material that can be readily molded, that possesses sufiicient strength to be self-sustaining, and that constitutes a good heat insulator.

Another object is the provision of a hot top lining that may be formed in one or more pieces and readily and quickly put in place and attached to the casing.

Still another object is the provision of a lining which is adapted to be charred by the action of the heat during an ingot casting operation and thereby weakened, whereby a parting surface, facilitating the stripping of the hot top from the ingot, is formed. 4

A further object is the provision of a hollow metal casing in which a partial vacuum is created, such casing being protected throughout its height by a renewable or temporary lining.

0ther objects and features of novelty will appear as I proceed with a description of those embodiments of the invention which, for the purposes of the present application, I have illustrated in the accompanying drawing, in which Figures 1 and 2 are vertical sectional fragmental views illustrating the invention applied to hot tops having metal casings and refractory heat insulating elements.

Fig. 3 is a similar view of a hot top in which the insulation is accomplished by means of a hollow member in which a partial vacuum may be created and maintained if desired.

Figs. 4 and 5 are similar views of further modifications wherein rigid refractory elements provide the principal insulation.

Figs. 6, 7, 8 and 9 are similar views of hot tops,

each comprising a metal casing, a refractory up per course insulation, and a lower course paperlike renewable lining, and

Figs. 10, 11 and 12 are similar views of three different forms of hot tops constructed entirely of molded, paper-like material.

In Figs. 1 and 2 I have shown at 10 a metal casing which may be round, rectangular, or of whatever shape best conforms with the particular mold with which it is-to be used, and whose lower extremities at least conform to the contour of the section of the ingot mold wherein it has been designed to be used. The casing is of a size to fit within the mold, one portion of which is indicated at 11 in the drawing, the hot top being of the type which floats upon the cast material as the latter shrinks in the mold during cooling and solidification after the pouring operation. In each of the figures'referred to, the casing 10 is provided with an integral inwardly extending ledge 12 running preferably entirely around the casing and adapted to support an upper course refractory 13, made usually in a series of blocks or bricks suitably interfitted so as to be interlocked in position against movement inwardly.

According to the construction of Fig. 1 I apply a flat, fibrous, non-combustible pad 14 of annular form which covers completely the lower edge of the hot top and protects the latter from damage. This pad may be made either partially or wholly of asbestos. The entire inner surface of the hot top and the lower edge surface thereof are then covered by a slow burning, paper-like lining 15, which is preferably made in a single piece molded to the proper shape and fitted rather tightly in place, where it is held by friction or by a suitable adhesive or by suitable fastening means, not shown. This lining 15 is intended to be used but once. It is strong enough to be selfsustaining and is highly resistant to heat, although it may char when the ingot is poured, and thereby afford a nice parting plane, facilitating the stripping of the hot top from the ingot.

In Fig. 2 the pad for the lower edge of the hot top is omitted, and the lining 16 is made thicker and otherwise constructed so as to afford better. insulation than in the case of the lining 15. The lining 16 is mounted and supported in a manner similar to thatdescribed for the lining 15.. As,

indicated in the drawing, it may have an intermediate corrugated layer so as to afford air spaces, or other means for producing a cellular construction might be employed in order to increase the insulating qualities of the lining.

It will be noted that in both of Figs. 1 and 2 the lining 15 or 16, as the case may be, is extended outwardly beyond the casing far enough to contact with and wipe upon the mold wall when the hot top is lowered into the mold. It can be,

and is, made to conform precisely with the contour of the mold wall.

Referring now to. Fig. 3, it will be seen that the metal casing l'l'is provided with a ledge 18. This ledge supports, instead of a refractory as in the previous figures, a hollow metal inner casing member 19, preferably cast in a single piece. The outer casingis vertical rather than tapered upwardly, so that .the inner casing member 19 may be lowered directly into position from above, whether it be made in one or in severalv pieces. Such a hollow member, even when filled with air, forms a good insulator, but its insulating qualities may be improved by exhausting the air from the space within the member, an air valve and pump or hose connection being indicated in the tion which contacts with the ledge 23 is prefer-' drawing at 20. The inner surface of the member 19 and the lower edge surface of the casing 17 are protected by a fibrous lining 21, similar in every respect to the lining 16 above described, and. forming a means of parting, or a shearing plane.

In Fig. 4, the metal casing 22 has an integral ledge 23, upon which is supported refractory elements 24 similar in construction and arrangement to the corresponding elements 13 in Figs. 1 and 2. The ledge 23 on the inner side thereof is provided with two or more openings into which may be driven wooden plugs 25. In preparing the hot top for use prior to each casting operation, these plugs are driven into place after the charred ones have been removed. They are then faced oif flush with the surface of the ledge, and an inner lining member 26 is pushed up into the hot top and fastened by nails 27 driven through the lining into the wooden plugs. This lining member 26 is of paper-like material having the capacity to resist heat, in other words it is similar to that illustrated in Fig. l, but the lower porably made thicker than the upper portion on account of the necessity for especially good insulation at this point as a protection to the metal l d e.

In Fig. 5 the metal casing is marked 28. It has no integral ledge, but instead is provided with a removable and renewable ledge member 29 which is recessed upon its upper and outer edge to receive the lower end of the casing, and is supported by metal fasteners or plugs 30 which extend through perforations in the ledge member and are threaded into registering sockets provided in the casing. The inner and lower surface of the ledge member 29 may be alloyed with or impregnated with chromium or a chromium compound in order to render it especially resistant to deterioration by heat. However, in the 7 event that the ledge should be damaged, it may be replaced at an expense which is relatively small as compared with the expense of replacement of the entire casing. As in the previously described forms of the invention, the ledge serves as a support for upper course refractory members 31. After each heat, an inner lining 32 of paper-like material, molded to have a snug fit within the hot top, is pushed into place and held by friction, adhesive or other suitable means.

The form of the invention shown in Fig. 6 comprises a metal casing 33 having an inwardly extending continuous ledge 34 which supports refractory members 35. These refractory members constitute an, upper course lining, and the lower course lining'consists in this case of an annular molded, preferably single piece, member 36 which protects the ledge 34 and the lower end of the refractory members 35. Its outer edge also conforms in shape to the wall of the mold 11, and wipes against the same. In order to hold the lining member 36 in place upon the hot top, that is until the metal is poured, I provide one or more leaf springs 37, the upper edges of which engage the ledge 34 for support. These springs are bowed-inwardly for a distance, as shown, and the lining member 36 is provided with an external groove which is adapted to receive such bowed portion. When the lining member is pushed into place the springs 37 yield sufficiently to flatten out the bowed portions, and then the latter snap into place in the groove of the lining member. In case the ingot should adhere to the lining member 36 when the hot top is stripped from the ingot, the-springs 37 again yield, or

fail, permitting the lining member to be left behind on the ingot. Before each casting operation the inner surface of the refractory members 35 is preferably coated with some suitable parting compound. For this purpose I have found a mixture of plumbago with water glass or a mixture of graphite foundry facing, silica cement and gluten to be satisfactory.

The form of the invention illustrated in Fig. 7 is quite similar to that of Fig. 6, there being a metal casing 38 having an integral ledge 39 supporting the upper course lining consisting of refractory blocks 40. In this case however the ledge 39 is provided with an internal groove 41 extending preferably all the way around the same, and the lower lining member 42 of paper-like material is provided with a head 43 which is adapted to fit into the groove 41. The lining member 42 possesses sufficient resilience to enable the bead to be sprung into place in the groove and thus retain the lining member in position upon the hot top. I

The modification of Fig. 8 includes a metal casing 44 with an inner ledge 45. Upon this ledge there'is supported a lower renewable lining course 46 of molded, non-inflammable or slow burning material which is provided with occasional integral projections 47 resting upon the ledge. Opposite the projections 47 the refractory lining blocks 48 are cut away to re- 105 ceive the projections, but the blocks .48 otherwise take their bearing upon the ledge. The blocks 48 are preferably recessed at their inner lower corners however, as shown at 49, in order that the lower course lining may be carried up 110 a greater distance than would be possible otherwise. As in the case of Figs. 6 and 7, the inner surfaces of the refractory elements are preferably coated with a-parting compound each time the hot top is put into-use.

In Fig. 9 there is a metal casing 50 having an integral ledge 51 which supports refractory members 52. The lower lining course in this instance is a molded, non-inflammable or slow burning material formed in one or more pieces 120 53, which embrace the inner and bottom surfaces of the ledge and extend outward into contact with the wall of the mold 11. The lower lining member or members 53 may be supported in various ways as, for example, by means of wire ties 54 which are caused to extend through inclined openings 55 in the casing and vertical openings 56 in the lining. When the hot top is stripped from the ingot these fastenings either fail or pull through the charred lining of the lower course. In either event the lining pieces 53, or portions of them, remain upon the ingot.

Figs. 10, 11 and 12 illustrate three somewhat different forms of hot top, in all of which however the hot top is devoid of any metal casing, and consists preferably of a unitary molded article formed of mineral or mineral and vegetable substances intermingled, and is heat resisting to a greater or lesser extent. In each of the forms illustrated in these three figures the hot top is 140 designed to rest upon the mold rather than to be supported upon the metal of the ingot, as in the previously described forms, so as to descend with the ingot when the latter shrinks due to cooling. In Fig. 10 the hot top is supported by a projection 57 which may entirely surround the hot top, or which may occur at intervals only throughout its perimeter. In Fig. 11 there is a recessed mold 58, and the hot top fits down into the mold and rests upon the edge of the recess. In Fig. 12 the hot top rests upon the top of the mold, but there is a paper-like lining element 59 which not only covers the entire inner surface of the hot top but also extends down into the mold for a short distance in order to counteract the tendency of the molten metal to flow upwardly and out at the joint between the mold and hot top.

All of the hot tops shownin Figs. 10, 11 and 12 preferably have rather thick walls that are more or less porous or cellular in order to have a high ratio of strength to weight, and in order to enhance the heat insulating qualities of the material. The present invention is not concerned primarily with the means for producing such porous or cellular structure, but it may be stated that one method which I consider satisfactory for the purpose is to include in the mix or ingredients of the composition to be molded a blowing agent, such for instance as ammonium carbonate. The carbonate should be in a finely divided condition and very thoroughly intermixed with the other constituents of the composition. In the process of molding the hot top, the mold is subjected to heat which causes the ammonium carbonate, NH4HCO3, to form the gases NHaCOa and steam. These gases form bubbles and act upon the mass in a manner analogous to the well known action of baking powders in making baked foods, that is they fill it with cells in which the gases are imprisoned.

On the inner and lower surfaces of the hot top in the structures illustrated in Figs. 10 and 11 there is preferably a relatively dense and impervious layer 60. This may be formed in the molding by coating the corresponding part of the mold with a composition lacking the blowing agent above mentioned, or if preferred it may be obtained by coating the finished article with a suitable liquid or plastic material which will harden when dried, for instance a high temperature cement. In the structure of Fig. 12 the lining 59 of course takes the place of the dense layer 60.

The paper-like material which I employ in the several ways illustrated in the drawing, and above described, comprises primarily a fibrous material which is either inherently fire resisting or which is rendered more or less so by other added materials. Asbestos, because of its inherent non-combustible properties, is a desirable fiber for the purposes of the present invention. Wood pulp and other vegetable fibers may be used to a greater or lesser extent, depending upon the particular character of the results desired. Asbestos fiber and wood pulp may be mixed together in various proportions and pressed into sheets or molded into definite shapes, their fibers being thereby matted together. Mineral fillers of various kinds may be added to the mix. For this purpose I have found the following materials to be satisfactory: silica cement, ground or crushed brick, clay, loam, silicas and ores of various kinds. It is desirable also to use a binder of some sort, particularly where fillers constitute a substantial proportion of the mix. At the present time I prefer to employ sodium silicate for this purpose.

When the paper-like material is otherwise ready for use, particularly where the proportion of vegetable matter is relatively high, I apply to the surface a coating of some plastic or liquid material having fire resisting qualities.

Having thus described my invention, I claim:

1. In a hot top for ingot molds, an inner lower lining member comprising a shell fitted to the inner walls of the hot top adapted to contact with the molten metal, having self-sustaining characteristics, comprising compressed, fibrous, heat resisting material.

2. In a hot top for ingot molds, an inner lower lining member comprising a shell fitted to the inner walls of the hot top adapted to contact with the molten metal, comprising fibrous material and an inorganic filler'material compacted to the extent of being self-sustaining.

3. In a hot top for ingot molds, a lining for the inner lower sides thereof comprising a shell fitted to the inner walls of the hot top adapted to contact with the molten metal, comprising fibrous material compacted to the extent of being selfsustaining, and having a heat resisting coating.

4. In a hot top for ingot molds, a lining for the inner lower sides thereof comprising a shell adapted to contact with the molten metal when the ingot is poured, said shell comprising fibrous material and inorganic filler material compressed to the extent of being self-sustaining and shaped to fit the inner walls of the hot top, and adapted to resist burning so as to space the metal of the ingot from the main wall of the hot top until a shell of solidified metal forms on the ingot.

5. In a hot top, a rigid portion adapted to be placed in operative relation to an ingot mold, and a separable molded, one-piece lining therefor of matted fibrous material fitted to and covering the entire inner andlower surfaces of the rigid portion.

6. In a hot top, a rigid portion adapted to be placed in operative relation with an ingot mold, and a one-piece lining of fibrous preformed material fitted to and covering the entire lower surface of the rigid portion and extending upwardly therefrom along and engaging the inner wall of said rigid portion.

7. In a hot top, a metal casing, an upper course refractory lining therefor, and a renewable lower course fibrous preformed lining covering the lower edge of the casing and contacting with the refractory lining, said lower course lining being adapted to separate from the casing when the hot top is stripped from the ingot.

8. In a hot top, a metalcasing, an upper course refractory lining therefor, and a renewable lower course fibrous preformed lining covering the lower edge of the casing and extending upwardly along the inner side of said refractory upper course.

9. In a hot top of the type that is adapted to be inserted into a mold and to float upon the molten metal therein, a rigid portion adapted to be used repeatedly, and a renewable fibrous portion covering the lower edge of the rigid portion and extending outwardly to wipe against the irmer face of the mold.

10. In a hot top of the type that is adapted to be inserted into a mold and to float upon the molten metal therein, a rigid portion adapted to be used repeatedly, and a renewable fibrous self sustaining portion fitted to and covering the entire inner wall of the rigid portion and extending downwardly and outwardly under the lower edge -of the rigid portion, and outwardly to wipe against the inner face of the mold.

11. In a hot top for ingot molds, a lining for the inner lower sides thereof fitted to the walls of the hot top so as to have a backing thereagainst, said lining comprising a fibrous material,

a refractory material and a binder intimately commingled and molded so as to be self-sustaining.

WALTER M. CHARMAN.

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