US3432138A - Ingot mold with opposed exothermic sideboards - Google Patents

Abstract

921,274. Ingot moulds. FOSECO INTERNATIONAL Ltd. Aug. 23, 1960 [Dec. 3, 1959], No. 29160/60. Class 83 (1). An ingot mould for casting killed steel, and particularly a big-end down mould, 10 has a hot top comprising two slabs 18 of heat-producing material held in spaced-apart relation and tightly against the side walls, as by rods 46 or wedges 54, or both. A device 25 for inserting the slabs comprises a member 26 with depending partitions 28, 29, 30, and engages on top of the slabs by shoulders 36. Vertically slidable U- pieces 39 hold the device between the pair of slabs and move upwardly as the slabs enter the mould. The wedging rods 46 are releasably supported in slots in shafts 48 which are rotated by means engaging their ends 50 when the slabs are in position, to wedge the rods between the slabs. The device 25 is then removed upwardly, the rods 46 disengaging from the shafts 48. A granular heat-producing material may be added to the top of the melt. Specification 627,678 is referred to.

Description

March l1, 1969 H. D. sHEPHARD, JR., ETAL 3,432,138

INGOT MOLD WITH OPPOSED EXOTHERMIC SIDEBOARDS Filed Sent. 8 1959 United States Patent O 3,432,138 INGGT MOLD WITH OPPOSED EXOTHERMIC SIDEBOARDS Harry D. Shephard, Jr., Pittsburgh, Pa., and Norman J. Griflths, deceased, late of Vanderbilt, Pa., assignors, by mesne assignments, to Foseco, Inc., Cleveland, Ohio, a corporation of New York Filed Sept. 8, 1959, Ser. No. 13,673 U.S. Cl. 249-106 Int. Cl. B22d 7/10 The present invention relates to the production of steel and more particularly to the casting of killed steel in big end down ingot molds. This invention further relates to an improved apparatus for hot topping ingot molds finding particular but not exclusive use in the production of lled steel ingots.

Killed steel ingots for use in the manufacture of wide sheet steel have conventionally been cast in either of two ways: 1) in big end up molds using one of the conventional methods of hot topping such as clay hot tops or refractory lined cast metal hot tops; (2) in big end down molds without any hot tops at all. The use of big end down molds for the casting of ingots has a substantial advantage with respect to handling of the ingots and removal of the molds from them.

When using a big end down mold for killed steel without a hot top a large primary pipe cavity is left in the top of the ingot as a result of the normal shrinkage of the steel. In this practice, the average prime steel yield is somewhere in the neighborhood of 72 to 73%. Generally only 76% of an ingot made by this practice can be considered sound, and after a 4% crop from the bottom of the ingot the prime yield is reduced to about 72% for the manufacture of Wide sheet steel.

14 Claims When using a big end up mold with a conventional hot top, a hot top volume of about 14% excess steel is necessary to produce a sound body in the ingot. With the normal 4% bottom crop an average yield of about 82% is obtained with the hot topping practice. As mentioned above, however, the big end up hot topped ingot procedure is subject `to a substantial disadvantage when it comes to handlingand removing the ingot from the mold. The hot top must be removed and the mold must be inverted, both of which steps require extra handling procedures.

It is the primary object of the present invention to provide an improved hot topping for ingot molds. More specifically, it is an object to provide an improvement of the foregoing type which finds particular use in the hot topping of big end down open top slab ingot molds.

Another object of the present invention is to hot top big end down open top ingot molds without using a separate hot top casting or the like. Still another object is to hot top a mold in a manner which is simple and economical and which at the same time increases the yield of sound ingots cast.

A further object of the present invention is to provide a hot topping for ingot molds of the foregoing character in order to add suflicient heat to the ingot mold to enable fully killed steel to be cast therein. More specifically, it is an object of the invention to provide an improvement of the foregoing character by which heat is added to the ingot mold, and the cross sectional area of the mold top is reduced to form a feeder head. A related object is to cast killed steel ingots in which a single step continuous pour can be employed.

3,432,138 Patented Mar. 11, 1969 A more specific object of the present invention is to mount slabs of exothermically reacting material in position within the mouth of a lbig end down open top ingot mold for use as a hot top when casting fully killed steel.

Other objects and advantages of the present invention will become apparent as the following description proceeds taken in connection with the accompanying drawings wherein:

FIGURE 1 is a perspective view of a big end down ingot mold the upper open end of which is hot topped in accordance with the present invention.

FIG. 2 is a perspective View of a slab or side board of a refractory backed exothermically reacting material suitable for mounting in an ingot mold of the type shown in FIG. l.

FIG. 3 is a fragmentary plan view of the ingot mold shown in FIG. 1.

FIG. 4 is a Vertical section view ot' the upper end of the ingot mold of FIG. 1 and illustrating slabs of exothermically reacting material, of the type shown in FIG. 2, mounted within the open mouth of a big end down ingot mold.

While a certain illustrative method and modified form of apparatus have been shown in the drawings and will be described below in considerable detail, it should be understood that there is no intention to limit the invention to the specific method or apparatus shown and described. On the contrary, the intention is to cover al1 modifications, alternative constructions, equivalents and uses falling within the spirit and scope of the invention as expressed in the appended claims.

The present invention finds particular, but not exclusive utility for casting ingots of killed and semi-killed steel. The distinctions between killed, semi-killed, rimmed and capped steel are described in detail in The Making, Shaping and Treating of Steel, 6th ed., United States Steel Co., Pittsburgh, Pa. (1951). So far as the discussion of ingot casting and types of ingot structure pertain to this invention, the disclosure in this book is incorporated herein by reference.

Briefly, a killed steel ingot is produced by casting into an ingot mold a steel having a uniformly low level of oxygen content. This is conventionally done by deoxidizing the steel sufficiently so that the metal lies perfectly quiet when poured into an ingot mold and there is no evolution of gas from the mold. The shrinkage of metal which occurs on solidication causes a slightly concave top and large cavities below the top often separated by bridges. The cavities and concave top together constitute what is termed pipe In conventional practice, killed steels are usually poured into hot topped molds of the big end up type or into big end down molds which are not hot topped. An illustrative big end down open top mold is shown in U.S. Patent 2,871,532, issued Feb. 3, 1959 to M. H. Gathmann.

The present invention is concerned with hot topping ingot molds and finds particular but not exclusive utility for hot topping big end down open top ingot molds for use in casting ingots of killed steel. Referring to FIG. 1 of the drawings, an ingot mold of this type is there shown which comprises a mold 10 supported on a stool 11. The mold is generally rectangular or oblong in shape, having two long side walls 14 and two short end walls 1S defining a mold cavity. The interior wall surfaces of the mold may have Vertical corrugations 16 therein. The inner walls of the mold taper downwardly and outwardly and the walls of the mold are generally thicker at the bottom than at the top.

In accordance with the present invention, there is supported within the open mouth of the mold, along the two long sides 14 thereof, a pair of slabs or side boards 18 of heat producing exothermically reacting material. These slabs 18 are held apart so that they rest tightly against the inner surface of the side walls 14 of the mold. It has been found that the shorter end walls of the mold need not be covered with a slab of heat producing material.

The heat producing slab is preferably a composite slab (FIG. 4) comprising a layer 19 of a refratcory backing material and a layer 2)` of a moldable exothermically reacting substance.

One illustrative moldable exothermically reacting composition which may be employed is disclosed in U.S. Patent 2,591,105. Compositions produced as described in this patent are available under the trademark Feedex from Foundry Services, Inc. of Cleveland, Ohio.

The exothermically reacting material described therein is a composition formed of an oxidizable metal such as aluminum with an oxidizer such as iron or manganese oxide in an amount substantially less than that amount required to react stoichiometrically with, that is, cornpletely oxidize, the aluminum. The composition also contains a fluoride compound to facilitate the start of the reaction (upon contact with molten metal) and to facilitate maintaining the reaction to completion. The patent gives the following composite range and a preferred cornposition for use with steel castings:

1 Remainder.

For a more detailed description of such exothermically reacting material reference should be made to Patent No. 2,591,105.

The slabs are prepared in any suitable manner. For example, a slab may be constructed by first placing in a suitable mold a granular refractory material such as a sand or refractory grog mixed with a suitable binder. The configuration of the bottom of the mold is preferably the same as that of the ingot mold wall to which the slab will be applied. Thus if the ingot mold walls are corrugated, the refractory layer should be so formed as shown in FIG. 2. Appropriate steel reinforcing frames 21 (as shown in FIG. 4) are inserted into the refractory and a plurality of hooks or eyes 22 are mounted therein so as to extend from one longitudinal edge of the slab thereof. The refractory is hardened, at least partially, and then a layer of the above described exothermically reacting material is placed therein. The entire slab is then fired at a temperature below that which will cause the exothermically reacting material to ignite but high enough to set the binder. Alternatively, a cold process binder such as a CO2 gas hardenable silicate binder may be employed.

For purposes of holding the slabs apart and tightly against the mold walls so as to prevent molten metal from flowing between the slabs and the mold wall, a pair of low carbon steel bars 46 are wedged tightly between their opposing faces as shown in FIG. 4.

The bar 46, which is slightly longer than the spacing between the heat producing slabs, is wedged tightly between the heat producing layers as shown in FIG. 4. To facilitate the wedging of the bars 46 between the slabs 18, they are desirably shaped like a shollow S or have their ends slightly curved or rounded. The bars 46 shown in FIG. 3 are S-shaped, and can be readily wedged into place by rotation in a counter-clockwise direction.

Because the bars 46 remain in the hot top and are melted or otherwise remain in the steel, the bars are preferably formed of a low carbon steel material which will not adversely affect the killed steel being cast.

In order to prevent the buoyant force of the metal from lifting the slabs, wooden wedges 5()` are driven at each slab corner between the slab and the end wall of the mold (FIG. l). Further support for the heat producing slabs 18 is provided by the use of additional cross rods 52 which are like the previously inserted rods 44. These additional rods may be inserted through corresponding ones of the remaining hooks 22 which project from the upper edge of the slabs. These additional cross rods 52 rest on the upper end of the ingot mold as shown in FIG. 1 and afford support for the slabs during the pouring of the metal.

A mold in condition for receiving molten metal, which is hot topped in accordance with the present invention, is shown in FIG. l. During the teeming of molten metal into the ingot mold, the pourer should slow up but need not stop when reaching the bottom of the slabs 18. After the hot top is filled, the top of the ingot is conventionally covered with a granular insulating or heat producing substance such as a Thermite substance or the materials described, for example, on page 516 of the above mentioned book The Making, Shaping, and Treating of Steel. This added substance reduces or eliminates radiation and loss of heat from the open top of `the mold. Additional heat producing material can be added when needed if necessary to keep the top of the ingot molten.

As the molten metal reaches the heat producing slabs 18 during the pour, the temperature of the metal ignites the exotherrnically reacting material 20. This material continues to burn after the pour is completed and adds a substantial amount of heat to the upper end of the mold. As the molten metal in the mold solidies, the hotter upper portion serves as a feeder head and thereby fills the pipe or cavity within the ingot.

In order to provide a sloping tapered shoulder on the ingot between the main body and the hot top portion thereof, a construction which is desirable when the ingot is to be used in certain rolling and forging operations, the lower edge 55 of each slab 18 (as shown in FIG. 4) is tapered downwardly and outwardly. Such a taper in the completed ingot facilitates rolling and reduces the amount of crop which must be taken from the ingot.

In accordance with another aspect of the present invention, ingots which are approximately square in cross section and smaller than the slab ingots discussed above can be hot topped in a similar manner. When these ingots are hot topped with only two opposed slabs or side boards of heat producing material, we have found that surprisingly economical results are obtained. The ingots produced are sound in that the hot top does an eflicient job of feeding molten metal as the ingot shrinks.

When carrying out this aspect of the present invention, a generally square ingot is hot topped by lowering into the mouth of the mold a pair of slabs of heat producing material in much the same manner as described above. These slabs, constructed in the sa-me manner -as slabs 1S as shown in FIG. 2, are supported from the mouth of the ingot by cross rods as shown in FIG. 1, and are positioned against opposed side walls of the mold. The slabs are held in place by wooden wedges such as the wedges S0 shown in FIG. 1, and spreader rods such as the S- shaped rods 46 may be employed. We have found, however, that in the smaller size square lingot molds, the

wooden wedges serve to prevent the slabs from lioating on the molten metal and accomplish the purpose of holding the slabs apart and tightly against the mold walls. For example, a conventional ingot mold has a 23 inch x 24 inch cavity. Opposed heat producing slabs are suspended within the open mouth of the ingot cavity `by rods, such as the rods 44 through the loops 22, are

held up against opposite side Walls of the mold, and are wedged into place by wooden wedges driven between the ends of the slabs and the adjacent mold end walls.

As pointed out above, it is usually desirable to add a granular heat producing material onto the top of molten metal after it has been poured into the mold. This substance not only supplies additional heat to the mold but also serves as an insulating cover for the mold.

We claim as our invention:

1. In combination, a rectangular ingot mold having opposed side walls and relatively shorter end walls dening a mold cavity, and a pair of slabs of heat producing material suspended with-in the mold cavity and wedged in opposed relation against the mold side walls and between the opposed mold end walls which remain substantially bare, said slabs and said bare mold end walls defining a hot top cavity which is smaller in cross section than the mold cavity.

2. In combination, a rectangular ingot mold having opposed side walls and relatively shorter end walls delining a mold cavity, and a pair of slabs of refractory backed exothermically reacting material suspended within the mold cavity and wedged in opposed relation against the mold side walls and between the opposed mold end walls which remain substantially bare, said slabs and said bare mold end walls defining a hot top cavity which is smaller in cross section than the mold cavity.

3. In combination, a rectangular ingot mold having side walls and relatively shorter end walls defining a mold cavity, a pair of slabs of heat producing material suspended within the mold cavity and adjacent two opposed side walls only of the mold, and means wedging said slabs in position against said two side Walls and between the adjacent opposed end walls, thereby leaving the latter walls substantially bare, said slabs and said bare mold end walls defining a hot top cavity which is smaller in cross section than the mold cavity.

4. In combination, a slab ingot mold having vertical spaced side Walls and adjacent shorter end walls, a pair of opposed slabs of heat producing material lining only an upper portion of said side Walls and extending between said end walls which remain substantially bare, means supported on the upper end of said mold walls suspending said slabs within the mold, means holding said slabs in spaced apart relation and tightly against said mold side walls, and wedge means wedged between said end walls and said slabs f0.1` preventing said slabs from being raised out of the mold when molten metal is teemed therein, said slabs and said bare mold end walls defining a hot top cavity which is smaller in cross section than the mold cavity.

`5. In combination, an ingot mold for casting metal having vertical spaced side and end walls, opposed slabs of heat producing material lining only an upper portion of said side walls and extending between said end walls which remain substantially bare, said slabs comprising a layer of refractory heat insulating material and a layer of exothermically reacting material, and non-heat producing means holding said slabs in spaced apart relation and tightly against said side walls, thereby defining with said end walls a feeder head space, said holding means including a rod wedged between opposed surfaces of exothermically reacting material of said slabs.

6. In combination, a slab ingot mold having vertical spaced side walls and adjacent shorter end walls, opposed slabs of heat producing material lining only an upper portion of said side walls and extending between said end walls which remain substantially bare, said slabs comprising a layer of refractory heat insulating material having a recess defined in one surface thereof and a layer of exothermically reacting material in said recess, means vertically supporting said slabs within said mold, and means holding said slabs in spaced apart relation and tightly against said walls, said slabs defining with said end walls a feeder head space, said holding means including a non-heat producing means wedged between opposed surfaces of exothermically reacting material of said slabs and wedge means wedged between said end walls and the refractory edges of said slabs for preventing said slabs from being raised out of the mold when molten metal is teemed therein.

7. An ingot mold having an open end mold cavity for casting metal ingots, means for increasing ingot yields comprising, a pair of substantially exothermic side boards secured to said ingot mold along opposed inner surfaces of the upper portion of the mold cavity and on opposite sides of the pouring area of the mold, and bare surface areas on the inner surface of the mold between said side boards.

8. In combination, a rectangular ingot mold having vertical spaced side and end walls, a pair of opposed slabs of heat producing material lining only an upper portion of said side walls and extending between the end walls which remain substantially bare, means supported on the upper end of the mold for suspending said slabs in the mold, and means holding said slabs in spaced apart relation and tightly against said mold side walls, said slabs and said bare mold end walls defining a hot top cavity which is smaller in cross section than the mold cavity.

9. An ingot mold having an open end mold cavity for casting metal ingots, means for increasing ingot yields comprising, a pair of substantially exothermic side boards positioned within said ingot mold along opposed inner surfaces of the upper portion of the mold cavity and on opposite sides of the pouring area of the mold, and bare surface areas on the inner surface of the mold between said side boards.

10. In an ingot mold having an upwardly opened mold cavity -for casting metal ingots, a pair of exothermic side members positionably retained in the mold on opposite sides of the feed zone of said mold cavity, each of said members engaging a separate side board having a surface which engages and complements the inner surface of the mold cavity, and bare surface areas -on the inner surface of the mold between said side boards.

11. The ingot mold of claim 7 wherein Vsaid mold cavity is for casting big-end-down ingots,

12. The ingot mold of claim 7 wherein the upper portion of said mold cavity is defined by side Walls and relatively shorter end walls, the exothermic side boards being secured along said side walls. 13. An ingot mold having an open end mold cavity for casting metal ingots, means for increasing ingot yields comprising, a pair of substantially exothermic sideboards secured to said ingot mold along opposed inner surfaces of the upper portion of the -mold cavity and on opposite sides of the pouring area of the mold, bare surface areas on the inner surface of the mold between said sideboards, and a granular material selected from the group consisting of insulating substances and heat producing substances in said mold cavity on the top of said metal ingot to reduce loss of heat from the top of the mold.

14. An ingot mold having an open end mold cavity for casting big-end-down metal ingots, said mold cavity being defined by side walls and `relatively shorter end walls, means for increasing ingot yields comprising, a pair of substantially exothermic sideboards secured to said ingot mold along opposed inner surfaces of the upper portion of said side walls and on opposite sides of References Cited UNITED STATES PATENTS 2/ 1960 Edmonds et al. 249-201X 12/1954 Simpson 287-58X FOREIGN PATENTS 10/1904 France.

1914 Great Britain.

OTHER REFERENCES The Iron Age (Publication) Sept. 12, 1957, p. 123 lo relied upon, 22-147A.

J. SPENCER OVERHOLSER, Primary Examiner.

R. D. BALDWIN, Assistant Examiner.

Marburg 249-198 Marburg 249-197 Marburg.

NouVeaW 164-159 15 Vallak 249-197 249-200 U.S. Cl. X.R.

Claims (1)

1. 7. AN INGOT MOLD HAVING AN OPEN END MOLD CAVITY FOR CASTING METAL INGOTS, MEANS FOR INCREASING INGOT YIELDS COMPRISING, A PAIR OF SUBSTANTIALLY EXOTHERMIC SIDE BOARDS SECURED TO SAID INGOT MOLD ALONG OPPOSED INNER SURFACES OF THE UPPER PORTION OF THE MOLD CAVITY AND ON OPPOSITE SIDES OF THE POURING AREA OF THE MOLD, AND BARE SURFACE AREAS ON THE INNER SURFACE OF THE MOLD BETWEEN SAID SIDE BOARDS.

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