US3026585A

US3026585A - Sectional hot top

Info

Publication number: US3026585A
Application number: US847599A
Authority: US
Inventors: Marburg Edgar
Original assignee: United States Steel Corp
Current assignee: United States Steel Corp
Priority date: 1959-10-20
Filing date: 1959-10-20
Publication date: 1962-03-27
Anticipated expiration: 1979-03-27

Description

March 27, 1962 E. MARBURG SECTIONAL HOT TOP Filed Oct. 20, 1959 4 Sheets-Sheet 1 vINVENTOR. 0644 M MMM JWORNEY E. MARBURG SECTIONAL HOT TOP March 27, 1962 4 Sheets-Sheet 2 Filed Oct. 20, 1959 March 27, 1962 E. MARBURG 3,026,585

SECTIONAL -HOT TOP Q i l l l N Qi n N "IR INVENToR. W 20% ma@ 445026 N BY L* @mM/fw JNO/@yi Y March 27, 1962 E. MARBURG sEcTIoNAL HOT 'rop 4 Sheets-Sheet 4 Filed 001;. 20, 1959 w @uw 3,026,585 SECTIONAL HUT TOP Edgar Marburg, Pittsburgh, Pa., assignor to United States Steel Corporation, a corporation of New Jersey Filed Oct. 20, 1959, Ser. No. 847,599 Claims. (Ci. 22--147) This invention relates to a sectional hot top and more particularly to such a hot topi for use in a big-end-down ingot mold of large size such as 22 x 35 inches. Hot tops most commonly used for casting steel ingots are the one-piece variety. However, they have deiinite disadvantages, one of which is that they cannot closely iit the walls of the ingot mold since the tolerance allowed in such molds is such that the hot top must be designed to clear scrap that may adhere to the top of a mold of the minimum opening for a given size of ingot. The molds will generally be larger than this size. Because of the disadvantages of a one-piece hot top sectional hot tops have been produced and have had limited use. However, the sectional hot tops of which I have knowledge have proved unsatisfactory for various reasons. They may be difficult to manufacture and/or install, they may be weak structurally, they may not conform suiciently close to the mold wall to prevent metal from getting therebetween, the vertical joints between the slabs of the hot top may not Vbe sufficiently tight to prevent metal leakage, the slabs of the hot top may not always be at the same level when assembled in oversized molds, so that the volume of the sinkhead will not contain adequate metal to insure a sound ingot, and the shape of the opening formed by the hot top may not be the best for the most eiieient utilization of the metal in the sinkhead. With all of the hot tops of which I have knowledge the ingot weight will vary when the mold dimensions vary from those specified.

It is therefore an object of my invention to provide a sectional hot top with good structural strength which will closely contact all four walls of the ingot mold.

Another object is to provide such a hot top which is readily installed in an ingot mold.

Still another object is to provide such a hot top which will eliminate or greatly reduce the iins on ingots and produce a sound ngot.

A further object is to provide such a hot top which will enable the ingots to be so cast that they will be of approximately the same weight even if the mold dimensions vary above those specified.

These and other objects will be more apparent after referring to the following specification and attached drawings, in which:

FIGURE l is a plan view of an assembled hot top;

FIGURE 2 is an elevation showing the hot top assembled in an ingot mold;

FIGURE 3 is a view taken on the line III-III of FIG- URE l;

FIGURE 4 is a view taken on thetline IV-IV of FIG- URE 1;

FIGURE 5 is a view taken on the line V-V of FIG- UREI;

FIGURE 6 is a view taken on the line VI--VI of FIG- URE 1;

`FIGURE 7 is an enlarged view of the lower portion of FIGURE 6 showing the relationship of the side and end slabs when inserted in a mold of smaller size (for example lt inch smaller) than the nominal standard;

FIGURE 8 is a view, similar to FIGURE 7, but with the slabs inserted in a mold of standard size;

FIGURE 9 is a view, similar to FIGURE 7, but with the slabsinserted in a mold of larger size (for'example 1A inchv larger) than the nominal standard; and

FIGURE l0 isv a view, similar to FIGURE 9, but with Patented Mar. 27, i962 the slabs inserted in a mold of still larger size (for ex ample 1/2 inch langer) than the nominal standard.

Referring more particularly to the drawings, reference numeral 2 indicates the top of a mold on which the hot top is positioned. The hot top consists of a pair of end slabs 4 and a pair of side slabs 6. Each of the end slabs includes a generally vertical portion 8 and a generally horizontal portion It)` extending outwardly from the bottom of portion 8. The outer face 12 of the portion It) is shaped to contact the mold wall with the bottom I4 thereof being tapered inwardly to provide for ease of entrance into the mold. The portion 8 has a generally vertical groove I6 in its inner face adjacent each end thereof. As shown in FIGURE 6 the bottom of the groove 1.6 extends downwardly from the top of the slab in a substantially vertical plane for the majority of its length. It then tapers outwardly at 18 toward the inner face of the slab. I have found that the length of the portion 18 should preferably be about six inches and its taper 1A; inch per inch. As shown in FIGURE 3 the sides of the groove I6 slope downwardly toward the adjacent end face 20. Each of the end faces 2h preferably has a short vertical portion 22 at its top and a portion 24 adjacent thereto which tapers downwardly toward the opposite face. A tapered portion 26 is provided at the bottom for ease of insertion into the mold. Above portion 26 there is a base portion 28 which is shaped to conform to the wall of the mold. A recessed portion 30 is provided between the

portions

24 and 28 to allow clearance for any small pieces of slag or metal that may adhere to the mold wall. As shown in FIG- URES l and 5 the outer face of each of the vertical portions 8 is provided with a pair of holes 32, for receiving steel back-up rods 34 which extend outwardly beyond the horizontal portion l0. The rods 34 may be embedded in the slab during its manufacture. A vertical slot 36 extends upwardly from the bottom of the slab 4 and terminates short of the top thereof. An opening 38 extends inwardly from the top of slot 36 to the inner face of the slab. An exothermic insert iti is provided in the slot 36 and opening 38. The exothermic insert eil may be precast, in which case the refractory of the slab is formed therearound, or it may be placed in the slot during or after formation of the slab in powdered form, and subsequently baked to hardness at 300 to 400 F. for one or two hours. If desired the exothermic material need only be inserted at the bottom of slot 36 and in the opening 38 with a corrugated cardboard or other combustible ller preferably being provided in the slot 36 between the exothermic material. The slab is preferably made of sand with a resin binder. In some instances the exothermic material may be omitted and the slab made solid or with no exothermic material in the slot 36, in which case corrugated cardboard might be provided in slot 36. Vent holes 42 extend outwardly from the slot 36 to the outside face of the slab both to provide air for combustion and to allow escape of gases from the exothermic material. Each of the -side slabs 6 is preferably thicker at its ends tf-t than at the middle portion as shown with its ends` 44 being adapted to be received in the corresponding groove 16 in the end slabs. As shown in FIGURE 6 each end face of slab 6 extends downwardly at 46 for the majority of its height and tapers slightly (1m inch) inwardly toward the opposite end face. Bottom 48 of the end face extends at a greater taper (1/s inch per inch) toward the opposite lend face. The portion 48 has the same taper as portion V18 and is of less length.

hot top illustrated this width will be 16% inches, the same as the width between end pieces, to provide maximum etliciency of shape. Each of the slabs 6 is provided with a vertical slot '50, opening 52, exothermic insert 54 and vent holes 56 constructed in the same manner as

corresponding parts

36, 38, 40 and 42 of the end slabs.

Notches

58 and 60 may be provided in the middle of the top of slabs 4 and 6, respectively, to aid in assembling the slabs of the hot top in an apparatus for installing the hot top in the mold by crane.

in assembling the hot top in a mold the four slabs are arranged with the ends 44 of the side slabs 6 in the grooves 16 of the end slabs 4, but with the top of the side slabs some distance (about 6 inches) above the top of the end slabs. When so positioned the slabs are lowered into the ingot mold 2 until the tapered surfaces 24 of the end slabs 4 ibecome tightly wedged between opposide sides of the mold wall. As the end slabs 4 move downwardly to this position the rods 34 will be lowered inside the mold in contact with the mold wall and will bend slightly, but will back up the slabs 4 to resist the outward pressure of the liquid metal in the hot top. The side slabs 6 are then forced downwardly in the slots 16. As this occurs the taper in the sides of the grooves 16 directs the bottom of the side slabs 6 outward to near contact with the mold Wall. As may be seen in FIGURE 3 clearance is provided between the outside face of the side slab and the upper portion of the mold wall for any dirt on the mold wall near the top thereof. As shown in FIGURE 6 the matching tapers 48 and 18 force the bottoms of the end slabs outwardly into contact with the mold wall. lf the mold is undersize, for example, 1A of an inch, the end slab will tighten when the top of portion 48 is at or near the top of portion 18 as shown in FIGURE 7. When the mold is oversize, for example, it inch, the end slab will tighten when the bottom of the slabs are at the same height as shown in FIGURE 9. When the mold is at the exact specified dimensions the bottom of the portion 48 will be midway between the rst two positions as shown in FIGURE 8. When the mold is still further oversize (for example 1/2 inch) the bottom of the side slabs will drop below the bottom of the end slabs as shown in FIGURE 10. The close fit of the pieces with the mold walls prevents metal tins on ingots. The taper of portion 46 provides for reduction of the overall length of the assembled hot top for ease of insertion in the mold and also enables insertion in undersize molds. The mold and hot top are now ready for pouring the molten metal into the mold. It will be seen that the tapered portion 24 provides means for compensating for variation in the width of the mold opening. Thus the Wider the mold the further the slabs 4 go down into the mold. While this cuts down the height of usable metal in the ingot the total volume of usable metal will be approximately the same because the horizontal section is greater. This is a deiinite advantage since it is desirable to have the Volume of metal in the ingot constant. As the metal is poured into the mold the exposed faces of the exothermic material near the top are ignited by the heat from the pouring stream. The exothermic material in the bottom of the slot will be ignited when the liquid metal level approaches it. The material burns at about the rate of 1 inch per minute from each end to produce a temperature of 3000 to 3500u F. which rapidly heats both the inside and outside sand walls. Since the sinkhead metal is not directly in contact with the exothermic material except for small portions thereofV the metal will not be contaminated therewith. The inner sand walls `are made of such thickness that a metal shell of sufficient thickness will solidify to enable the ingot to be lifted by its sinkhead. Once the shell has solidied the inner walls are extremely hot and the temperature gradient across them is very low so that it eiectively restricts heat flow outwardly from the sinkhead. The

resin binder in the sand will volatilize from the heat of the poured metal so that the sand disintegrates readily about an hour after pouring and the stripped ingots are clean and substantially free from refractory contaminants.

While one embodiment of my invention has been shown and described, it will `be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. A sectional hot top for a generally rectangular mold comprising a first pair of slabs one located on each of two opposite sides of the mold, a second pair of slabs one located on each of the other sides of the mold, each of the first pair of slabs including a generally vertical portion, the generally vertical portion having a generally vertical groove in its inner face adjacent each end thereof, each of said grooves having a bottom and two sides, the bottom of each groove extending downwardly from the top of the slab in a substantially vertical plane for the majority of its length and then tapering toward the said inner face, the sides of each groove sloping downwardly toward the adjacent end face of its slab, the ends of each of said second pair of slabs being adapted to be received in the corresponding vertical groove of the first pair of slabs, the end face of each of said second pair of slabs extending downwardly for the majority of its length and then tapering toward its opposite end face, the last named tapered portion having the same slope as the tapered portion of the bottom of the groove in the associated rrst pair of slabs but of less length than the tapered portion of the bottom of the groove whereby the hot top can be inserted in oversize and undersize molds.

2. A sectional hot top according to claim 1 in which each of said slabs has a generally vertical slot extending from the bottom thereof upwardly less than the full height thereof and an inwardly extending opening from the top of said slot to the inner face of the slab, and exothermic material in said slot and opening.

3. A sectional hot top for a generally rectangular mold comprising a trst pair of slabs one located on each of two opposite sides of the mold, a second pair of slabs one located on each of the other sides of the mold, each of the trst pair of slabs including a generally vertical portion, the generally Vertical portion having a generally vertical groove in its inner face adjacent each end thereof, each of said grooves having a bottom and two sides the bottom of each groove extending downwardly from the top of the slab in a substantially vertical plane for the majority of its length and then tapering toward the said inner face, each of the end faces of said rst pair of slabs having a portion adjacent its bottom adapted to contact the mold wall, a portion adjacent its top tapering downwardly toward the opposite end face and a recessed portion between the top and bottom portions, the sides of each groove sloping downwardly toward the adjacent end face of its slab, the ends of each of said second pair of slabs being adapted to be received in the corresponding vertical groove of the rst pair of slabs, the end face of each of said second pair of slabs extending downwardly for the majority of its length and then tapering toward its opposite end face, the last named tapered portion having the same slope as the tapered portion of the bottom of the groove in the associated rst pair of slabs but of less length than the tapered portion of the bottom of the groove whereby the hot top can be inserted in oversize and undersize molds.

4. A sectional hot top for a generally rectangular mold comprising a first pair of slabs one located on each of two opposite sides of the mold, a second pair of slabs one located on each of the other sides of the mold, each of the first pair of slabs including a generally vertical portion and a generally horizontal portion extending outwardly from the bottom of the generally vertical portion, the generally vertical portion having a generally vertical groove in its inner face -adjacent each end thereof, each of said grooves having a bottom and two sides, the bottom of each groove extending downwardly from the top of the slab in a substantially vertical plane for the majority of its length and then tapering toward the said inner face, the sides of said grooves sloping downwardly toward the adjacent end face of its slab, the ends of each of said second pair of slabs being adapted to be received in the corresponding vertical groove of the iirst pair of slabs, the end face of each of said second pair of slabs extending downwardly for the majority of its length and then tapering toward its opposite end face, the last named tapered portion having the same slope as the tapered portion of the bottom of the groove in the associated rst pair of slabs but of less length than the tapered portion of the bottom of the groove whereby the hot top can be inserted in oversize and undersize molds.

5. A sectional hot top for a generally rectangular mold comprising a rst pairof slabs one located on each of two opposite sides of the mold, a second pair of slabs one located on each of the other Sides of the mold, each of the iirst pair of slabs including a generally vertical portion and -a generally horizontal portion extending outwardly from the bottom of the generally vertical portion, the generally vertical portion having a generally vertical groove in its inner face adjacent each end thereof, each of said grooves having a bottom and two sides, the bottom of each groove extending downwardly from the top of the slab in -a substantially vertical plane for the majority of its length and then tapering toward the said inner face, the sides of said grooves sloping downwardly toward the adjacent end face of its associated slab, each of said end faces having a portion adjacent its bottom adapted to contact the mold wall, a portion adjacent its top tapering downwardly toward the opposite end face and a recessed portion between the top and bottom portions, the outer face of said vertical portion having a plurality of holes therein above the said horizontal portion, rods in at least part of said holes extending outwardly from said holes beyond the said horizontal portion, the ends of each of said second pair of slabs being adapted to be received in the corresponding vertical groove of the first pair of slabs, the end face of each of said second pair of slabs extending downwardly and slightly toward the opposite end face for the majority of its length and then at a greater taper toward its opposite end face, the last named tapered portion having the same slope as the tapered portion of the bottom of the groove in the associated ''rst pair of slabs but of less length than the tapered portion of the bottom of the groove whereby the hot top can be inserted in oversize and undersize molds.

References Cited in the file of this patent UNITED STATES PATENTS 2,049,980 Turner Aug. 4, 1936 2,159,374 Estep May 23, 1939 2,433,775 Marburg Dec. 30, 1947 2,782,478 i Marburg Feb. 26, 1957 2,900,685 Marburg Aug. 25, 1959 FOREIGN PATENTS 1,112,520 France Nov. 16, 1955 1,112,966 France 'Nov. 23, 1955