US3421731A

US3421731A - Hot top maintaining system

Info

Publication number: US3421731A
Application number: US665081A
Authority: US
Inventors: William Henry Koch; George Rocher
Original assignee: METALLURGICAL EXOPRODUCTS CORP
Current assignee: METALLURGICAL EXOPRODUCTS CORP
Priority date: 1967-09-01
Filing date: 1967-09-01
Publication date: 1969-01-14
Anticipated expiration: 1986-01-14
Also published as: FR1578584A; GB1196998A; BE720029A; NL6812490A; LU56787A1; DE1758908B1; DE6604939U; JPS4947055Y1

Description

Jan. 14, 1969 w. H. KOCH ET AL HOT TOP MAINTAINING SYSTEM Sheet 1 of 2 Filed Sept. 1. 1967 clzep and H. Koo/2.

Jan. 14, 1969 w. H. KOCH ET AL HOT TOP MAINTAINING SYSTEM Sheet Filed Sept. 1, 1967 [MVP/1777055 gorge Roe/zen and g m H Koch.

United States Patent 3,421,731 HOT TOP MAINTAINING SYSTEM William Henry Koch, Trenton, Mich., and George Rocher,

Pittsburgh, Pa., assignors to Metallurgical Exoproducts Corporation, McKees Rocks, Pa.

Filed Sept. 1, 1967, Ser. No. 665,081

US. Cl. 249-197 7 Int. Cl. B22d 7/10 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a hot top for an ingot mold or the like and to means for fabricating, installing and maintaining preformed hot top members within the mold structure. More particularly, the invention pertains to a hot top construction for relatively large ingot molds and having preformed components which are not subject to floating.

Although, the hot top of the invention is applicable to ingot molds for other types of ingot material, the hot top is especially useful in the art of steelmaking and thus will be described mainly in his applicational background. Functionally, the hot top furnishes a source of heat and thermal insulation at the upper portions of the ingot mold structure. For this reason the hot top is usually fabricated from an exothermic insulating material. There are many forms of exothermic materials known to the industry. For the most part exothermic materials for the most include ferrous oxide and free aluminum which react at temperatures above 1000 F. to form aluminum oxide with release of considerable heat. These chemical reactions are of course well known and are readily initiated when the hot top is contacted by molten steel, the melting point of which is 2700 F.

As the ingot cools and hardens within the mold structure, the hot top is so positioned therewithin to apply considerable heat to the upper end of the ingot while the remainder of the ingot progressively cools and solidifies. Heating the hot top portion of the ingot is essential in order to maintain the steel in a molten condition at the top of the ingot. Thus, molten steel from the ingot top can flow inwardly and downwardly to fill the central cavity which tends to form within the ingot as a result of shrinkage during its solidification.

Although the hot top is expendable and must be renewed with each pour, it is extremely important to fit the hot top properly within the upper region of the mold structure. Maintaining a proper fit prevents the molten steel from rising between the hot top and the mold as the level of the steel rises within the mold structure. The presence of molten steel between the hot top components and the adjacent wall surfaces of the mold permits the hot top components to become freely contacted by the liquid steel whereupon the hot top components are able to float by virtue of Archimedes principle. If there is no liquid steel between the adjacent wall and the sideboards or similar components of the hot top there is no tendency to float.

It is customary to fabricate hot tops from easily molded 3,421,731 Patented Jan. 14, 1969 and handled components or sideboards of essentially flat or linear construction which conform to the generally rectangular ingot molds in use at the present time. The sideboards usually are molded about a reinforcing wire mesh and various types of hanger wires, or rods such as Z-bars, are molded within the sideboards. By means of such wires or rods the sideboards are suspended from the upper edges of the mold structure or from pipes or rods laid along the inside upper edges of the mold. With the sideboards thus suspended, a problem arises in maintaining the lower edges of the sideboards in close-fitting engagement with the adjacent inner mold surfaces to prevent the liquid steel or other molten material from rising therebetween.

In some applications, the tendency of the hot top to float can be prevented by utilizing a one-piece closely fitted hot top to prevent the molten steel from rising behind the hot top and the ingot mold wall. A one-piece closely fitting hot top, however, is impractical particularly in the case of the larger ingot molds, owing to the fragility of the exothermic or insulating material, the difiiculties of prefabricating and handling, manufacturing tolerances, and the likelihood of buckling when the continuous hot top is fitted within a mold which is hot from a previous pour.

Many proposals have been advanced for the purpose of preventing liquid steel from rising between the hot top and the adjacent mold surfaces. Such proposals involve additional structural components such as wiper strips which are attached to the hot top but which usually melt before the molten steel can rise above the lower inner surfaces of the sideboards and press the sideboards against the mold surfaces. Examples of such sealing means are disclosed by Charman et al., US. Patent No. 1,804,207 and Urmetz, U .S. Patent No. 2,300,077.

Other previously proposed hot tops involve complicated means for suspending or retaining hot top components in the top portion of the ingot mold. Such suspending or retaining means as typified by Nicholas, US. Patent No. 2,272,018, Gathmann et al., No. 1,501,655 and Marburg, No. 2,914,825, are not reliable for many applications and do not eliminate the possibility of floaters. Moreover, these prior hot tops involved complicated structural shapes which cannot be readily molded within the hot top sideboards by conventional techniques.

We overcome these disadvantages of the prior art by providing a unique hot top construction which can be assembled from prefabricated components of readily vari able sizes. Our novel hot top construction and our novel means of fabricating and installing the same positively prevents molten steel from rising behind and floating the hot top. Our hot top is quickly and easily installed by suspension of the hot top components from the upper edges of the mold structure. For this purpose simple hanger rods or wires are employed, which are readily molded within the sideboards when the latter are preformed. Quickly installed means are then used to maintain the sideboards tightly against the inner mold surfaces.

In a typical application our novel hot top structure includes a plurality of premolded or otherwise preformed sideboards which are suspended adjacent the inner wall surfaces of the ingot mold. Each of the sideboard members is provided with a pair of angularly disposed grooves formed on its inward face and adjacent its ends respectively. After the sideboards are installed, restraining means are inserted into a pair of such grooves adjacent each corner of the mold. The retaining means are positioned within the associated pair of grooves to apply a maximum retaining force adjacent the lower ends of the grooves for the purpose of forcefully engaging the lower edge of the sideboards with the mold structure. Means are associated with the restraining members or with the grooves or both for the purpose of maximizing the restraining forces adjacent the lower edges of the sideboards.

Although the restraining means can be made of steel and therefore melted when molten steel is poured, the restraining means are still able to hold the sideboards lightly in place as described above, until the level of the liquid steel rises above the downward edges of the sideboards, and whereupon the weight of the steel presses or restrains the sideboards tightly to the mold surfaces. When this occurs the sideboards, of course, likewise cannot be floated, as the pressure of liquid steel on the inward faces of the sideboards prevents the steel from rising behind the sideboards.

We accomplish these desirable results by providing a hot top for an ingot mold and the like, said hot top comprising a plurality of preformed elongated sideboards suspendable adjacent corresponding wall surfaces of said ingot mold, each of said sideboards having a pair of inclined grooves formed on the inward face thereof and disposed adjacent the ends thereof respectively, the inclination of each pair of adjacent grooves on respectively adjacent end portions of said sideboards having a downward convergency when said sideboards are so suspended, restraining means insertable into each pair of adjacent grooves and movable therealong to points of bearing contact with said sideboards adjacent the lower edges thereof to engage forcefully said edges with the adjacent surfaces of said mold when said sideboards are so suspended.

We also desirably provide a similar hot top wherein restraining means include a number of wedge plates, each of said plates being so shaped that insertion of said plates into respective pairs of said adjacent grooves and movement therealong causes increasing forces to be applied to the associated sideboards to press at least the lower edges of said sideboards into close fitting engagement with said mold.

We also desirably provide a similar hot top wherein each of said wedge plates is provided with opposed inclined edges, the inclination of said edges being slightly less than the inclination of said grooves so that said forces are concentrated adjacent the lower ends of said grooves and the lower edges of said sideboards.

We also desirably provide a similar hot top wherein said restraining means include a number of spring hooks of generally U- or V-shaped configuration, said hooks being so shaped that they are increasingly compressed as they are moved along said pairs of grooves, respectively.

We also desirably provide a similar hot top wherein a stop member is formed at the lower end of each of said grooves and adjacent the lower edge of the associated one of said sideboards to limit the downward movement of said spring hooks.

During the foregoing discussion, various objects, features and advantages of the invention have been set forth. These and other objects, features and advantages of the invention have been set forth. These and other objects, features and advantages of the invention together with structural details thereof will be elaborated upon during the forthcoming description of certain presently preferred embodiments of the invention and presently preferred methods of practicing the same.

In the accompanying drawings, I have shown certain presently preferred embodiments of the invention and have illustrated certain presently preferred methods of practicing the same, wherein:

FIGURE 1 is an isometric view illustrating the top portion of an ingot mold and showing one arrangement of our novel hot top positioned in the upper portion of the mold structure;

FIGURE 2 is an enlarged, partial, isometric view of the structure shown in FIGURE 1 and illustrating one arrangement of the sideboard restraining means;

FIGURE 3 is a similar view showing another arrangement of the sideboard restraining means; and

FIGURE 4 is a partial cross sectional view of the apparatus shown in FIGURE 3, as taken along reference line IV-IV thereof, including the plane of the restraining wedge 52.

Referring now to FIGURES l and 2 of the drawings the hot top 10 of our invention is arranged for insertion within the upper open end of a mold structure 12. Desirably, the hot top 10 is placed so that the upper edges thereof are depressed slightly below the adjacent upper edges of the mold structure 12 as denoted by dimensional arrow 14.

In an exemplary application the hot top 10 includes four generally linear and fiat sideboards 16 as better shown in FIGURE 1. Each of the sideboards 16 is prefabricated in accordance with conventional techniques, as by molding and sintering from a powdered or particulate insulating and exothermic material. For pouring steel ingots, the sideboards 16 desirably include an exothermic material containing ferrous oxide and metallic aluminum. Instead of sintering the exothermic material, the latter can be mixed with a pre-setting binder such as formaldehyde resins, which are conventionally used in foundries in connection with the so-called hot box process. When the exothermic material is contacted by the rising steel and reaches a temperature of about 1000 F. the following reaction takes place: 3FeO+2Al Al O +3Fe+A. This reaction evolves considerable heat and the material may reach a temperature of about 4000 F.

Each of the sideboards 16 is preferably molded about a wire reinforcing mesh 18 and one or more hanger wires 20 are partially imbedded in the sideboards 16 when molded. The hangers 20 can be bent about supporting pipes or rods 22 laid along the upper inner edges 24 of the mold structure to suspend the sideboards 16 therewithin. Alternatively, the sideboards 16 (as sideboards 16' in FIGURE 3) can be provided with a Z-bar 26 similarly imbedded in each end portion of the sideboards during the molding process, as better shown in FIGURE 3 of the drawings. The Z-bars 26 likewise suspend the sideboards 16' from the upper surface of the mold structure 12.

Referring again to FIGURES 1 and 2 of the drawings, each of the sideboards 16 is provided with an inclined groove 30 adjacent each of its ends 32. The grooves 30 are formed on the inward faces 33 of the sideboards 16. A pair of such grooves 30 are thus disposed at each corner of the mold structure as shown in FIGURE 1. The inclination of each pair of grooves 30 is such that they exhibit a downward convergency, as better seen from FIGURE 2. In this example, each of the grooves 30 is terminated short of the lower edge 34 of the associated sideboard 16 to form an integrally molded stop 36.

It will be seen from the description at this point that the sideboards 16 are suspended from the top edges of the mold 12 by means of hanger wires 20 (FIGURE 2) or Z-bars 26 (FIGURE 3). However, unless some means are provided for pressing those portions of the sideboards 16 adjacent their lower edges 34 into positive, close-fitting engagement with the adjacent inner surfaces of the mold structure 12, the sideboards 16 will float, when liquid steel or other molten ingot material rises between the sideboards 16 and the adjacent mold surfaces.

We eliminate such tendency to float by providing restraining means acting in cooperation with the grooves 30 for urging the lower edge portions 34 of the sideboards into close fitting engagement with the adjacent mold surfaces. One arrangement of such restraining means as shown in FIGURES 1 and 2, includes a spring hook 38 of inverted V- or U-shaped configuration insertable into each pair of adjacent grooves 30. The lower end portions 40 of the hook 38 are bent inwardly as shown in FIGURE 2 to provide smooth leg surfaces 42 for engaging each pair of the grooves 30. Desirably, the hooks 38 are fabricated from a spring steel wire which for 'a typical hot top application may be about A inch in diameter.

In the relaxed position of the hook 38, as denoted by its chain outline 44 in FIGURE 2, the lower ends 40 of the hooks can be readily inserted into the upper ends 46 of the grooves 30, i.e., at the widest separation between each pair of grooves 30. The hooks 38 are then forced downwardly to its solid outline position in FIGURE 2 until further downward movement is terminated by engagement of the hook surfaces 42 with the groove stops 36, respectively. The groove engaging leg surfaces 42 of the hook 38 are now adjacent the closest separation of the grooves 30 and are also closely adjacent the lower edges 34 of the associated sideboards 16. Thus, the resultant, maximum forces exerted by the hooks 38 at the sideboard grooves 30 is directed toward the sideboard lower edge portions 34 to cause these portions to forcefully engage the adjacent surfaces of the mold structure 12 and to restrain the sideboards against floating when the ingot is poured into the mold. Accordingly, it is impossible for liquid steel or other molten ingot material to rise behind the sideboards 16 and to float the sideboards.

When the ingot material is molten steel the spring hooks 38 will of course be melted when contacted thereby. However, at such times the spring hooks 38 have already servedtheir function as the then rising level of the liquid steel, as denoted by the reference line 48, is sufiiciently above the lower sideboard edges 34 so that the sideboards 16 continue to be pressed into engagement with the mold structure 12. With the arrangement as thus described the spring hooks 38 can be easily inserted into the grooves 30 from the top of the mold structure 12 and without prior bending and compressing and readily pushed downward either manually or by tapping with a hammer or mallet. As a result the camming action or inclined plane action of the grooves 30 performs the major proportion of the effort in compressing and mounting the spring hooks 38. The use of the stops 36 (although not essential to the invention, as the open-bottomed grooves 50 of FIGURE 3 can be employed instead) eliminates any possibility of operator error in properly locating the hooks 38 including their groove engaging portions 42.

Referring now to FIGURES 3 and 4 of the drawings, another modification of our novel hot top arrangement is disclosed therein. The hot top includes the aforementioned sideboards 16' provided with Z-bars 26. Each of the sideboards 16 are provided with a pair of grooves 50 adjacent their ends 32'. The inclination and location of the grooves 50 are similar to the grooves 30 of FIGURE 2 with the exception that the lower stops 36 of FIGURE 2 are omitted and the grooves 50 open onto the bottom edges 34' of the sideboards.

Cooperating with each pair of the grooves 50 is another form of our sideboard restraining means which include in this example a number of wedge plates 52, the configuration of which is better shown in FIGURE 4. The opposed and inclined sides 54 of each wedge plate 52 are shaped so that increasing force is exerted upon the sideboards including their lower edge portions as the wedge plates are moved downwardly along the grooves 50. Desirably, the inclined edges or sides 54 are provided with a slightly lesser angle of inclination relative to the inclination (FIGURE 4) of the associated grooves 50 to concentrate the forces exerted upon the sideboards 16' adjacent their lower edges 34. For example each groove 50 may have an inclination of 11 to the vertical as denoted by arrow 56 while each wedge side may have an inclination of 10 to 10 /2 as denoted by dimensional arrow 58. It will be understood of course that the aforesaid inclination angles are exemplary and that other angles of inclination may be employed as long as the angle of inclination of the grooves 50 is somewhat greater than that of the wedge plate 52.

The wedge members 52 are inserted from the top of the mold structure 12 until their inclined edges 54 bearingly engage the bottoms of the grooves 50, or until the difference in their inclined edge inclination, (when used) relative to the inclination of the grooves 50 causes the inclined edges 54 of the wedge plate 52 to bearingly engage only lower end areas 59 of the grooves 50, as better shown in FIGURE 4. Each wedge plate 52 is then pushed manually downward or lightly tapped in this direction by a hammer or a mallet until the resulting further downward movement of the wedge plates 52 impose the desired restraining forces upon the lower edge portions 34' of the sideboards 16'. To prevent gouging the lower portions of the grooves 50, the lower corners of the wedge plates 52 can be rounded off (not shown). Alternatively, the lower edge 60 of each wedge plate 52 desirably be made slightly shorter than the narrowest separation between the bottom surfaces of the grooves 50 at the lower ends 61 so that the lower edge 60 of each plate 52 projects downwardly of the sideboards 16, as also better shown in FIGURE 4.

As shown in FIGURES 2 and 3, at least the outward wall surfaces 62 or 62 of each pair of the

grooves

30 or 50 are disposed generally parallel to the plane of the associated hook 38 or wedge plate 52 when inserted therein to and in retaining the hook or plate within the

grooves

30 or 50, respectively.

From the foregoing it will be apparent that novel and efficient forms of hot tops have been disclosed herein. The hot top 10 or 10 or equivalents thereof result in the application of sufiicient restraining forces to the lower edge portions 34 or 34' of the sideboards 16 or 16' to prevent liquid steel or other molten ingot material from rising between the sideboards and the adjacent surfaces of the mold structure. In the case of molten steel, neither the spring hooks 38 nor the wedge plates 52 are melted to release the restraining forces until the molten steel has risen sufficiently so that its own Weight in turn restrains the sideboards 16 or 16' against the mold structure.

While we have shown presently preferred embodiments of the invention and have illustrated presently preferred methods of practicing the same, it is to be distinctly understood that the invention is not limited thereto but may be variously embodied and practiced within the scope of the following claims.

We claim:

1. A hot top for an ingot mold and the like, said hot top comprising a plurality of end adjacent preformed elongated sideboards, means for suspending said sideboards adjacent corresponding wall surfaces of said ingot mold, each of said sideboards having a pair of downwardly and outwardly inclined grooves formed on the inward face thereof and disposed near the ends thereof respectively, whereby the inclination of each pair of grooves on respectively adjacent end portions of said sideboards have a downward convergency, and means insertable into each of said pairs of adjacent grooves and movable therealong to points of bearing contact with said sideboards adjacent the lower edges thereof for restraining said sideboards flushly against said wall surfaces and for engaging forcefully at least portions of said sideboards adjacent said edges with said wall surfaces to prevent said sideboards from floating when said ingot is poured into said mold.

2. The combination according to claim 1 wherein said retraining and engaging means include a number of spring hooks of generally U- or V-shaped configuration, said hooks being so shaped that they are increasingly compressed as they are moved along said pairs of grooves, respectively.

3. The combination according to claim 1 wherein said restraining and engaging means include a number of wedge plates, each of said plates being so shaped that insertion of said plates into respective pairs of said adjacent grooves and movement therealong causes increasing forces to be applied to the associated sideboards to press at least the lower edges of said sideboards into close fitting engagement with said mold.

4. The combination according to claim 2 wherein a stop member is formed at the lower end of each of said grooves and adjacent the lower edge of the associated one of said sideboards to limit the downward movement of said spring hooks.

5. The combination according to claim 2 wherein the end portions of each of said spring hooks are bent inwardly to provide a smooth engagement with the bottoms of said grooves.

6. The combination according to claim 1 wherein the cross-sectional configuration of each pair of adjacent grooves are inclined generally toward one another to facilitate retention of said restraining and engaging means therebetween.

7. The combination according to claim 3 wherein each of said wedge plates are provided with opposed inclined edges, the inclination of said edges being slightly less than the inclination of said grooves so that said forces are concentrated adjacent the lower ends of said grooves and the lower edges of said sideboards.

References Cited UNITED STATES PATENTS WILLIAM J. STEPHENSON, Primary Examiner.

R. D. BALDWIN, Assistant Examiner.

US. Cl. X.R.