US3097405A - Extruded ribbon of fire clay - Google Patents

Description

July 16, 1963 w. B. YERRICK 3,097,405

. EXTRUDED RIBBON OF FIRE CLAY Filed Nov. 22, 1960 Fig.2.

United States Patent 3,097,405 EXTRUDED RIBBON OF FIRE CLAY William B. Yerrick, Oakmont, Pa., assignor to Kittanning Brick Company, Reesdale, Pa., a corporation of Pennsylvania Filed Nov. 22, 1960, Ser. No. 70,959 8 Claims. (Cl. 22-147) This invention relates to improvements in the teeming of metal ingots and relates in particular to an improved method of efiecting a seal between ingot molds and hottop molds during pouring or teeming of steel ingots.

In the manufacture of wrought metal products and particularly wrought steel, it is customary to pour or teem molten metal from a ladle into ingot molds which are thick-walled iron castings of widely varying shapes and sizes. The metal or steel freezes or solidifies in these molds to form ingots which are subsequently stripped or removed from the molds and are bloomed or hot rolled and otherwise mechanically deformed to form wrought metal products. When molten metal such as molten steel solidifies or freezes, it is known to contract and lose some of the dimensional volume it occupies while in the liquid state. Since such freezing or solidification is not instantaneous, but occurs over a period of time and the ingot does not contract uniformly, but generally solidifies trom the bottom up and from the outside in so that any loss of dimension by the bottom of the ingot is compensated for immediately by the still molten metal above flowing downwardly to fill any void. At the top of the ingot, however, where there is no compensating molten metal to fill the void, there occurs what is known as pipe which is a cone-shaped cavity which forms in the top portion of the ingot during the solidification of the metal. The walls of such pipe generally oxidize and will not weld during subsequent rolling. Consequently, a major portion of the ingot must be cropped or removed and productivity or yield associated with the quantity of metal poured is greatly diminished, particularly where big end up molds which have a larger casting cavity at the top than the bottom, are employed. The undesirable ellects of pipe are generally minimized by employing what is known as a hot-top on top of the ingot. In this practice, a mold of smaller inside dimensional area is positioned above the ingot mold so that after teeming there is a rel-atively small reservoir of molten metal above the ingot mold and upon freezing and contraction of the ingot, molten met-a1 may flow from the hot-top mold to replenish loss of volume in the ingot mold and avoid the formation of pipe in the ingot proper. The hot-top itself is that smaller volume of metal remaining in the hot-top mold after freezing which exhibits considerable pipe, but which may be cropped from the ingot proper with very little loss of metal or reduction in yield. Hot-top molds vary in design and method of seating above the ingot mold, however, a common practice is to employ a hot-top mold that will seat directly onto the top surface of the ingot mold. Since both molds are generally made from metal castings, a sealing material must be employed to prevent the molten steel from penetrating from between the molds. Prior known sealing materials include what is known in the trade as asbestos rope, however, such rope is relatively expensive and is not entirely satisfactory in preventing the penetration of the molten metal. Such asbestos rope is not readily compressible and does not flow into the imperfections and warpage norm-ally found on both the top surface of the ingot mold and the bottom of the hot-top mold so that some steel usually penetrates between the molds during teeming when asbestos rope is employed. Prior attempts to employ cements or clay as a sealing material have been relatively unsuccessful because it is difficult to trowel on such a material evenly so that the molten steel 3,097,405. Patented July 16, 1963 will not penetrate between the molds. Additionally, it is necessary to add considerable water to a given clay mixture to provide the plasticity required to enable one to trowel it on. It is important to minimize the water content, since high water content clay mixture tend to slump and shrink when dried, which causes cracks and voids to occur in the seal. Where high water content clays are employed, some residual water remains even after the clay has been purposely dried by heating. Such residual water is known to boil during teeming and is known to cause excessive oxygen pick-up by the rising molten metal which, in turn, causes numerous oxide inclusions to occur in the steel. Also, high water content troweled-on clays tend to crumble when dried prior to teeming. Uneven applications of fire clay, resulting from troweling on such materials or cracking caused by excessive Water content, not only result in metal penetration between the molds but, also, cause dirty steel, which is a term applied to a steel which contains numerous large non-metallic inclusions (in this case, clay which has fallen into the mold cavity during or prior to teeming).

A similar problem also exists where a big end down ingot mold is employed. A hot-top is not generally used where this type of teeming is utilized, since the ingot freezes from the top down; however, a seal similar to that employed between a hot-top mold and an ingot mold must be effected between the ingot mold and the stool upon which it sits to prevent the molten metal from flowing between these two members during teeming.

It has now been found that by employing the extruded unfired fire clay rope or ribbon of the present invention between a hot-top mold and an ingot mold, or between an ingot mold and a stool, a strong and continuous seal may be effected that may be readily dried, is simple to apply, and which does not slump or shrink during teeming.

It is,.accordingly, the object of the present invention to provide a method whereby fire clay may be employed to effect a seal between an ingot mold and a hot-top mold during teeming that will not slump, shrink, crack or leave voids, but which will form a strong uniform and continuous seal.

It is a further object of the present invention to provide a method whereby extruded fire clay may be employed to effect a seal between any mold and any second member where such a seal is required to prevent molten metal from penetrating from the casting cavity during teeming.

It is also an object of the present invention to provide fire clay in a form that will enable one to place it about the top edge or flange of an ingot mold with greater ease and economy of application than by troweliug, so that when the hot-top mold is set on top of the ingot mold, it will form a uniform clay seal therebetween that, after drying and upon teeming, will form a uniform and effective seal between said molds.

Other objects and advantageous features will be obvious from the following specification and drawings where- 1n:

FIGURE 1 is a view in elevation of an extruded fire clay rope which is a preferred embodiment of the present invention;

FIG. 2 is a cross-sectional view of the extruded rope of FIG. 1 shown as seated on a segment of ingot mold wall;

FIG. 3 is a partial cross-sectional view showing the juncture of one Wall of a hot-top mold seated on a portion of one wall of an ingot mold; and

FIG. 4 is a cross-sectional view of a fire clay rope that constitutes another embodiment of the present invention.

In general, the present invention relates to an extruded fire clay rope or ribbon of low water content and relates in particular to such a rope or ribbon that is formed into a substantially oval shape, at least one elongated side of said ribbon having an indentation therein. The present invention also relates to the method of teeming ingots wherein the aforementioned fire clay ribbon is seated on the top surface of an ingot mold so as to enurely encompass the ingot mold casting cavity, a hot-top mold is seated on the top of said ingot mold and fire clay rope so that the rope deforms and flows under the weight of the hot-top mold to form a uniform. seal between said molds, heat is applied to the said fire clay rope or ribbon to drive off substantially all the moisture in the clay so that the fire clay will efiect a uniform seal between the molds that will prevent the molten metal from penetrating between the molds during teeming.

In making extrusions, such as are employed in the method of the present invention, various types of clay and other materials are brought together in order to attain the most desirable plastic properties that will enable the material to be extruded and yet retain sufiicient green strength or the ability to retain its shape after being dried. The fire clay rope of the present invention is manufactured from natural occurring earthy clays re sulting from the decomposition of rocks, chiefly feldspathic and containing hydrated alumina-silicates. Many types of clay are suitable for the manufacture of this product, including plastic surface clays, plastic shales and most fire clays. For the purposes of the present invention, all these materials are referred to as fire clays. The preferred materials are the more plastic fire clays of the siliceous, kaolinitic or aluminous type with a minimum pyrometric cone equivalent of Cone 16 (A.S.T.M. designation for refractories specification C 2456). Such mixtures and blends of clays preferably will fall within the following calculated approximate chemical analyses after ignition: 1

Percent by weight 'z 4040 A1 20-50 F6203 .5-5 CaO .5-5 MgO .0-5 Ti0 .0-5 Alkalies .5-5

The term, alkalies, as applied to the above analyses, includes any and all of the naturally occurring alkali or alkaline earth metal compounds found in clay deposits. In the gnited state, such materials are generally regarded as the oxides of sodium and potassium since these materials generally account for nearly all of the caustic materials present. It is common practice in calculated analyses to regard this range as the M120 and or K20 content.

Plasticity is that property which enables a clay to be distorted without rupture and to retain this distorted shape after the force has been removed. The plasticity, strength, workability and shrinkage of a clay is greatly affected by the size and shape of the clay particles. Therefore, the clay to be used must be carefully ground and. screened to develop a particle size range which will develop good plasticity and will dry with a minimum amount of shrinkage or cracking. The particle size range is as follows:

Percent Tyler standard mesh No. 8 to 28 inclusive 5-50 Tyler standard mesh No. 28 to 65 inclusive 5-40 Tyler standard mesh No. 65 to 100 inclusive 10 30 Tyler standard mesh N0. 100 to micron size 5-20 Heaiced to about 1000" C. to drive off water and volatile.

materia The water serves to develop plasticity while the binder aids plasticity, improves the extrusion characteristics and serves to develop additional strength of the material when it dries. The water content is critical for a given clay mix and must be carefully controlled to insure good extrusion, satisfactory handling characteristics, and proper plasticity.

The tempered clay mixture is then fed to a commercial extrusion machine which first shreds the material into small particles. These particles subsequently pass into a vacuum chamber and are then reconsolidated by an auger which forces the plastic clay mix into a mass and extrudes it through a suitable die.

The extruded clay rope will have a water content of from about 55-20%, by weight, and when placed on the top of an ingot mold and a hot-top mold is seated on top of the rope, the fire clay rope will deform sufficiently to fill all voids and imperfections occurring in the adjacent surfaces of both molds, but at the same time, will support the hot-top mold even though the mold may weigh up to a couple thousand pounds, so that the two molds will not come together and cause the clay to flow from between the molds, but the hot-top mold is entirely supported by the clay rope. The rope must, of course, be of such a length, and be so positioned, as to extend entirely around the casting cavity of the ingot mold and as to contact uniformly the bottom surface of the hot-top mold when it is seated on the ingot mold.

Although the water content of the extruded fire clay depends on the mechanical and physical properties of the specific mixture being employed so that the water content may vary from 8% to 20%, by weight, from 5% to 10% less water is needed for the extruded rope than for a comparable mix prepared for application with a trowel and, consequently, boiling is minimized. For example, a clay mixture which will require l7% water to trowel, may require only about 10% water to extrude. The preferred fire clay rope of the present invention will contain from 10% to 15%, by weight, water, which is less than that required to trowel on such mixtures.

Although clay rope of rectangular, square and round cross-sectional shapes have been successfully employed; the preferred shape is the substantially indented oval shape, such as is shown by FIG. 2 of the drawings. A rectangular-shaped rope does not readily flow or give, but instead tends to retain its extruded shape when dried, thus increasing the possibility of metal penetration during teeming in areas-where the molds are slightly warped. Round shapes also may fail to flow suificiently, and when dried, may permit metal penetration.

As shown by the drawings, clay rope 11 is extruded in the indented oval shape shown by FIGS. 1 and '2, however, when seated as shown in FIGS. 2 and 3 on the upper surface 13 of the ingot mold 15 and a hot-top mold 17 is seated on the rope 11 as shown by FIG. 3, rope 11 will flow and bulge.

It is to be noted that the rope 11 flows and bulges as shown at 19', but still supports the hot-top mold 17 and does not permit it to contact the ingot mold 15. In this manner, all defects and warpage imperfections of both molds are filled and a uniformly continuous seal is effected. The preferred cross-sectional configuration may be that of a double circle such as shown by FIG. 4, or may be that of an oval shape with a single indentation such .as is shown by FIG. 2. Either of the elongated sides of the oval may be seated on the upper surface of the ingot mold to obtain optimum results.

The next step in the method of the present invention is to dry the clay. This has been accomplished effectively by applying the clay rope and positioning the hot-top mold while the ingot is hot, such heat coming from the preceding teeming, or the mold and/or the hotat-op mold may be specially heated prior to assembly. Also, the rope has been successfully dried by inserting a flaming torch into the casting cavity and/ or by playing such a flame around the outside surface of the molds. Any source of heat may be employed so long as it raises the temperature of the rope sufliciently to drive ofi the water content. A temperature of from 300 F. to 1000 F. is usually suiticient. It is to be noted that contrary to prior attempts to employ fire clay to effiect the seal, the extruded ribbon will not shrink materially during drying, does not crumble or leave voids, and the bulges such as shown at 19 in FIG. 3, do not fall or crumble into the mold during teeming so as to effect dirty steel.

Although the temperature of molten steel is substantially above that required for firing many types of fine clay to effect a vitreous mass, the time at such temperatures during ordinary teeming is insufficient to cause the clay to vitrify. As a result, when the molds are stripped from the ingot, the clay seal may be easily removed in that the dried clay will readily part from the metallic surfaces.

Although the ideal dimensions of the fire clay rope of the present invention depend on the dimensions of the ingot mold and hot-top mold being employed, it has been found that for most purposes, two to 1" circles overlapped, provide an ideal shaped rope that will afiiord the desired flow and bulging, while resisting complete collapse for most teeming operations. In any event, a rope dimension of less than /2 in width and A in height would not be desirable in that a smaller dimension than this could not fill the imperfections and =warpage spaces occurring between the surface of the molds.

In the use of asbestos rope, a shelf of molten metal be tween the ingot mold and the hot-top mold frequently forms during teeming. Such a shelf is caused and forms Where the asbestos rope does not extend to the inside edge of the ingot mold or, may be due to improper seating of the asbestos rope or movement of the rope While seating the hot-top mold. Such a shelf causes damage to the ingot in that when the freezing ingot contracts, its entire weight is placed on the aforementioned shelf. The resultant stress concentrations frequently causes cracking of the ingot commencing in the vicinity of the shelf.

It is seen by FIG. 3 of the present drawings that the flow of a rope of the preferred shape eifects a bulge such as shown at 19 that usually extends beyond the edge 21 of the ingot mold so that no shelf can be formed.

As has been mentioned above, in big end down ingot teeming, the big or greater diameter end of the ingot is seated on a stool or bottom member and a similar seal is required for between the ingot mold and the stool. 'Ihe fire clay rope of the present invention possesses all the advantages for this application as it does for sealing the area between the hot-top mold and ingot mold during teeming.

It should be noted that the fire clay rope and method of the present invention are equally applicable to all ingot molds regardless of their shape. For example, the fire clay rope may be laid along the top surface of octagonal, square or hexagonal-shaped molds, as well as round molds, since the clay rope may be bent or formed to conform to the shape of the ingot and hot-top molds.

It also is noted that the present fire clay rope may be slightly overlapped and joined and welded by hand to completely circumvent the casting cavity.

I claim:

1. In the method of teeming ingots wherein a hot-top mold is set on top of an ingot mold and molten metal is cast into the casting cavities of said. molds until the molten metal rises into the hottop mold, the improvement comprising, seating an extruded elongated rope of of undried and unfired fire clay continuously about the top surface of said ingot mold so as to completely circumvent said casting cavity, seating said hot-top mold on top of said ingot mold and fire clay rope so as to flow said extruded fire clay between said molds to form a uniform seal therebetween, drying said fire clay and teeming.

2. In the method of teeming ingots wherein a hot-top mold is set on top of an ingot mold and molten metal is cast into the casting cavities of said molds until the,

molten metal rises into the hot-top mold, the improvement of extruding an elongated rope of unfired and undried fire clay that contains from about 8% to 20%, by weight, water, into a substantially oval shape, at least one elongated side of which is formed with an indentation therein, seating said rope on the top surface of said ingot mold on at least one elongated side of said ovalshaped extruded fire clay rope so that said rope completely encompases the casting cavity of said ingot mold, seating said hot-top mold on top of said ingot mold and fire clay rope so as to flow said extruded fire clay between said molds to form a uniform seal therebetween, drying said fire clay and teeming.

3. In the method of teeming ingots wherein a hot-top mold is set on top of an ingot mold and molten metal is cast into the casting cavities of said molds until the molten metal rises into the hot-top mold, the improvement of extruding an elongated rope of unfired and rundried fire clay of the following dry weight chemical analysis after ignition:

Percent by Weight 40-70 20-40 Si0 A1203 F8203 .5-5 CaO .5-5 MgO Up to 5 TiO Up to 5 Alkalies .5-5

that contains from about 8% to 20%, by Weight, water, and seating said rope continuously about the top surface of said ingot mold so as to completely circumvent the casting cavity of said mold, seating said hot-top mold on top of said ingot mold and fire clay rope so as to flow said extruded fire clay between said molds, so as to form a uniform seal between said molds, drying said fire clay and teeming.

4. In the method of teeming ingots wherein a hot-top mold is set on top of an ingot mold and molten metal is cast into the casting cavities of said molds until the molten metal rises into the hot-top mold, the improvement of extruding an elongated rope of unfired and undried fire clay of the following dry weight chemical analysis after ignition:

stantially oval shape, at least one elongated side of which is formed With an indentation therein, seating said rope on the top surface of said ingot mold on at least one elongated side of said oval shaped extruded fire clay rope so that said rope completely encompases the casting cavity of said ingot mold, seating said bot-top mold on top of said ingot mold and fire clay rope so as to fiow said extruded fire clay between said molds to form a uniform seal therebetween, drying said fire clay and teeming.

5. In the method of teeming ingots wherein a hot top mold is set on top of an ingot mold and molten metal is cast into the casting cavities of said molds until the molten metal rises into the hot-top mold, the improvement comprising, extruding an elongated rope of unfired and un- 7 dried fire clay of the. following calculated chemical analyses after ignition:

Percent by weight Si 40-70 A1 0 20-40 F203 .5-5 CaO .5-5 M g0 Up to 5 TiO Up to 5 Alkalies .5-5 Water 8-20 Binder Up to 5 seating said rope continuously about the top surface of said ingot mold seating said hot-top mold on top of said ingot mold and fire clay rope so as to fiow said extruded fire clay between said molds and form a uniform seal therebetween, drying said fire clay and teeming.

6. In the method of teeming ingots wherein a hot-top mold is set on top of an ingot mold and molten metal is cast into the casting cavities of said molds until the molten metal rises into the hot-top mold, the improvement comprising, extruding an elongated rope of unfired and undried fires clay of the following calculated chemical analysis after ignition:

Percent by weight Si0 40-70 A1 0 20-40 F203 -5 5 CaO .5- 5 MgO Up to 5 TiO Up to 5 Alkalies .5- 5 Water 8-20 Binder Up to 5 At least one material selected from the group consisting of 12-20 mesh silica sand and 12-20 mesh grog 5-20 seating said rope continuously about the top surface of said ingot mold, seating said hot-top mold on top of said ingotmold and fire clay rope so as to flow said extruded.

fire clay between said molds and form a uniform seal therebetween, drying said fire clay and teeming.

7. In "a method of casting molten metal into a mold wherein a seal is effected between said mold and a stool to. prevent said molten metal from penetrating between said mold and said stool, the improvement comprising seating an extruded elongated rope of undried and unfired fire clay continuously about the top surface of said stool so as to completely encompasse the casting cavity of said mold when seated on said stool, seating said mold on said stool and fire clay rope so as to flow said extruded fire clay between said mold and stool to form a uniform seal therebetween, drying said fire clay and castmg.

8. In the method of casting molten metal into a mold wherein a seal is effected between said mold and a stool to prevent said molten metal from penetnating between said mold and said stool, the improvement of extruding an elongated rope of unfired and undried fire clay that contains from about 10% to 15%, by weight, water, into a substantially oval shape, at least one elongated side of which is formed with an indentation therein, seating,

said rope on the top surface of said stool on at least one elongated side of said oval-shaped extruded fire clay rope so that said rope completely encompasses the casting,

cavity of said mold when seated on said stool, seating said mold on said stool and fire clay rope so as to flow said extruded fire clay between said mold and stool to form a uniform seal therebetween, drying said fire clay and casting.

References Cited in the file of this patent UNITED STATES PATENTS 1,332,905 Lindemuth Mar. 9, 1920 2,049,981 'Iurner Aug. 4, 1936 2,099,342 Lemmerman Nov. 16, 1937 2,863,192 Kauffman Dec. 9, 1958

Claims (1)

1. IN THE METHOD OF TEEMING INGOTS WHEREIN A HOT-TOP MOLD IS SET ON TOP OF AN INGOT MOLD AND MOLTEN METAL IS CAST INTO THE CASTING CAVITIES OF SAID MOLDS UNTIL THE MOLTEN METAL RISES INTO THE HOT-TOP MOLD, THE IMPROVEMENT COMPRISING, SEATING AN EXTRUDED ELONGATED ROPE OF OF UNDRIED AND UNFIRED FIRE CLAY CONTINUOUSLY ABOUT THE TOP SURFACE OF SAID INGOT MOLD SO AS TO COMPLETELY CIRCUMVENT SAID CASTING CAVITY, SEATING SAID HOT-TOP MOLD ON TOP OF SAID INGOT MOLD AND FIRE CLAY ROPE SO AS TO FLOW SAID EXTRUDED FIRE CLAY BETWEEN SAID MOLDS TO FORM A UNIFORM SEAL THEREBETWEEN, DRYING SAID FIRE CLAY AND TEEMING.

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