US3456690A

US3456690A - Composite sleeve for ladle stopper rods

Info

Publication number: US3456690A
Application number: US641538A
Authority: US
Inventors: Seth E Weed
Original assignee: Vesuvius Crucible Co
Current assignee: Vesuvius Crucible Co
Priority date: 1967-05-26
Filing date: 1967-05-26
Publication date: 1969-07-22
Anticipated expiration: 1986-07-22

Description

Juiy 22, 1969 s. E. WEED coMPosrTE SLEEVE Eon LADLE sToPPER nous original Filed March 12, 1965 Seth E Weed United States Patent O COMPOSITE SLEEVE FOR LADLE STOPPER RODS Seth E. Weed, Penn Hills Township, Pa., assignor to Vesuvius Crucible Company, Swissvale, Pa., a corporation of Pennsylvania 'Continuation of application Ser. No. 439,323, Mar. 12,

1965. This application May 26, 1967, Ser. No. 641,538 Int. Cl. C21b 7/12; F161 9/14, 57/00 U.S. Cl. 13S-140 6 Claims ABSTRACT F THE DISCLOSURE A sleeve for protecting a metal stopper rod comprising a refractory unitary hollow cylinder having an outer stratum and an inner stratum, the material of the outer stratum having a greater resistance to corrosion and erosion than the material of the inner stratum and the material of the inner stratum having a greater thermal insulating effect than the material of the outer stratum. The wall thickness of the inner stratum is substantially greater than, preferably at least double, the wall thickness of the outer stratum. The inner stratum may be of zirconia, bubble alumina or refractory clay, and the outer stratum may be of alumina, magnesia, a mixture of refractory clay and graphite, Zircon or spinel.

This application is a continuation of my copending application Ser. No. 439,323, filed Mar. 12, 1965, now abandoned.

This invention relates to a composite sleeve for ladle stopper rods. It relates more particularly to a sleeve affording both optimum corrosion and/or erosion resistance and optimum thermal insulation.

Metal stopper rods, normally made of steel, are used for operating ladle Stoppers of the type employed in bottom pour ladles which are used for receiving molten steel tapped from open hearth or other steel making furnaces and teeming the molten steel into ingot molds. The steel rod is disposed in the molten steel whose temperature may be of the order of 2900-2950 F. for a period 0f thirty to sixty minutes. The high temperature of the molten steel would soften or melt the rod if the rod were not insulated against such temperature. But the slag which is unavoidably formed in steel making and which is tapped from the steel making furnace along with the molten steel or which forms on the surface of the molten steel in the ladle may be highly corrosive and/ or erosive tending to deteriorate insulating material used to protect the steel rod from the heat of the molten steel.

The use of sleeves disposed about steel ladle stopper rods is universal. However, a sleeve made of material which is readily attacked by the corrosive or erosive slag does not give satisfactory results, and the same is true of a sleeve which does not afford adequate heat insulation to the rod.

I provide a sleeve for protecting a metal stopper rod which comprises a unitary hollow cylinder having an outer stratum of corrosionand/or erosion-resistant refractory material and an inner stratum of thermal insulating refractory material. My sleeve thus affords optimum thermal insulation for the rod while at the same time satisfactorily resisting the corrosive and/or erosive action of the slag.

The relative wall thickness of the inner and outer strata may vary depending upon conditions. Normally the wall thickness of the inner stratum of thermal insulating refractory material should be substantially greater than the wall thickness of the outer stratum of corrosionand/or erosion-resistant refractory material; in a preferred form the wall thickness of the inner stratum is 3,456,690 Patented July 22, 1969 as least double the wall thickness of the outer stratum. There may, however, be special cases in which the wall thickness of the outer stratum may equal or even exceed the wall thickness of the inner stratum. The corrosionand/ or erosion-resistant material may be selected to counteract the action of a particular slag. If a highly corrosive slag is to be dealt with the refractory material may be selected for its resistance to corrosion while if a highly erosive slag is to be dealt with the refractory material may be selected for its resistance to erosion. In certain cases the material may be one having both optimum resistance to corrosion and optimum resistance to erosion or it may have properties such that it would be selected as a compromise between a material having optimum resistance to corrosion and one having optimum resistance to erosion.

The inner stratum is of refractory material having relatively great thermal insulating capacity while the outer stratum is of refractory material having relatively great corrosion and/or erosion resistance. In a preferred form the inner stratum may be of at least one material selected from the group consisting of zirconia, bubble alumina and refractory clay while the outer stratum may lbe of at least one material selected from the group consisting of alumina, magnesia, a mixture of refractory clay and graphite, Zircon and spinel. In another preferred form the inner stratum may be of at least one material selected from the group consisting of bubble alumina and refractory clay while the outer stratum may be of at least one material selected from the group consisting of zirconia, alumina, magnesia, a mixture of refractory clay and graphite, Zircon and spinel.

Preferably the ends of the outer stratum are in the same transverse planes as the ends of the radially outer portion of the inner stratum and the sleeve has at one end an externally tapered endwise projection and at the other end a recess complementary in shape to the projection to receive a like projection of an identical sleeve.

More specifically, the sleeve may comprise an inner hollow cylindrical stratum of thermal insulating refractory material having at one end an externally tapered endwise projection at the radially inner portion thereof and at the other end a recess complementary in shape to the projection to receive a like projection of an identical sleeve and an outer hollow cylindrical stratum of corrosionand/ or erosion-resistant refractory material disposed about the inner hollow cylindrical stratum in close embracement therewith with its ends in the same transverse planes as the ends of the radially outer portion of the inner hollow cylindrical stratum.

The sleeve may be made by providing a hollow cylinder of corrosion and/or erosion-resistant refractory material, inserting thereinto a pug of formable thermal insulating refractory material and forcing a forming mau- `drel axially through said pug to form Ia hollow cylindrical inner stratum of the thermal insulating refractory material Within the hollow cylinder of corrosion and/or erosion-resistant refractory material. As above indicated, desirably there is formed at one end of the sleeve an externally tapered endwise projection and at the other end of the sleeve a recess complementary in shape to the projection to receive a like projection of an identical sleeve.

Alternatively the sleeve may be made by inserting into a generally cylindrical mold a first pug of formable corrosion and/or erosion-resistant refractory material, forcing a forming mandrel axially through the first pug to form a hollow cylindrical outer stratum of the corrosion and/or erosion-resistant refractory material, inserting thereinto a second pug of formable thermal insulating refractory material and forcing a forming mandrel axially through the second pug to form a hollow cylindrical inner stratum of the thermal insulating refractory material within the hollow cylindrical outer stratum of corrosion and/ or erosion-resistant refractory material.

The tapered endwise projection and complementary recess may be formed entirely in the material of the inner stratum, particularly when the wall thickness of the inner stratum is greater than the wall thickness of the outer stratum.

The sleeve may be made by various other processes known to those skilled in the art, for example, by appropriate selection and combination of pressing, extruding, casting, ramming, jiggering or other steps. The inner and outer strata may be separately preformed and the inner stratum may be pressed into the outer stratum with suitable cement or other adhesive between the strata to cause them to permanently adhere to each other. The separately formed strata may be thus assembled either when in the green state or after having been fired.

Other details, objects and advantages of the invention will become apparent as the following description of a present preferred embodiment thereof proceeds.

In the accompanying drawings I have shown a present preferred embodiment of the invention in which:

FIGURE 1 is an axial cross-sectional view through a composite sleeve for ladle stopper rods embodying my invention, and

FIGURES 2-5 are reduced scale diagrams illustrating successive steps in one method of forming the sleeve.

Referring first to FIGURE l, the sleeve is designated generally by reference numeral 2 and comprises an inner stratum 3 of thermal insulating refractory material which purely by way of example may be deemed to be refractory clay .and an outer stratum 4 of corrosionand/or erosion-resistant refractory material which purely by way of example may be deemed to be a mixture of refractory clay and graphite. As shown in FIGURE l the wall thickness of the inner stratum 3 is substantially greater than the wall thickness of the outer stratum 4 and indeed is at least double the wall thickness of the outer stratum 4.

The sleeve has at one end (the upper end viewing FIGURE l) an externally tapered endwise projection 5 and at the other end (the lower end viewing FIGURE l) a recess 6 complementary in shape to the projection 5 to receive a like projection of an identical sleeve. In the form shown the projection 5 and recess `6 are both formed entirely in the inner stratum 3 because of the relatively great wall thickness of the inner stratum. In other cases the projection and recess may be formed partly in the inner stratum and partly in the outer stratum. As shown in FIGURE l the ends 7 of the outer stratum 4 are in the same transverse planes las the ends 8 of the radially outer portion of the inner stratum 3. The overall shape of the sleeve 2 is conventional. A series of such sleeves are disposed about the steel ladle stopper rod, the bottommost sleeve being in juxtaposition to the stopper head, normally in the orientation shown in FIGURE 1, i.e., with its recess 6 disposed downwardly and its projection 5 disposed upwardly, although in particular cases it may be turned upside down. The sleeves may, for example, be used in a structure of the type disclosed in Patent No. 3,281,904, which structure embodies an insert disposed in a well of the stopper head and overlying a ange at the bottom of the stopper rod, the downward thrust of the sleeves being transmitted through the insert to the rod ange thereby relieving the thin upper wall portion of the stopper head of stress imposed by the sleeves when the stopper is thrust down into the ladle nozzle. The sleeves above the bottommost sleeve are normally oriented similarly to the bottommmost sleeve, each having the projection of the sleeve above or below it received in its recess. The sleeves are stacked one upon another about the rod ange to a level above the top of the ladle since it is normal in open hearth practice to lill the ladle almost to ,may be highly corrosive and/or erosive and may seriously corrode and/or erode the sleeves, particularly those sleeves at about the level of the top of the ladle which are subjected to the action of the slag for a considerably longer period of time than the sleeves below which are immersed in molten steel. The sleeves in the region of the top of the ladle are immersed in molten slag during the latter portion of the tapping of the furnace and during the time during which the ladle is being trans ported from the furnace to the line of ingot molds. During teeming the level of molten steel and slag in the ladle drops during the pouring of each ingot so that the sleeves which were initially immersed in the molten steel are subjected to the action of the corrosive and/or erosive slag for a relatively short period of time. Therefore it may be desired in some cases to use my special sleeves in the region of the top of the ladle while using conventional sleeves therebelow.

Referring now to FIGURES 2-5, there is shown a cylindrical mold 9 open at the top and seated on an annular base 10. In FIGURES 2 and 3 a ring 11 is disposed within the mold 9 and seated on the base 10. A cylindrical pug 12 of formable corrosionand/or erosion-resistant refractory material is dropped into the mold 9 as shown in FIGURE 2. The outside diameter of the pug 12 is such that the pug substantially tits into the mold 9 but with enough clearance to enable the pug to be easily introduced into the mold. The pug 12 seats on the ring 11 and its upper surface is substantially at the level of the upper surface of the mold 9.

A cylindrical forming mandrel 13 with a rounded nose as shown in FIGURE 3 and the diameter of which is such that it fits closely within the ring 11 is then moved axially downwardly through the pug 12 and then withdrawn upwardly, forming the pug 12 into the hollow cylinder of outer stratum 4 within the mold 9, the external diameter of the hollow cylinder 4 being equal to the internal diameter of the mold 9 and the internal diameter of the hollow cylinder 4 being equal to the internal diameter of the ring 11.

In FIGURE 3 the mandrel 13 is shown on its upstroke after having moved down through the pug 12 to form the hollow cylinder 4. Some of the material of the pug will have been extruded downwardly and upwardly below and above the mold, FIGURE 3 showing the hollow cylinder 4 after trimming off of the extruded material. The mandrel 13 is withdrawn upwardly completely out of the mold 9 and the hollow cylinder 4 formed therein. The hollow cylinder 4 is of corrosionand/or erosionresistant refractory material which in the example given is a mixture of refractory clay and graphite.

After formation of the hollow cylinder 4 the ring 11 is replaced by a ring 15 having the same outside diameter as the ring 11 and having a smaller internal diameter and being provided with an upwardly extending externally tapered annular projection 16 surrounding its central bore. The hollow cylinder 4 seats on the outer portion of the ring 15 with the projection 16 extending up into the bottom of the hollow cylinder 4.

A pug 17 of formable insulating refractory material which in the example given is refractory clay is dropped into the mold 9 within the hollow cylinder 4 as shown in FIGURE 4, the outside diameter of pug 17 being such that it substantially ts within the hollow cylinder 4 but with suicient clearance to allow it to be easily inserted. The pug 17 seats on the projection 16 as shown in FIG. URE 4 and its upper surface is at the level of the upper surface of the mold 9 and the hollow cylinder 4.

A forming mandrel 18 shown in FIGURE 5 having a rounded nose and whose outside diameter is such that it ts closely within the ring 15 is then forced downwardly through the pug 17 forming the pug 17 into the inner hollow cylinder of stratum 3 as shown in FIGURE 5. Some of the material of the pug;.17 is forced downwardly outside the projection 16 to form the recess 6 in the bottom of the stratum 3. The mandrel 18 is connected with a plate 20 having an annular recess 21 about the mandrel, which recess is of complementary shape with respect to the projection 16. When the mandrel 18 and plate 20 reach their lowermost position some of the material of the stratum 3' is forced upwardly into the recess 21 forming the upward externally tapered annular projection 5 on the stratum 3. The mandrel 18 is shown in FIGURE 5 as on its upstroke after having been projected downwardly until the plate 20 is seated atop the mold 9. Some of the materialof the pug 17 has been extruded downwardly through the central opening' in the ring 15. Also near the end of the downward movement of mandrel 18, a small amount of material from cylinder 4 has been extruded outwardly between the top of the mold 9 and the plate 20 as indicated by arrows 22.

Thus the stratum 3 is formed within the hollow cylinder 4 which constitutes the outer stratum of the sleeve. The materials of the inner and outer strata are pressed tightly together and joined and the line of juncture between the inner and outer strata may be somewhat irregular as shown at 19 due to the pressure imposed although when the outer hollow cylinder or stratum 4 has been formed under considerable pressure it will substantially retain its shape while the inner stratum is being formed within it.

Both the inner and outer strata during formation are formable, being of the consistency of clay. After the composite sleeve has been formed it is removed from the mold and fired in a kiln to produce the ultimate sleeve for protecting a metal stopper rod comprising a unitary hollow cylinder having an outer stratum of corrosionand/or erosion-resistant refractory material and an inner stratum of thermal insulating refractory material.

While I have shown and described a present preferred embodiment of the invention it is to be distinctly understood that the invention is not limited thereto.

I claim:

1. A sleeve for protecting a metal stopper rod comprising a refractory unitary hollow cylinder having an outer stratum and an inner stratum, the material of the outer stratum having a greater resistance to corrosion and erosion than the material of the inner stratum and the material of the inner stratum having a greater thermal insulating effect than the material of the outer stratum.

2. A sleeve as defined in claim 1 in which the wall thickness of the inner stratum is substantially greater than the wall thickness of the outer stratum.

3. A sleeve as claimed in claim 2 in which the wall thickness of the inner stratum is at least double the wall thickness of the outer stratum.

4. A sleeve as claimed in claim 1 in which the inner stratum is of at least one material selected from the group consisting of zirconia, bubble alumina and refractory clay and the outer stratum is of at least one material selected from the group consisting of al-umina, magnesia, a mixture of refractory clay and graphite, Zircon and spinel.

5. A sleeve as claimed in claim 1 in which the inner stratum is of at least one material selected from the group consisting of bubble alumina and refractory clay and the outer stratum is of at least one material selected from the group consisting of zirconia, alumina, magnesia, a mixture of refractory clay and graphite, Zircon and spinel.

6. A sleeve as claimed in claim 1 in which the ends of the outer stratum are in the same transverse planes as the ends of the radially outer portion of the inner stratum, the sleeve having at one end an externally tapered endwise projection and at the other end a recess complementary in shape to the projection to receive a like projection of an identical sleeve.

References Cited UNITED STATES PATENTS 2,197,515 4/ 1940 Bruce 251-319 `3,318,340 5/1967 Torti 138-140 3,379,409 4/ 1968 Fitzpatrick 251-319 LOUIS K. RIMRODT, Primary Examiner U.S. C1. X.R. 251-319; 266-42