[1]United States Patent Office @,430,682 3,430,682 APPARATUS FOR LINING A HOT TOP Walter M. Charman, Jr., Shaker Heights, and Walter R. Bi@attie, Independence, Ohio, assignors to Oglebay Norton Company, Cleveland, Ohio, a corporation of Delaware Filed Jitne 30, 1965, Ser. No. 468,339 U.S. Cl. 164-159 8 Claims Int. Cl. B28b 19100; B29f 5100; B22c 25100 ABSTRACT OF THE DISCLOSURE The hot top is lined by inserting a mandrel into the hot top and flowing the lining material from the hot top into the side walls of the hot top opening and by setting the material into a selfsustainin.- layer by supplying a settin.- agent from the mandrel. The present invention relates to an improved apparatus for readying a hot top for use with an ingot mold. The invention is an improvement on the apparatus described in Withee et al. Patent No. 2,988,793 and Anthony Patent No. 2,896,266. In one method of casting an ingot of steel, a hot tOP is associated with the upper end of the ingot mold and molten steel is poured into the ingot mold through the central opening in the hot top. Sufficient molten steel is poured to fill the mold and the hot top. The hot top is a heat insulator and maintains steel therein in a molten condition while the steel in the ingqt mold is solidifying, thereby providing a reservoir of molten steel to, feed molten steel to satisfy the shrinkage occurring in the solid;fying in.-ot. The hot top which is to be readied for use by the present invention is the type of hot top which is comprised Of a metal casin.- lined with a refractory material, which may be insulating brick, fire brick, cast insulating material or other iunsulating material of a temperature duty and class suitable for the use intended. The type of hot top described is normally blocked inside the top of the ingot mold and moves downward with the solidifying steel of the in-ot after the ingot has been poured and the blocks knocked out. The bottorn stirface of the cast iron hot top casing is prevented from coming into contact with the molten steel in the ingot mold by a refractory bottom ring which is normally a manufactured component and is replaced after each use. Veneer layers are used in hot tops to protect the refractory lining and/or to provide an additional layer of insulation in the hot top. In one type of hot top, a veneer layer is used to@ protect the exposed face of commercial insulating fire brick. Structurally, insulating fire brick is soft, porotis, and wez@k and the veneer layer is used to protect the face of thefire brick against mechanical damage and also from damage due to thermal shock by providing a temperature drop between the molten steel and the brick so that the instilating brick is not directly exposed to temperatures which are beyond the operating temperature of the brick. In another type of hot top, a refractory lining is comprised of commercial fire ciay brick which is relatively hard, dense and strong. However, in some cases it is desirable to apply a layer of insulating material to the face of the fire clay brick. Other refractory materials such as the equivalent castables are also used to line metal hot top casings and it will be recognized that the present invention is applicable where it is desirable to apply a veneer layer to the face of any such lining which would be exposed to the molten steel in absence of the veneer layer. In the aforesaid Withee et al. patent, either the prOtective veneer or the bottom ring, or both, are applied to the insulating lining and/or the bottom ring on the casing, Patented Mar. 4, 1969 2 with the use of a mandrel which is positioned in the hot top to form a mold cavity between the mandrel and the lining and/or also the bottom hot top casing. Fictile refractory material is then forced into the mold cavity to form the veneer layer on the lining and/or the bottom refractory ring. In the Withee et al. patent, the fictile material is applied as a moldable mass containing water, sometimes referred to as "wet mud," and after the mandrel has been removed leaving the wet veneer layer on 10 the insulating lining and/or the bottom ring on the casing, this wet material must be thoroughly dried by two hours or @more exposure to low heat from a gas flame or other heat source. While the "wet mud" practice has been successful, it is 15 necessary in practice to make sure that the veneer and/or bottom ring layers are completely dry before use in a pouring operation to obviate the possibility of explosively ejecting molten metal from the hot steel. An underdried veneer -or bottom ring containing appreciable moisture 20 can cause a violent "boiling" of the steel in the hot top due to entrapped steam generated during the pouring of the sink head, creating a safety hazard; such "boiling" can also result in unfavorable metallurgical results on some grades of steel. 25 An overdried veneer and/or bottorn ring caused by being subjected to too. high a drying temperature over too long a time can result in the binder in the veneer material being burned out and loss of veneer strength, causing the veneer and/or bottom ring to fall off the lining ahd cas30 ing into the ingot mold during the handlin.@ of the hot top prior to the steel pouring operation. Such loss of veneer and/or ring into the mold can result in inclusions in the steel, and also damage to the hot top lining and casing. The "wet mud" material, when used to mold the bot35 tom ring, is 2" in thickness and requires a drying time far in excess of the two hours required to dry a 1/2" to 3/4" veneer which is normally applied to the refractory only. Moreover, the "wet mud" materials used required lar.-e amounts of water to give the material the proper 40 moldability, particularly when used to form the veneer and/or bottom ring in the make up machine, and when dried in two inch thicknesses is subject to drying cracks. An important object of the present invention is to provide a new and improved method and apparatus in which 45 a veneer layer is formed on the refractory semipermanent hot top lining by introducing an anhydrous fictile material comprised of refractory particles and a bonding a,aent into a mold cavity formed by the lining and a mandrel and setting the bonding agent by applying a setting 50 agent applied tbrough the mandrel to bond the refractory particles into a veneer layer and then removing the mandrel. Another object of the present invention is to provide a new and improved method and apparatus for forming a 55 veneer layer on the refractory lining of a hot top in which fictile material comprised of refractory particles, such as sand, and a thermosetting resin is introduced between the lining and a heated mandrel to qtiiekly set the material and bond the particles into a self-sustaining veneer layer. 60 A fruther object of the present invention is to provide a new and improved method of forming a veneer on the refractory lining of a hot top comprising a refractory lined iron casing wherein a mandrel is used to form a mold cavity for fictile material which may be quickly 65 set and molded into a self-sustainin.- veneer by theapplication of heat or other setting agent by the mandrel to form the lining and to connect the bottom ring to the lower end of the hot top casin,-. Another object oft he present invention is to provide 7o a new and improved method of forming a veneer on the inside of a hot top and a botto-m protective refractory ring on the bottom of the hot casing, wherein a mandrel
[2]3 is used to form a mold cavity between the interior and the bottom of the hot top casing and the mandrel, and wherein fictile material which may be quickly cured and molded into a self-sustaining protective veneer on the lining, and also a self-sustaining bottom refractory ring on the bottom of the casin.-, by the application of heat or other setting a,-ent. A further object of the present invention is to provide a bottom ring which is molded in situ on the bottom of the casing and which is heat collapsible after the ingot has beeia poured, thus eliminating the refractory ring debris from the ingot sink head junction when the ingot is stripped from the ingot mold, and preventing this refractory material from contaminating the ingot soaking pits, and more importantly, becomin@ entrapped and rolled into the in.-ot surface during rollin.- at the hot top jlinetion, resulting in loss of yield due to bad surface. In accordance with the present invention, a mandrel is inserted into the central openin.- of the refractory lined hot top casing to define with the refractory lining of the casing a mold cavity for the veneer layer to be applied to the refractory lining and/or bottom of the hot top casing. After the mandrel is inserted into the hot top opening, anhydrous fictile material comprised of refractory particles, e.-., sand, and a settable bonding agent, e.g., a thermosetting resin, is introduced into the veneer and/or rin.- cavity by means associated with the mandrel. The preferred bonding agent is a thermosettinresin which, when a settin.- agent in the form of heat is applied, sets and welds the particles of sand into a monolithic veneer and/or bottom rin-. layer. The molded layer is then selfsustaining, extremely strong, dry and ready for use and the mandrel can be immediately removed. The mandrel includes means for supplying the setting a.@ent to set the bondin- agent and in the preferred and illustrated embodiments includes means for heating the mandrel to a temperature necessary to effect a bonding of the sand and when the bottom rin.- is also molded to the hot top casing, a means of heating the bottom of the bottom casing whe@l necessary to add heat to this part of the casing to cure or set the bottom ring portion of the assembly. Further objects and advantages of the present invention will be apparent from the following description of the accompanying drawings in which: FIG. I is an elevational view, with portions cut away, of one form of an apparatus for practicing the present invention; FIG. 2 is a cross sectional view taken approximately along line 2-2 of FIG. 1; FIG. 3 is ail elevational view of a different form of apparatus for practicing the present invention; FIG. 4 is a sectional view taken approximately along line 4-4 of FIG. 3; FIG. 5 is an elevational view, with portions cut away, of one form or apparatus for practicing the invention wherein both veneer lining and bottom ring are molded on the hot top lining and casing bottom; FIG. 6 is an enlarged section of wiper strip and mandrel at 16 in FIG. 5; FIG. 7 is a fragmentary sectional view of a modified hot top and mandrel; and FIG. 8 is a fragmentary sectional view showing the use of the present invention with a preformed bottom ring with supply ports. Referring to the drawings, FIG. I illustrates a simplified apparatus for practicing the present invention. The apparatus shown in FIG. 1 comprises a -mandrel 10 adapted to be inserted into the central opening of a hot top 11. The hot top 11 is shown as comprising an iron casing 12 lined with a refractory lining 13 which, as noted above, may be insulating brick of a soft porous nature, or other refractroy insulatin@ material. In the illustrated hot top, the refractory lining 13 is supported between upper and lower annular led-.es 15, 16 at the top and bottom of the hot top casing. When the hot top is in use, the bottom of 3)430,682 4 the hot top "floats" on the solidifying shell of the ingot and the bottom of the iron casing is protected by a refractory ring 18 which is disposed adjacent the underside of the bottom ledge 16. Normally the bottom ring 18 is held in place by conventional clips which engage the ring and which are received in openin-s in the hot top casin.-The conventional clips are not shown in the drawings and preferably are eliminated in accordance with one feature of the present invention. 10 In FIG. 1, the hot top 11 is sbown as disposed over the mandrel 10 and the bottom ring of the hot top rests on a hollow table-like structure 20 at the lower end of the mandrel 10. The hollow table-like structure 20 forms -a plenum chamber for purposes which will be described 15 hereinafter. The mandrel 10 closely fits the inside diameter of the inner wall 18a of the ring 18, which has a downward and inward taper, adjacent the bottom of the ring. Moreover, the inside diameter of the upper ledge 15 of the hot top is such so as to provide clearance between the 20 mandrel and the upper ledge when the hot top is positioned on the mandrel. After t-he hot top is in position on the mandrel free flowin,-, dry, fictile refractory material, prefera@ly in the form of a sand coated or mixed with a settable bonding 25 a,-ent in the form of a thermosetting resin, such as a phenolic thermosetting resin, is poured through the space between the upper annular ledge and the mandrel into the veneer cavity formed by the exterior of the mandrel and the adjacent lining of the -hot top. It will be understood 30 that the exterior configuration of the mandrel, a portion of which is shown in FIG. 2, corresponds to that configuration desired for the exposed face of the veneer layer and normally will correspond in confi.-Uration to the face of the refractory lining. After the fictile material is in35 troduced into the mold cavity, the bonding agent therein is set cured by t-he application of a setting agent from the mandrel to bond the refractory particles into a self-sustaining layer. Preferably the fictile material is comprised of refractory 40 particles coated or mixed with a thermosetting resin and, as in the illustrated embodiment, the mandrel is provided with heating means to heat the mandrel and effect a setting of the resin. In the illustrated apparatus, the mandrel is hollow and 45 has a plurality of burners 25 inside of the mandrel for heating t@he mandrel. The bumers are supported on a plurality of vertical pipes or manifolds 23 which Tise from the plenum chamber 20 and each manifold bas a plurality of burners spaced lengthwise therealong -and 50 disposed to direct the gas flame toward the adjacent wall of the mandrel. A gas-air mixture is supplied to the burners from inside the plenum cbamber, the pipes 23 bein@ mounted in openings in the top of the plenum chamber and communicating with the interior tbereof. The bottom .55 of the plenum chamber has a supply line 28 for supplying a combustible gas-air fuel mixture to the plenum chamber. As is illustrated in FIG. 2, the vertical pipes 23 with the burners 25 thereon are disposed at inter-vals along the 60 inner sides of the exterior walls of the mandrel and at t@he corners of the mandrel, the manifolds are provided with a plurality of burners includin.@ biirners directed to a corner panel of the mandrel which joins adjacent sides of the n-landrel and burners which are directed to the adjacent 65 sides. In the preferred practice, the mandrel is maintained in a heated condition and the hot tops are set down over and ;removed from t@he rnandrel while the mandrel is hot. By. maintaining the mandrel heated, the setting of the 70 resin is accomplished at a maximum speed after the fictile material is introduced into the mold cavity and the time of the hot top on the mandrel is kept to a minimum. If necessary, the fictile material may be blown into the cavity to introduce the fictile material with sufficient velocity 75 and at a sufficient speed to assure that the material does
[3]5 not prematurely set and form bridges in the veneer cavity. In the embodiment of FIG. 1, the fictile material is shown as being supplied from a pail-like structure -associated with the mandrel and it will be understood that the paillike structure is one which is removable from its illustrated position to allow the hot top to move onto and off of the mandrel. Alternatively, the pail-like structure could be fixed and the mandrel movable to enable the hot top first to be positioned in aligmnent with the mandrel and the mandrel then moved into the position shown in FIG. 1. Such an apparatus is illustrated in FIG. 3 and will be described hereinafter. Prefera@bly, the bottom ring 18 of the hot top is formed with a central portion which rises inside of the bottom ledge 16 with a clearance space 30 between t-he inner periphery of the bottom ledge and the central portion of the bottom ring. When the fictile material is directed into the veneer cavity, the fictile material will flow into the space 30 to fill this space. After the veneer layer or the veneer layer and bOttOm ring have been bonded, we have found that the physical connection between the layer and the casing lining is sufficient to hold the veneer layer in position even thou.-h there is not necessarily an actual bond between the refractory lining and the veneer layer bUt Tather a physical interfitting. The relationship between the veneer layer and the ring also is not necessarily an @actual bond. Referring to FIG. 4, a mandrel and plenum chamber of the same type as shown in FIG. 1, is embodied in a conveyorized system and have been given the rame reference numerals as in FIG. 1. The plenum chamber and the mandrel are positioned between conveyors 140, 41 which are adapted to support the hot top and convey the latter to and from a position over the mandrel. The mandrel can be raised and lowered between the conveyors 40, 41 and is movable from the position shown in FIG. 4 to a position where the top of the mandrel is below the upper level of the conveyors 40, 41 to enable the hot top to be moved to and from position. The mandrel may be raised and lowered by a hydraulic ram apparatus indicated at 42. . The width of the plenum chamber 20 is such that it fits between the conveyors 40, 41, but the length of the plenum chamber along the conveyor is such that it extends undemeath the bottom ring to pick iip the hot top when the mandrel and plenum chamber are raised. Prefer-ably pads 43 shown in FIG. 3 are positioned between the bottom ring and the top of the plenum chamber. The upward movement of the plenum chamber and mandrel is preferably such that the hot top is lifted from the conveying elements and moved a-ainst an annular outlet funnel 45 of a hopper 46 shown in FIG. 3. The annular funnel is openat the bottom so that free flowing fi@ctile material poured into the annular chamber of the funnel will run out of the funnel bottom. When the hot top is raised upwardly against t-he funnel, the open bottom of the funnel registers with the annular space between the mandrel and the hot top so that the material will flow from the funnel into the veneer cavity defined by the hot top and mandrel. The fictile material is supplied to the funnel 45 from the hopper 46 which -has a conical bottom 49. A plurality of ouflet pipes 50 connect to the conical bottom 49 at the lower part thereof and are adapted to convey material from the bin 48 into the funnel 45. The outlet pipes '50 each have a baffle 52 therein which may be rotated to block the flow of sand. The baffles may be controlled by a suitable mechanism such that all baffles may be rotated to an open position or to a closed position simultaneously. Since such mechanisms are well known to those skilled in the art, such a mechanism is not illustrated herein. The operation of the apparatus shown in FIG. 3 to mold the veneer layer of refractory material by applying heat from the mandrel is substantially the same as that in FIG. 1 and the description thereof will not be repeated. In the embodiment shown in FIG. 5, the mandrel M is adapted to form a mold cavity, in combination with the lined hot top casing for an interior lining for the inside 3)430)682 6 of the hot top and for a bottom ring on the @underside of the bottom ledge 16 of the hot top casing. As illustrated in FIG. 5, the mandrel has a central portion 50 which is received inside the hot top when the hot top is set down over the mandrel and which defines a mold cavity A for the layer to be applied to the inside of the hot top casing, and a bottom portion 51 which extends outwardly from the central portion underneath the bottom ledge 16 to form a mold cavity B for the bottom ring of the hot top. 10 The bottom portion 51 of the mandrel includes a generally horizontal portion 51a and an upwardly extendina portion Slb at the outer end of the horizontal portion 51a. The upwardly extending portion 51b forms the mold wall for the outer periphery of the bottom ring to be molded. In 15 FIG. 5, the bottom ledge 16 of the hot top has an upwardly and inwardly tapering inner surface defining a receiving opening for a tapered central portion of the ring. The mandrel has a corresponding tapered central portion extendin,@ up-wardly from the bottom portion of the 20 mandrel. The mandrel M is shown as being heated, as in the first described embodiment, by a set of bumers 53 which are disposed along pipes 53a extending along the inside of the mandrel and which receive an air-gas mixture from a 25 chamber 54. The pipes 53a also extend laterally underneath the horizontal portion 51a of the mandrel for forming the ring cavity and have a vertical portion 55 extending upwardly along the outer side of the upwardly extending portion 51b of the mandrel. The upper ends of 30 the vertical portions 55 of the pipes 53 extend horizontally above the mandrel portions 51b and have a valve controlled burner 57 fixed thereto for heatin- the casing of the hot top adjacent its lower periphery. 'In the embodiment of FIG. 5, the hot top does not rest upon the mani35 fold or chamber for supplying the gas-air mixture to the mandrel but rests upon blocks 58 which engage a downwardly facin- shoulder on the casing. The hot top may be set down ove'r the mandrel by any stiitable hot top handling means. 40 In the embodiment of FIG. 5, the mold cavity formed by the mandrel is supplied with fictile material from a blow chamber 60 which is set down on top of the hot top after the hot top is positioned on the mandrel. The blow chamber 60 bas an outlet 61 with an annular passage 62 45 'which registers with the annular mold cavity formed by the mandrel and the hot top casing. Fictile material is blown from the chamber 61 by air supplied through a conduit 63. The fictile material is initially introduced into the blow chamber 60 from a hopper 64 and is moved frorn the 50 hopper 64 into the blow chamber tbrough a conduit 65- interconnecting the bottom of the hoppdr and the top of the blow chamber. The material is moved through the conduit 65 by air supplied to the latter from a pipe 66. The conduit 65 and the outlet passage 62 of the blow cham55 ber have valves 68, 69 respectively for controlling the flow of fictile material therethrough. Before the hot top is set over the mandrel, a one piece or multipiece wiper strip can be placed adjacent the outer wall 51b of ring cavity 13 as sho@vn at 70 in FIG. 6 and 60 the wiper strip will be attached to the bottom ring when the ring is formed in the ring cavity 13. Immediately after the blowing of the sand into the cavities A and B, the blow chamber is preferably lifted from the casing and removed from the proximity of the heated 65 mandrel and hot top to prevent the thermosetting material from curing in the blow chamber and manifold. After a dwell time sufficient to cure the thickest section formed in the cavity, the hot top is stripped from the mandrel and 70 returned to the conveyor sysem. The heated mandrel is made with an extra heavy section of cast iron around the ring cavities since a heavier section of material, i.e., the bottom ring, must be cured in this cavity and the heated mandrel must supply the maximum quantity of heat, re75 spectively to this section. The material in the bottom ring
[4]3)430)682 7 8 cavity m-,Ly also be beated durin.- the curing by using the latter, it will be understood that the mandrel could be burners 57 to heat the casing. heated after the sand or material is introduced to the The interior surface of the bottom ledge 16 of the cascavity. Moreover, in the preferred practice, the hot top in-, may be cut back, that is, tapered upwardly and outis preferably hot from the precedin- use when the thermowardly of the hot top as shown in FIG. 7 to provide a 5 setting material is introduced, part'icularly, if the bottom locking engagement of the molded ring on the casing. ring is to be connected to the hot top casing by means of Moreover, a strap 71 for holding the rin.@ in position on the bonded material, or is to be molded in situ. In each the hot top may be first positioned on the mandrel, as ilof the described embodiments, suitable temperature lustrated in FIG. 7. The strap has a first section which regulating means may be used for the mandrel. extends upwardly into the cavity and a horizontal portion 10 While the present invention ha@s been described with which extends into the ring cavity B, and the portions 72 reference to particular embodiments, it is hereby our of the strap may be struck out for locating and supportintention to cover other modifications and constructions in.- the strap in the cavity. The strap will aid in tying the which will occur to those skilled in the art and which fall ring to the remainder of the hot top structure. within the scope and spirit of the present invention. The new and improved method of applying a refractory 15 We
