US3430682A - Apparatus for lining a hot top - Google Patents

Description

March 4, 1969 Wl M, CHARMAN, JR ETAL 3,430,682

APPARATUS FOR LINING A HOT TOP Filed June 50. 1965 sheet of 4 INVENTORS WALTER M. CHARMAN JR.

WALTER R. BEATTIE ATTORNEYS March 4, 1969 w, M, CHARMAN, JR, ETAL 3,430,682

APPARATUS FOR LINING A HOT TOP Sheet Filed June 30, 1965 4J FIG. 3

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INVENTORS WALTER M. CHARMAN JR.

WALTER R. BEATTIE ATTORNEYS March 4, 1969 w, M, CJHA-RMAN, |R ET AL 3,430,682

APPARATUS' FOR LINING A HOT TOP Sheet Filed June 50, 1965 INVENTORS WALTER M. CHARMAN JR. WALTER R. BEATTIE FIC-).5

ATTORNEYS March 4, 1969` w. M. CHARMAN, JR.. ET AL 3,43682 APPARATUS-FOR LINING A HOT TOP Filed June 30, 1965 Sheet 4 of 4 f FIGB INVENTORS l WALTER M. CHARMAN JR.

WALTER R. BEATTIE A'ITQRNEYS United States Patent O 8 Claims 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 self-sustaining layer by supplying a setting 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. yPatent 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. Suicient molten steel is poured to till 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 ingot mold is solidifying, thereby providing a reservoir of molten steel to feed molten steel to satisfy the shrinkage occurring in the solidifying ingot.

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 casing lined with a refractory material, Iwhich may be insulating brick, tire 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 ingot after the ingot has been poured and the blocks knocked out. The bottom surface 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 lire brick. Structurally, insulating re brick is soft, porous, and wea'k and the veneer layer is used to protect the face of the fire 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 insulating 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 tire clay 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 re 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,

3,430,682 Patented Mar. 4, 1969 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 ctile 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 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 ame or other heat source.

While the wet mud practice has been successful, it is 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 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.

An overdried veneer and/ or bottom ring caused by being subjected to too high a drying te-mperature 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 Abottom ring to fall olf the lining and casing into the ingot mold during the handling 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 bottom 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% veneer which is normally applied to the refractory only. Moreover, the wet mud materials used required large amounts of water to give the material the proper 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 a veneer layer is formed on the refractory semipermanent hot top lining by introducing an anhydrous iictile material comprised of refractory particles and a bonding agent into a mold cavity formed by the lining and a mandrel and setting the bonding agent by applying a setting agent applied through 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 veneer layer on the refractory lining of a hot top in which tictile material comprised of refractory particles, such as sand, and a thermosetting resin is introduced between the lining and a heated mandrel to quickly set the material and bond the particles into a selfsustaining veneer layer.

A fruther object of the present invention is to provide a new and improved method of forming a veneer on the refractory lining of ya hot top comprising a refractory lined iron casing wherein a mandrel is used to form a mold cavity for ctile material which may be quickly set and molded into a self-sustaining veneer by the application 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 casing.

Another object oft he present invention is to provide a new and improved method of forming a veneer on the inside of a hot top and a bottom protective refractory ring on the bottom of the hot casing, wherein a mandrel 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 casing, by the application of heat or other setting agent.

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 been poured, thus eliminating the refractory ring debris from the ingot sink head junction Vwhen the ingot is stripped from the ingot mold, and preventing this refractory material from contaminating the ingot soaking pits, and more importantly, becoming entrapped and rolled into the ingot surface during rolling at the hot top junction, resulting in loss of yield due to bad surface.

In accordance with the present invention, a mandrel is inserted into the central opening 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 ictile material comprised of refractory particles, e.g., sand, and a settable bonding agent, e.g., a thermosetting resin, is introduced into the veneer and/ or ring cavity by means associated with the mandrel. The preferred bonding agent is a thermosetting resin which, when a setting agent in the form of heat is applied, sets and welds the particles of sand into a monolithic veneer and/or bottom ring 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 agent to set the bonding 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 ring is also molded to the hot top casing, a means of heating the bottom of the bottom casing when 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. 1 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. l;

FIG. 3 is an elevational view of a different form of f 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 modied 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. 1 illustrates a simplified apparatus for practicing the present invention. The apparatus shown in FIG. l 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 insulating material. In the illustrated hot top, the refractory lining 13 is supported between upper and lower annular ledges 15, 16 at the top and bottom of the hot top casing. When the hot top is in use, the bottom of the hot top oats 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 openings in the hot top casing. The conventional clips are not shown in the drawings and preferably are eliminated in accordance with one feature of the present invention.

In FIG. 1, the hot top 11 is shown 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 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 mandrel and the upper ledge when the hot top is positioned on the mandrel.

After the hot top is in position on the mandrel, free flowing, dry, fictile refractory material, preferably in the form of a sand coated or mixed with a settable bonding agent 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 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 configuration to the face of the refractory lining. After the iictile material is introduced 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 ictile material is comprised of refractory 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 has -a plurality of burners 25 inside of the mandrel for heating the mandrel. The burners are supported on a plurality of vertical pipes or manifolds 23 which Irise from the plenum chamber 20 and each manifold has a plurality of burners spaced lengthwise therealong yand 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 chamber, the pipes 23 being mounted in openings in the top of the plenum chamber and communicating with the interior thereof. The bottom 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 intervals along the inner sides of the exterior walls of the mandrel and at the corners of the mandrel, the manifolds -are provided with a plurality of burners including burners directed to a corner panel of the mandrel which joins adjacent sides of the mandrel and burners which are directed to the adjacent sides.

In the preferred practice, the mandrel is maintained in a heated condition and the hot tops are set down over and removed from the mandrel while the mandrel is hot. By maintaining the mandrel heated, the setting of the resin is accomplished at a maximum speed after the Iictile 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 lictile material may be blown into the cavity to introduce the lictile `material with sufficient velocity and at a suicient speed to assure that the material docs not prematurely set and form bridges in the veneer cavity.

In the embodiment of FIG. 1, the ctile material is shown as being supplied from a pail-like structure yHS- sociated with the mandrel and it will be understood that the pail-like structure is one which is removable from its illustrated position to allow the hot top to move onto and oif of the mandrel. Alternatively, the pail-like structure could be xed and the mandrel movable to enable the hot top first to be positioned in alignment 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.

Preferably, 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 the inner periphery of the bottom ledge and the central portion of the bottom ring. When the ctile material is directed into the veneer cavity, the ctile material will flow into the space 30 to till 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 though there is not necessarily an actual bond between the refractory lining and the veneer layer but rather a physical intertting. 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 con- Veyorized system and have been given the same 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 ts between the conveyors 40, 41, but the length of the plenum chamber along the conveyor is `such that it extends underneath the bottom ring to pick up the hot top when the mandrel and plenum chamber are raised. Prefer- -ably pads 43 shown in FIG. 3 are positioned between the bottom rin-g 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 against an annular outlet funnel 45 of a hopper 46 shown in FIG. 3. The annular funnel is open at the bottom so that free flowing 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 the funnel, the open bottom of the funnel registers with the annular space between the mandrel and the hot top so that the material will ow from the funnel into the veneer cavity dened by the hot top and mandrel.

The ctile material is supplied to the funnel 45 from the hopper 46 which has a conical bottom 49. A plurality of outlet 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 baille 52 therein which may be rotated to block the ilow of sand. The bales may be controlled by a suitable mechanism such that all bafes 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. l 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 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 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 lbottom ledge 16 to form a mold cavity B for the bottom ring of the hot top. The bottom portion 51 of the mandrel includes a generally horizontal portion 51a and an upwardly extending portion 51b 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 FIG. 5, the bottom ledge 16 of the hot top has an upwardly and inwardly tapering inner surface dening a receiving opening for a tapered central portion of the ring. The mandrel has a corresponding tapered central portion extending upwardly from the bottom portion of the mandrel.

The mandrel M is shown as being heated, as in the first described embodiment, by a set of burners 53 which are disposed along pipes 53a extending along the inside of the mandrel and which receive an air-gas mixture from a 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 eX- tending portion 51b of the mandrel. The upper ends of the vertical portions 55 of the pipes 53 extend horizontally above the mandrel portions 51b and have a valve controlled burner 57 iixed thereto for heating the casing of the hot top adjacent its lower periphery. In the embodiment of FIG. 5, the hot top does not rest upon the manifold or chamber for supplying the gas-air mixture to the mandrel but rests upon blocks 58 which engage a downwardly facing shoulder on the casing. The hot top may be set down over the mandrel by any suitablehot top handling means.

In the embodiment of FIG. 5, the mold cavity formed by the mandrel is supplied with ctile 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 has an outlet 61 with an annular passage 62 '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 ctile material is initially introduced into the blow chamber 60 from a hopper 64 and is moved from the hopper 64 into the blow chamber through a conduit 65 interconnecting the bottom of the hopper 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 chamber have valves 68, 69 respectively for controlling the ilow of tictile 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 shown at 70 in FIG. 6 and 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 mandrel and hot top to prevent the thermosetting material from curing in the blow chamber and manifold. After a dwell time suicient to cure the thickest section formed in the cavity, the hot top is stripped from the mandrel and 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 heatl respectively to this section. The material in the bottom ring cavity may also be heated during the curing by using the burners 57 to heat the casing.

The interior surface of the bottom ledge 16 of the casing may be cut back, that is, tapered upwardly and outwardly of the hot top as shown in FIG. 7 to provide a locking engagement of the molded ring on the casing. Moreover, a strap 71 for holding the ring in position on the hot top may be rst positioned on the mandrel, as illustrated in FIG. 7. The strap has a rst section which extends upwardly into the cavity and a horizontal portion which extends into the ring cavity B, and the portions 72 of the strap may be struck out for locating and supporting the strap in the cavity. The strap will aid in tying the ring to the remainder of the hot top structure.

The new and improved method of applying a refractory layer to the inside of a hot top casing may also be used where the hot top is to be made up in an inverted position. Referring to FIG. 8, such a hot top structure shown fragmentarily in section and indicated by the reference numeral 75, is positioned over a mandrel 76 which, while shown as a cylindrical mandrel, is heated as in the first described embodiment. When the hot top is positioned on the mandrel, it defines a mold cavity A for the layer to be applied to the inside of the hot top casing and the casing of the hot top has a top ledge which, in the inverted position of the hot top, rests on a table for supporting the hot top and extends inwardly to the mandrel to close the bottom of the mold cavity A. The hot top casing has a bottom ledge which, in the inverted position of the casing, is at the top of the casing and a bottom ring 80 is disposed on the bottom ledge 78 and has ports 81 therethrough for supplying anhydrous fctile material to the mold cavity A. The ports 81 may register with outlet ports 82 in a blow chamber which is lowered onto the ring when the fictile refractory material is to be supplied to the mold cavity A. The blow chamber 83 and the bottom ring 80 may have cooperating interengaging portions to properly position the ports 82 and the ports 81 In the preferred practice, the mandrel is heated to set the fctile material into a self-sustaining layer and the blow chamber 83 is removed from the top of the bottom ring 80 as soon as the material is blown into the veneer cavity. The removal of the blow chamber 83 immediately after blowing the material into the mold cavity A minimizes the opportunity for the material in the blow chamber to be affected by the heat of the mandrel. Moreover, the bottom refractory ring 80 provides insulation between the blow chamber 83 and the mandrel and as is illustrated in the drawings enables the blow chamber to be spaced so that it does not contact the mandrel or any metal parts directly heated from the mandrel. To this end the bottom ring may have an internal lip 85 which extends over the top of the mandrel between the blow chamber 83 and the mandrel.

In addition to the advantages pointed out above, a new refractory ring 80 is used with each hot top to be made up and this always provides a clean surface 4between the blow chamber ports and the mating ports on the hot top ring.

While in the preferred and illustrated embodiments, the mobile ctile material is comprised of refractory particles mixed or coated with a thermosetting plastic resin for bonding the particles together, it will be recognized that other setting agents might be utilized and the mandrel provided with the proper means for eifecting a setting of the agents prior to the withdrawal of the mandrel. For example, certain bonding agents are gas or chemically settable and the mandrel could be provided with means for gassing and chemically setting the layer. Moreover, the mandrel could be used to apply a layer directly to the casing itself.

While the preferred practice of the invention is to introduce the material while the mandrel is hot and at a suflicient rate of speed to prevent bridges from forming to block the ow of material into the cavity to ll the latter, it will be understood that the mandrel could be heated after the sand or material is introduced to the cavity. Moreover, in the preferred practice, the hot top is preferably hot from the preceding use when the thermosetting material is introduced, particularly, if the bottom ring is to be connected to the hot top casing by means of the bonded material, or is to be molded in situ. In each of the described embodiments, suitable temperature regulating means may be used for the mandrel.

While the present invention has been described with reference to particular embodiments, it is hereby our intention to cover other modifications and constructions which will occur to those skilled in the art and which fall within the scope and spirit of the present invention.

We claim:

1. In an apparatus for applying a veneer layer to the side walls of a central opening of an annular hot top structure where the central opening extends longitudinally inwardly from one end of the hot top structure to the other, a mandrel comprising a body member having an end portion adapted to be disposed in said opening in telescoped relationship with respect to said hot top structure to provide with the mandrel and the side walls of the central opening a mold cavity for forming the veneer layer, means associated with said mandrel for supplying ilowable material to said cavity, said flowable material comprising a settable binder curable in response to a setting agent to bond said particles into a self-sustaining veneer layer, said mandrel including means for applying said setting agent to said material in said cavity to elect a setting of said binder, said apparatus further including wall members defining with the hot top structure a mold cavity for a ring which covers one end of the hot top structure and said means for applying said setting agent including means for supplying setting agent from said wall members on all sides of the ring cavity.

2. In an apparatus for applying a veneer layer to the exposed face of a refractory lining of a hot top comprised of a refractory lined, open ended, metal casing, the apparatus including a mandrel adapted to be telescoped into said lined casing from one end whereby the exterior of the walls of the mandrel dene with the lining of the casing a mold cavity for the veneer layer, means associated with and exteriorly of said mandrel for introducing into said mold cavity fictile material comprised of refractory particles and a thermosetting resin, said mandrel including means for heating the external walls thereof to a predetermined temperature sufficient to set said resin to bond said refractory particles into a self-sustaining layer, said heating means including heating elements within said mandrel and distributed along the walls of said mandrel.

3. An apparatus for applying a layer of refractory material to the interior of a hot top structure having a metal casing with an opening therethrough and for providing the casing with a ring which covers an outer end wall of the casing at one end of the casing, the apparatus comprising a mandrel adapted to be disposed in telescoped relationship in said casing by relative movement of said casing and mandrel to insert said casing onto said mandrel from said one end, said mandrel when in telescoped position being spaced from the sidewall of the opening in the hot top which receives the mandrel to provide with the side wall a mold cavity for said layer, said mandrel further having a portion extending outwardly in superposed relation with said one end of said casing and in spaced relationship thereto to deline with said casing a ring cavity for said ring which cavity communicates with said cavity for said layer, said portion including a substantially continuous extension extending axially of the mandrel adjacent the outer periphery of said casing to define the outer side wall of said ring cavity, means associated with said mandrel for supplying fictile material to the cavities defined by said mandrel, said fictile material being comprised of refractory particles and a bonding agent curable upon the application of a setting agent to bond said particles into a self-sustaining layer, and means for supplying said setting agent from said mandrel including from said portion and said extension to cure the material in said cavities.

4. An apparatus according to claim 3 wherein said bonding agent is a thermosetting resin and said mandrel has heating means for heating the walls of the cavities formed by said mandrel.

5. An apparatus according to claim 4 in which said mandrel includes means for selectively heating the lower portion of said casing adjacent said ring cavity.

6. An apparatus according to claim 4 wherein said means for supplying fictile material is removable from its association with said mandrel and structure whereby it may be removed therefrom prior to the operation of said heating means to cure said material.

7. In an apparatus for lining the Wall of the central opening in an annular hot top structure, a mandrel adapted to be `disposed in telescoped relationship with said hot top structure and having exterior walls for forming the side walls of a mold cavity for said lining, means associated with and exteriorly of said mandrel for supplying owable material to said cavity, heating means within said mandrel for heating the cavity defined by the ex- 10 terior walls of said mandrel, said heating means including a plurality of burners distributed along the walls of said mandrel for effecting the heating of the entire surface area of said mandrel defining walls of said mold cavity.

8. An apparatus as defined in claim 7 wherein said apparatus includes wall members defining a cavity for a ring for covering one end of said structure, and said heating means includes means for heating the entire cavity dening surfaces of said wall members.

References Cited UNITED STATES PATENTS 2,565,829 8/1951 Wedlake 164-159 X 2,942,319 6/1960 Anthony 160-33 X 2,988,793 6/1961 Withee et al 164--159 3,004,312 10/1961 Froberger 164-21 3,210,810 10/1965 Potter 164159 WILLIAM I. STEPHENSON, Prz'maly Examiner.

EUGENE MAR, Assistant Examiner.

U.S. C1. X.R.

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