SUPERIMPOSED HOT TOP AND SEAL
United States Patent 3794287
A hot top which is adjusted to be superimposed on an ingot mold having an annular recess around the opening in the top of the mold. The hot top can be in the form of a single-use structure or a metal casing having a single-use liner insert unit supported therein. The single use structure and the metal casing are adapted for placement in the recess to form a continuation of the opening in the ingot mold. The structure and the insert liner unit are formed from a heat-destructible refractory material. A heat-destructible gasket formed from a compressible plastic material is secured to the bottom of the structure or the bottom of the panels to form a seal at the juncture of the hot top with the top of the ingot mold.
US Patent References:
HOT TOP FOR BIG-END-UP INGOT MOLDS AND METHOD OF ASSEMBLING SAME
Eastwood et al. - July 1969 - 3458169
Hot top for ingot molds
Ramage - October 1928 - 1689175
Hot top and mould assembly
Kauffman - December 1958 - 2863192
Hot-top for ingot molds
Mellinger et al. - June 1964 - 3136012
REFRACTORY PANEL UNIT WITH HINGE MEANS AND FRANGIBLE PORTIONS
Charman et al. - November 1969 - 3478999
HOT TOP FOR BIG-END-UP INGOT MOLDS AND METHOD OF ASSEMBLING SAME
Eastwood et al. - July 1969 - 3458169
Hot top for ingot molds
Ramage - October 1928 - 1689175
Hot top and mould assembly
Kauffman - December 1958 - 2863192
Hot-top for ingot molds
Mellinger et al. - June 1964 - 3136012
REFRACTORY PANEL UNIT WITH HINGE MEANS AND FRANGIBLE PORTIONS
Charman et al. - November 1969 - 3478999
Application Number:
05/191206
Publication Date:
02/26/1974
Filing Date:
10/21/1971
View Patent Images:
Export Citation:
Assignee:
Thiem Corporation (Milwaukee, WI)
Primary Class:
Other Classes:
249/201
International Classes:
B22D7/10; B22D7/00; B22D7/10
Field of Search:
249/106,197-201
Primary Examiner:
Baldwin, Robert D.
Attorney, Agent or Firm:
Barry, Ronald Nilles James E. E.
Parent Case Data:
RELATED APPLICATION
This application is a continuation-in-part of my copending application Ser. No. 844,754, filed on July 25, 1969 and entitled "Superimposed Hot Top and Seal", now abandoned.
Claims:
I claim
1. A hot top which is adapted to be superimposed in a recess at the top of an ingot mold having a central cavity, said hot top comprising:
2. The combination in accordance with claim 1 including
3. The combination according to claim 1 wherein said compressible gasket is completely enclosed within a combustible wrapper and further including means for securing said wrapper to said panel insert unit.
4. The combination according to claim 1 wherein each of said panels includes a recess and said compressible gasket is positioned in said recess and
5. The combination of an ingot mold having a central cavity and a groove having an outwardly tapered wall around the top of said cavity and a hot top adapted to be seated in said groove, said hot top including
1. A hot top which is adapted to be superimposed in a recess at the top of an ingot mold having a central cavity, said hot top comprising:
2. The combination in accordance with claim 1 including
3. The combination according to claim 1 wherein said compressible gasket is completely enclosed within a combustible wrapper and further including means for securing said wrapper to said panel insert unit.
4. The combination according to claim 1 wherein each of said panels includes a recess and said compressible gasket is positioned in said recess and
5. The combination of an ingot mold having a central cavity and a groove having an outwardly tapered wall around the top of said cavity and a hot top adapted to be seated in said groove, said hot top including
Description:
BACKGROUND OF THE INVENTION
Hot tops are conventionally used to form a sinkhead at the top of an ingot mold. The sinkhead isolates the shrinkage cavity formed on solidification of the ingot in a reduced volume section at the top of the ingot. The sink-head is then cropped from the ingot. These hot tops are commonly referred to as floating-type hot tops and are inserted partially into the opening in the top of the mold. Heat-destructible insulating panels and single-use bottom ring assemblies are used to protect the surfaces of the casing as shown in U.S. Pat. No. 3,437,308. The bottom ring assembly also provides a seal between the hot top and the inside surface of the ingot mold. The sinkhead which is formed with this type of hot top is spaced inwardly from the outside edges of the ingot mold forming a shoulder around the upper edge of the ingot. When the ingot is rolled, a fin sometimes forms due to the presence of the shoulder around the sinkhead which adversely affects the ingot.
SUMMARY OF THE INVENTION
The hot top of this invention provides at the top of an ingot formed in a big end-up type mold a sinkhead formed as a continuation of the sidewalls of the ingot thereby eliminating the shoulder and extending the ingot into the hot top. More particularly, the hot top is superimposed on the top of the ingot mold in a recess provided around the opening at the top of the mold. The juncture between the top top and the ingot mold is sealed by a compressible gasket provided on the hot top. The hot top can be formed as a single use, one piece structure or as a metal casing having a single use liner insert unit. Assembling of the hot top on the mold is simplified by securing the gasket to the single use structure or the panels prior to assembling the hot top on the casing. The location of the gasket at the junction between the hot top and the ingot mold assures the formation of a seal each time a hot top is placed on the ingot mold.
Other objects and advantages of this invention will become apparent from the following description when read in connection with the accompanying drawings.
BREIF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevation view partly broken away showing the insert liner unit positioned within the casing.
FIG. 2 is a view of a liner insert unit laid out flat;
FIG. 3 is a view of an enlarged cross section of a portion of the insert unit showing one form of the gasket attached to the bottom edge of the liner unit;
FIG. 4 is a view of an enlarged cross section of a portion of the unit showing another form of the gasket secured to the bottom edge of the liner by a staple;
FIG. 5 is a view of an enlarged cross section of a portion of the insert unit showing another form of the gasket positioned in a recess provided along the bottom edge of the liner;
FIG. 6 is a side view in section of a portion of the hot top showing the location of the spring clip;
FIG. 7 is a top view of a portion of the hot top showing the clip overlapping the panel insert unit;
FIG. 8 is an elevation view partly broken away showing a single use hot top structure superimposed on the hot top; and
FIG. 9 is an enlarged, cross sectional view of a portion of the hot top showing the position of the gasket in the junction between the hot top and the ingot mold.
DESCRIPTION OF THE INVENTION
Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structure.
One form of the hot top 10 of this invention is shown in FIG. 1 superimposed on the top surface 12 of an ingot mold 14 having sidewalls 16 forming a central cavity 18. The hot top 10 forms a continuation of the cavity 18 in the ingot mold 14 to form a sinkhead at the top of an ingot poured into the mold 14. The hot top 10 is accurately located at the top of the ingot mold by means of an annular recess or groove 20 provided in the top surface 12 around the cavity 18. The hot top is aligned in the groove by means of the upwardly and outwardly tapered wall 21.
The hot top 10 includes a metal casing 22 having an upper surface 24 a lower surface 26 and inner wall surfaces 28 forming a central opening 30. An inwardly projecting flange or canopy 32 is provided around the upper end of the casing 22. The lower portion of the casing 22 is beveled at 23 for mating engagement with the tapered surface 21 around the groove 20. Lifting lugs 34 and turning lugs 36 are provided on the outside surfaces of the casing 22. A number of apertures 25 are provided around the lower portion of the casing. The apertures 25 terminate inwardly in slot 27 provided on the inside surface of the casing 22.
The hot top 10 is insulated by means of a liner insert unit 38 positioned on the inside surfaces 28 of the casing 22. The unit 38 is formed from a plurality of heat destructible panels 40 having beveled edges 42, a top edge 44, a bottom edge 46 and an inner surface 48. The panels 40 are formed from a refractory material bonded by a heat destructible binder as described in U. S. Pat. No. 3,437,308, issued Apr. 8, 1969, with an insulating fiberboard insert as described in application Ser. No. 455,383, filed May 13, 1965 or formed from a fibrous refractory material bonded by a heat destructible binder as described in the co-pending application Ser. No. 843,580, filed July 22, 1969, entitled "Insulating Board" (all three applications commonly owned by the assignee of the present application).
The panels 40 can be inserted individually and wedged tightly into the hot top casing 22 or the panels 40 can be inserted as a single unit. In this regard, the panels 40 are interconnected by means of a flexible band or strip 50 formed from a plastic mesh such as Nylon as shown in the co-pending application Serial No. 843,584 or a material such as wire, rope, paper, cardboard or cloth. The panels 40 are spaced on the strip 50 so that they can be folded to form the hollow hot top insert unit 38 and inserted into the hot top casing 22. The panels 40 are wedged tightly into the casing to form a tight seal between the beveled edges 42 of adjacent panels 40. The panels 40 are inserted into the casing far enough for the top edge 44 to engage the flange 32. The panels 40 have a length substantially equal to the distance from the flange 32 to the bottom surface 26 of the casing 22. The inside surface 48 of the panels 40 should be aligned with the inside surface 28 of the ingot mold 14, as seen in FIG. 1, to eliminate the shoulder between the sinkhead and the ingot formed in the mold. The panels should form a continuation of the wall surfaces of the ingot mold and may be straight or tapered depending on the contour of the mold walls.
In accordance with the invention, means are provided for sealing the junction between the bottom edge 46 of the panels 40 and the top surface 12 of the ingot mold. Such means is in the form of a compressible plastic gasket 52 which is formed of a heat destructible material capable of initially withstanding the heat of the molten metal and deteriorating or burning slowly after exposure to the heat of the molten metal. This material must be capable of burning without gasification so that no explosive reaction is created on destruction of the seal. This material can take various forms, however clay bonded by an inexpensive petroleum oil and including fillers such as asbestos, sand, vermiculite or graphite is generally used. A preferred composition is as follows:
Preferred Example Operable Range percent by weight percent by weight Steam refined cylinder oil (or petroleum oil) 30 20-40 Wetting agents 2 0.5-5.0 Limestone 8 0-50 Clay 33 0-40 Asbestos fiber 27 5-40
The gasket 52 is attached to the bottom edge 46 of the panels 40 so that the gasket 52 forms an integral part of the insert liner unit 38. Various means can be used to attach the gasket 52 to the panels as seen in FIGS. 3, 4 and 5. Referring to FIG. 3, the gasket is shown as a strip 54 positioned on the bottom edge 46 of the panel 40 and secured thereto by means of a combustible wrapper 56 in the form of a sheet of brown paper which is wrapped around the gasket and secured to the sidewalls of the panel 40 by an appropriate adhesive or pressure sensitive adhesive. The paper is used to protect the gasket 54 in shipment and is sufficiently flexible to allow the gasket 54 to be compressed between the panel 40 and the top surface 12 of the ingot mold. The paper 54 will also burn away quickly without any adverse effect on the ingot. The gasket can also be extruded into the groove 20 prior to placing the hot top on the ingot mold to form the seal.
In FIG. 4 the gasket is shown in the form of a strip of material 56 which is completely enclosed by means of a combustible wrapper 58, such as brown paper, cardboard or a plastic film. This form of the gasket can be extruded into the wrapper 50 and tacked along the bottom edge 46 of the panels 40 by means of a number of staples 60. This form of the gasket can be handled easily without exposure to any foreign objects.
In FIG. 5, the gasket is in the form of a bead 62 nested in a groove 64 provided along the outer side of the bottom edge 46 of the panel. A strip of paper 66 is wrapped around the bead 62 and secured to the sidewalls of the panel 40. In all three modifications of the gasket shown in the drawings, the gasket may be attached as an integral part of each of the panels 40 or it may be attached as a single gasket 56 which extends across the entire bottom of the panel insert unit 38 as shown in FIG. 2.
Means are provided for retaining the panel insert unit 38 in the casing 22 while the hot top is being transported and positioned in the groove 20 on the ingot mold 14. Such means is in the form of an internal spring clip 70 provided on the inner surface of the casing 22 and overlapping the bottom of the panels 40. The spring clip 70 is bent at a right angle to form a first or long leg 72 and a second or short leg 74. The end of leg 74 is bent to form a first hook 76 and the end of the long leg 72 is bent to form a second hook 80. The clip 70 is formed from a spring wire material.
As seen in FIG. 6, the clip 70 is mounted on the casing by inserting the hook 76 on the end of short leg 74 into a clip bushing 78 provided in the apertures 25 in the casing 22 with the short leg 74 aligned in one of the slots 27. The long leg 72 initially extends outwardly over the bottom surface 26 of the casing 22 to provide clearance for a panel insert unit 38. After the panel insert unit 38 has been positioned in the casing 22 as seen in FIG. 7, the long leg 72 of the clip 70 is rotated inwardly about the leg 74 until the hook 80 is in a position to engage the inside surface of the panels 40. The short leg 74 is prevented from rotating with the long leg 72 by the engagement of the first hook 76 with the clip bushing 78. When the leg 74 is released, the inherent bias of the spring clip material will snap the hook 80 in abutting engagement with the inside surface of the panels 40.
In the embodiment of the invention shown in FIG. 8, a hot top 90 is shown which is a one piece formed structure made of a refractory material bonded by a heat destructible binder. The structure can be formed from any of the materials as described above for the panels of the insert unit as well as limestone. A disposable type hot top is thereby provided which can be quickly and easily stripped from the ingot.
In this regard, the hot top 90 is shown superimposed on a mold 92 having a central cavity 93 defined by inner walls 94 and a top 95 having recess 96 around the upper end of the cavity 93. The outer vertical wall 97 of the recess tapers outwardly to aid in locating the hot top 90 on the mold.
The hot top 90 includes a central opening 98 formed by inner walls 99 and has a flange 100 on the bottom 101 around the opening 98. The hot top is aligned on the ingot mold by means of the flange 100. In this regard, the flange 100 includes a beveled edge 102 which is tapered to matingly engage the tapered walls 97 on the top of the ingot mold. When the hot top 90 is placed on the ingot mold, the beveled edges 102 on the flange 100 will act to cam the hot top into alignment with the cavity 93 in the ingot mold.
The ingot to be formed in the ingot mold can be extended into the hot top by means of the inner walls 99. This increases the amount of useable steel, since the ingot can be cropped just below the shrink cavity rather than at the shoulder formed by the earlier insertable type hot tops.
Referring to FIG. 8, it should be noted that the walls 99 form a continuation of the walls 94 of the mold. In a big end up type mold as shown, the walls 99 will taper upwardly and outwardly; however, the walls 99 can taper downwardly and outwardly or straight down depending on the configuration of the walls of the ingot mold.
A small fin can form at the juncture between the hot top and ingot mold. This is prevented by means of a compressible gasket 104 which is secured to the bottom of the flange 100 to seal the juncture. Referring to FIG. 9, the gasket 104 shown is similar to the gasket arrangement shown in FIG. 3. The gasket 104 is extruded onto the flange 100 and covered by a wrapper 106. The gasket 104 could also be in the form shown in FIG. 4 or merely extruded onto the flange 100 of the hot top. The material used to form the gasket 104 is identical to the material described above.
Means can be provided for securing the hot top to the top of the ingot mold to prevent movement of the hot top while teeming molten metal into the mold. Such means is in the form of a spring clip 110 having an upper section 112 positioned to engage the top of the hot top and a lower section 114. A ledge or recess 116 is provided in the side wall of the ingot mold for engagement by the lower section 114 of the clip. It should be noted that the ledge 116 is angled upwardly to assure positive engagement with the clip.
Hot tops are conventionally used to form a sinkhead at the top of an ingot mold. The sinkhead isolates the shrinkage cavity formed on solidification of the ingot in a reduced volume section at the top of the ingot. The sink-head is then cropped from the ingot. These hot tops are commonly referred to as floating-type hot tops and are inserted partially into the opening in the top of the mold. Heat-destructible insulating panels and single-use bottom ring assemblies are used to protect the surfaces of the casing as shown in U.S. Pat. No. 3,437,308. The bottom ring assembly also provides a seal between the hot top and the inside surface of the ingot mold. The sinkhead which is formed with this type of hot top is spaced inwardly from the outside edges of the ingot mold forming a shoulder around the upper edge of the ingot. When the ingot is rolled, a fin sometimes forms due to the presence of the shoulder around the sinkhead which adversely affects the ingot.
SUMMARY OF THE INVENTION
The hot top of this invention provides at the top of an ingot formed in a big end-up type mold a sinkhead formed as a continuation of the sidewalls of the ingot thereby eliminating the shoulder and extending the ingot into the hot top. More particularly, the hot top is superimposed on the top of the ingot mold in a recess provided around the opening at the top of the mold. The juncture between the top top and the ingot mold is sealed by a compressible gasket provided on the hot top. The hot top can be formed as a single use, one piece structure or as a metal casing having a single use liner insert unit. Assembling of the hot top on the mold is simplified by securing the gasket to the single use structure or the panels prior to assembling the hot top on the casing. The location of the gasket at the junction between the hot top and the ingot mold assures the formation of a seal each time a hot top is placed on the ingot mold.
Other objects and advantages of this invention will become apparent from the following description when read in connection with the accompanying drawings.
BREIF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevation view partly broken away showing the insert liner unit positioned within the casing.
FIG. 2 is a view of a liner insert unit laid out flat;
FIG. 3 is a view of an enlarged cross section of a portion of the insert unit showing one form of the gasket attached to the bottom edge of the liner unit;
FIG. 4 is a view of an enlarged cross section of a portion of the unit showing another form of the gasket secured to the bottom edge of the liner by a staple;
FIG. 5 is a view of an enlarged cross section of a portion of the insert unit showing another form of the gasket positioned in a recess provided along the bottom edge of the liner;
FIG. 6 is a side view in section of a portion of the hot top showing the location of the spring clip;
FIG. 7 is a top view of a portion of the hot top showing the clip overlapping the panel insert unit;
FIG. 8 is an elevation view partly broken away showing a single use hot top structure superimposed on the hot top; and
FIG. 9 is an enlarged, cross sectional view of a portion of the hot top showing the position of the gasket in the junction between the hot top and the ingot mold.
DESCRIPTION OF THE INVENTION
Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structure.
One form of the hot top 10 of this invention is shown in FIG. 1 superimposed on the top surface 12 of an ingot mold 14 having sidewalls 16 forming a central cavity 18. The hot top 10 forms a continuation of the cavity 18 in the ingot mold 14 to form a sinkhead at the top of an ingot poured into the mold 14. The hot top 10 is accurately located at the top of the ingot mold by means of an annular recess or groove 20 provided in the top surface 12 around the cavity 18. The hot top is aligned in the groove by means of the upwardly and outwardly tapered wall 21.
The hot top 10 includes a metal casing 22 having an upper surface 24 a lower surface 26 and inner wall surfaces 28 forming a central opening 30. An inwardly projecting flange or canopy 32 is provided around the upper end of the casing 22. The lower portion of the casing 22 is beveled at 23 for mating engagement with the tapered surface 21 around the groove 20. Lifting lugs 34 and turning lugs 36 are provided on the outside surfaces of the casing 22. A number of apertures 25 are provided around the lower portion of the casing. The apertures 25 terminate inwardly in slot 27 provided on the inside surface of the casing 22.
The hot top 10 is insulated by means of a liner insert unit 38 positioned on the inside surfaces 28 of the casing 22. The unit 38 is formed from a plurality of heat destructible panels 40 having beveled edges 42, a top edge 44, a bottom edge 46 and an inner surface 48. The panels 40 are formed from a refractory material bonded by a heat destructible binder as described in U. S. Pat. No. 3,437,308, issued Apr. 8, 1969, with an insulating fiberboard insert as described in application Ser. No. 455,383, filed May 13, 1965 or formed from a fibrous refractory material bonded by a heat destructible binder as described in the co-pending application Ser. No. 843,580, filed July 22, 1969, entitled "Insulating Board" (all three applications commonly owned by the assignee of the present application).
The panels 40 can be inserted individually and wedged tightly into the hot top casing 22 or the panels 40 can be inserted as a single unit. In this regard, the panels 40 are interconnected by means of a flexible band or strip 50 formed from a plastic mesh such as Nylon as shown in the co-pending application Serial No. 843,584 or a material such as wire, rope, paper, cardboard or cloth. The panels 40 are spaced on the strip 50 so that they can be folded to form the hollow hot top insert unit 38 and inserted into the hot top casing 22. The panels 40 are wedged tightly into the casing to form a tight seal between the beveled edges 42 of adjacent panels 40. The panels 40 are inserted into the casing far enough for the top edge 44 to engage the flange 32. The panels 40 have a length substantially equal to the distance from the flange 32 to the bottom surface 26 of the casing 22. The inside surface 48 of the panels 40 should be aligned with the inside surface 28 of the ingot mold 14, as seen in FIG. 1, to eliminate the shoulder between the sinkhead and the ingot formed in the mold. The panels should form a continuation of the wall surfaces of the ingot mold and may be straight or tapered depending on the contour of the mold walls.
In accordance with the invention, means are provided for sealing the junction between the bottom edge 46 of the panels 40 and the top surface 12 of the ingot mold. Such means is in the form of a compressible plastic gasket 52 which is formed of a heat destructible material capable of initially withstanding the heat of the molten metal and deteriorating or burning slowly after exposure to the heat of the molten metal. This material must be capable of burning without gasification so that no explosive reaction is created on destruction of the seal. This material can take various forms, however clay bonded by an inexpensive petroleum oil and including fillers such as asbestos, sand, vermiculite or graphite is generally used. A preferred composition is as follows:
Preferred Example Operable Range percent by weight percent by weight Steam refined cylinder oil (or petroleum oil) 30 20-40 Wetting agents 2 0.5-5.0 Limestone 8 0-50 Clay 33 0-40 Asbestos fiber 27 5-40
The gasket 52 is attached to the bottom edge 46 of the panels 40 so that the gasket 52 forms an integral part of the insert liner unit 38. Various means can be used to attach the gasket 52 to the panels as seen in FIGS. 3, 4 and 5. Referring to FIG. 3, the gasket is shown as a strip 54 positioned on the bottom edge 46 of the panel 40 and secured thereto by means of a combustible wrapper 56 in the form of a sheet of brown paper which is wrapped around the gasket and secured to the sidewalls of the panel 40 by an appropriate adhesive or pressure sensitive adhesive. The paper is used to protect the gasket 54 in shipment and is sufficiently flexible to allow the gasket 54 to be compressed between the panel 40 and the top surface 12 of the ingot mold. The paper 54 will also burn away quickly without any adverse effect on the ingot. The gasket can also be extruded into the groove 20 prior to placing the hot top on the ingot mold to form the seal.
In FIG. 4 the gasket is shown in the form of a strip of material 56 which is completely enclosed by means of a combustible wrapper 58, such as brown paper, cardboard or a plastic film. This form of the gasket can be extruded into the wrapper 50 and tacked along the bottom edge 46 of the panels 40 by means of a number of staples 60. This form of the gasket can be handled easily without exposure to any foreign objects.
In FIG. 5, the gasket is in the form of a bead 62 nested in a groove 64 provided along the outer side of the bottom edge 46 of the panel. A strip of paper 66 is wrapped around the bead 62 and secured to the sidewalls of the panel 40. In all three modifications of the gasket shown in the drawings, the gasket may be attached as an integral part of each of the panels 40 or it may be attached as a single gasket 56 which extends across the entire bottom of the panel insert unit 38 as shown in FIG. 2.
Means are provided for retaining the panel insert unit 38 in the casing 22 while the hot top is being transported and positioned in the groove 20 on the ingot mold 14. Such means is in the form of an internal spring clip 70 provided on the inner surface of the casing 22 and overlapping the bottom of the panels 40. The spring clip 70 is bent at a right angle to form a first or long leg 72 and a second or short leg 74. The end of leg 74 is bent to form a first hook 76 and the end of the long leg 72 is bent to form a second hook 80. The clip 70 is formed from a spring wire material.
As seen in FIG. 6, the clip 70 is mounted on the casing by inserting the hook 76 on the end of short leg 74 into a clip bushing 78 provided in the apertures 25 in the casing 22 with the short leg 74 aligned in one of the slots 27. The long leg 72 initially extends outwardly over the bottom surface 26 of the casing 22 to provide clearance for a panel insert unit 38. After the panel insert unit 38 has been positioned in the casing 22 as seen in FIG. 7, the long leg 72 of the clip 70 is rotated inwardly about the leg 74 until the hook 80 is in a position to engage the inside surface of the panels 40. The short leg 74 is prevented from rotating with the long leg 72 by the engagement of the first hook 76 with the clip bushing 78. When the leg 74 is released, the inherent bias of the spring clip material will snap the hook 80 in abutting engagement with the inside surface of the panels 40.
In the embodiment of the invention shown in FIG. 8, a hot top 90 is shown which is a one piece formed structure made of a refractory material bonded by a heat destructible binder. The structure can be formed from any of the materials as described above for the panels of the insert unit as well as limestone. A disposable type hot top is thereby provided which can be quickly and easily stripped from the ingot.
In this regard, the hot top 90 is shown superimposed on a mold 92 having a central cavity 93 defined by inner walls 94 and a top 95 having recess 96 around the upper end of the cavity 93. The outer vertical wall 97 of the recess tapers outwardly to aid in locating the hot top 90 on the mold.
The hot top 90 includes a central opening 98 formed by inner walls 99 and has a flange 100 on the bottom 101 around the opening 98. The hot top is aligned on the ingot mold by means of the flange 100. In this regard, the flange 100 includes a beveled edge 102 which is tapered to matingly engage the tapered walls 97 on the top of the ingot mold. When the hot top 90 is placed on the ingot mold, the beveled edges 102 on the flange 100 will act to cam the hot top into alignment with the cavity 93 in the ingot mold.
The ingot to be formed in the ingot mold can be extended into the hot top by means of the inner walls 99. This increases the amount of useable steel, since the ingot can be cropped just below the shrink cavity rather than at the shoulder formed by the earlier insertable type hot tops.
Referring to FIG. 8, it should be noted that the walls 99 form a continuation of the walls 94 of the mold. In a big end up type mold as shown, the walls 99 will taper upwardly and outwardly; however, the walls 99 can taper downwardly and outwardly or straight down depending on the configuration of the walls of the ingot mold.
A small fin can form at the juncture between the hot top and ingot mold. This is prevented by means of a compressible gasket 104 which is secured to the bottom of the flange 100 to seal the juncture. Referring to FIG. 9, the gasket 104 shown is similar to the gasket arrangement shown in FIG. 3. The gasket 104 is extruded onto the flange 100 and covered by a wrapper 106. The gasket 104 could also be in the form shown in FIG. 4 or merely extruded onto the flange 100 of the hot top. The material used to form the gasket 104 is identical to the material described above.
Means can be provided for securing the hot top to the top of the ingot mold to prevent movement of the hot top while teeming molten metal into the mold. Such means is in the form of a spring clip 110 having an upper section 112 positioned to engage the top of the hot top and a lower section 114. A ledge or recess 116 is provided in the side wall of the ingot mold for engagement by the lower section 114 of the clip. It should be noted that the ledge 116 is angled upwardly to assure positive engagement with the clip.