INGOT-MOLDS COMPRISING INGOT INSULATING MEANS
United States Patent 3752435
The invention relates to ingot-molds which are intended to be stripped from ingots very shortly after filling. The ingot-mold comprises ingot insulating means comprising a heat-insulating lining fixed along the internal surface of the mold near the upper portion thereof; the lining has a bottom portion applied without clearance against said internal surface and above said bottom portion, a recessed portion which provides a peripheral gap between said lining and said internal surface; the lining is further provided with lateral openings establishing a communication between said peripheral gap and the space inside the lining and with vents establishing a communication between the top portion of said peripheral gap and the atmosphere.
US Patent References:
Ingot casting mold
Gombosh - October 1952 - 2612667
Hot tops, feeders or sinking head boxes
Vallak - February 1959 - 2873492
Hot top for ingot mold
Ednell et al. - April 1965 - 3178783
Ingot casting mold
Gombosh - October 1952 - 2612667
Hot tops, feeders or sinking head boxes
Vallak - February 1959 - 2873492
Hot top for ingot mold
Ednell et al. - April 1965 - 3178783
Application Number:
05/239118
Publication Date:
08/14/1973
Filing Date:
03/29/1972
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
249/197
International Classes:
B22D7/10; B22D7/00; B22D7/10
Field of Search:
249/106,197-201
Primary Examiner:
Baldwin, Robert D.
Parent Case Data:
This application is a division of my copending application Ser. No. 40,187, now U.S. Pat. No. 3,672,433, June 27, 1972.
Claims:
I claim
1. An ingot mold having a heat-insulating lining secured to the internal surface thereof, said lining having a lower portion applied with zero clearance against said internal surface along a contact zone impervious to the cast metal, an upper portion applied along at least part of its periphery against said internal surface and having a top edge located at a higher level than the level reached in use by the molten metal, and an intermediate portion having an external surface recessed with respect to said upper and lower portions thereby providing a narrow peripheral gap of substantially constant thickness extending between said lining and said internal surface from said lower to said upper portion of the liniuG and communicating with the atmosphere by means of at least one vent provided through the upper portion of the linIng, there being at least one lateral opening through said intermediate portion of the lining, said lateral opening being spaced a substantial distance above said contact zone, whereby when molten metal is cast into the ingot mold, molten metal flows through said lateral opening into said lateral gap and quickly solidifies within said lateral gap while air and gases pass out of said gap to the atmosphere through said vent thereby providing a metallic belt adapted to retain said lining against the ingot when stripping of the latter takes place.
2. An ingot mold as claimed in claim 1, the top edge of the lining being located at a higher level than the top end face of the ingot mold.
3. An ingot mold as claimed in claim 2, the upper portion of the lining comprising a projection which is adapted to bear on the top end face of the ingot mold.
4. An ingot mold as claimed in claim 2, the upper portiOn of the lining comprising an inner wall which forms an outward extension of said intermediate portion and an outer wall which is in contact with the internal surface of said ingot mold, said inner wall and said outer wall being spaced from one another and being rigidly fixed to each other by means of connecting members.
5. An ingot mold as claimed in claim 1, said intermediate portion having at two different levels at least one lateral opening establishing at each level a communication between the peripheral gap and the space inside the lining.
1. An ingot mold having a heat-insulating lining secured to the internal surface thereof, said lining having a lower portion applied with zero clearance against said internal surface along a contact zone impervious to the cast metal, an upper portion applied along at least part of its periphery against said internal surface and having a top edge located at a higher level than the level reached in use by the molten metal, and an intermediate portion having an external surface recessed with respect to said upper and lower portions thereby providing a narrow peripheral gap of substantially constant thickness extending between said lining and said internal surface from said lower to said upper portion of the liniuG and communicating with the atmosphere by means of at least one vent provided through the upper portion of the linIng, there being at least one lateral opening through said intermediate portion of the lining, said lateral opening being spaced a substantial distance above said contact zone, whereby when molten metal is cast into the ingot mold, molten metal flows through said lateral opening into said lateral gap and quickly solidifies within said lateral gap while air and gases pass out of said gap to the atmosphere through said vent thereby providing a metallic belt adapted to retain said lining against the ingot when stripping of the latter takes place.
2. An ingot mold as claimed in claim 1, the top edge of the lining being located at a higher level than the top end face of the ingot mold.
3. An ingot mold as claimed in claim 2, the upper portion of the lining comprising a projection which is adapted to bear on the top end face of the ingot mold.
4. An ingot mold as claimed in claim 2, the upper portiOn of the lining comprising an inner wall which forms an outward extension of said intermediate portion and an outer wall which is in contact with the internal surface of said ingot mold, said inner wall and said outer wall being spaced from one another and being rigidly fixed to each other by means of connecting members.
5. An ingot mold as claimed in claim 1, said intermediate portion having at two different levels at least one lateral opening establishing at each level a communication between the peripheral gap and the space inside the lining.
Description:
This invention relates to ingot molds or casting molds of similar types which are intended to be stripped from ingots without any stationary period, that is to say in which stripping is performed very shortly after filling of the molds.
It is known practice to make use of ingot insulating means consisting of heat-insulating and/or exothermic lining which is placed prior to casting of a metal on the internal surface of an ingot mold and at the top of said surface or within the interior of a raised top section or so-called hot top. Said lining remains bonded to the ingot at the moment of stripping of the mold and is intended to maintain the top part of the cast metal bath in the liquid state during solidification for a sufficient period of time to ensure that the pipes or cavities formed in the ingot as a result of shrinkage of this latter are filled by the metal which has remained in the liquid state at the top portion of the mold.
In the case of known means, it is necessary after filling of ingot molds to hold these latter in a stationary position in the casting area until the metal contained therein has solidified to a sufficient extent te ensure that stripping and displacement of stripped ingots can take place without any attendant hazards. Such hazards are related to the quality of the ingot or casting and above all to the safety of persons who are in charge of operations involved in stripping and removal from the casting area and who are exposed to projections of metal which has not yet solidified.
In practice, in the case of ingots whose weight varies between 2 tons and 100 tons, the time during which said ingots remain stationary and which is a function of many factors is usually between 2 and 6 hours. Up to the present time, it has never proved possible to reduce this delay to a period of less than 1 hour in spite of precautionary measures taken during the casting operation. This has resulted in considerable capital expenditure, not only by reason of the "standing" of ingot molds (or, in other words, of keeping them in a stationary position) but also as a result of the heat which is dissipated during standing and which must be restored by means of heating furnaces such as ingot reheating furnaces, hereafter called pits.
This invention is intended to reduce standing times to a minimum as well as corresponding losses of heat while obtaining better behaviour of ingots during solidification of these latter.
In accordance with the invention the ingot mold having a raised top section adapted thereto when necessary comprises ingot insulating means, wherein said means comprises a heat-insulating lining fixed along the internal surface of said ingot mold, extending within said top section when the latter is used, near the upper portion of said internal surface, wherein said lining has a bottom portion applied without clearance against said internal surface and, above said bottom portion, a recessed portion which provides a peripheral gap between said lining and said internal surface and wherein said lining is provided with at least one lateral opening adapted to establish a communication between said peripheral gap and the space inside the lining and with at least one vent adapted to establish a communication between the top portion of said peripheral gap and the atmosphere.
After penetrating through the lateral openings into the peripheral gap and filling the same progressively while air and gases contained therein are driven out through the vents, the molten metal solidifies very quickly in contact with the internal wall of the ingot mold and/or top section in order to form around the lining a band which ensures lateral protection of the lining, together with the ingot, at the moment of stripping and during the following operations.
The heat-insulating lining is preferably given an exothermic character.
In a preferred embodiment of the ingot mold according to the invention, the bottom portion of the lining extends over a small part of the total height of said lining from the bottom edge thereof and said lining further comprises a top flange, disposed above the recessed portion of the lining, said flange extending over at least part Of the periphery of said lining.
In an advantageous embodiment, the ingot insulating means comprises a prefabricated cover and means such as anchoring rods for bonding said cover to the ingot during solidification thereof.
Therefore stripping and transporting of the ingot away from the location provided for casting of ingot molds are carried out as soon as the still-unsolidified central portIon of the ingot is completely isolated from the exterior, especially under the protection action of the cover and of the metal which has solidified within the peripheral gap after filling of said gap.
The combination of means consisting in protecting the top portion of the ingot by surrounding said casting both with a peripheral band of metal and with a cover which is securely attached to the ingot therefore provides a complete solution to the problem which consists in substantially avoiding any standing of ingots after filling of the molds without entailing any danger of projections of liquid metal during displacement of the ingots.
Further properties of the invention will become apparent from the description given hereinafter, reference being made to the accompanying drawings which are given by way of non-limitative example and show a number of different forms of execution of the invention, and in which :
FIG. 1 is a view in elevation and in cross-section taken along line I--I of FIG. 2 and showing a first form of construction of the lining which is placed in the top portion of an ingot mold;
FIG. 2 is a corresponding plan view taken in cross-section along line II--II of FIG. 1 ;
FIG. 3 is a partial view derived from FIG. 1 but drawn on a larger scale after addition of a prefabricated cover to the lining ;
FIG. 4 is a view in elevation and in cross-section taken along line IV--IV of FIG. 5 and showing a second form of construction of the lining ;
FIG. 5 is a corresponding plan view taken in cross-section along line V--V of FIG. 4 ;
FIG. 6 is a view in elevation and in cross-section taken along line VI--VI of FIG. 7 and showing a third form of construction of the lining ;
FIG. 7 is a corresponding plan view.
Referring now to FIGS. 1 and 2 of the accompanying drawings, there is shown an ingot mold A having a substantially square horizontal cross-section with rounded corners. A lining which is constructed in accordance with a first form of execution of the invention and designated by the general reference B is placed within the interior of the ingot mold. Said lining, the top end face 2 of which is located at a lower level than that of the tOp end face 1 of the ingot mold, is constituted by four plates which are symmetrical in pairs, namely the plates 4a and 4c on the one hand and the plates 4b and 4d on the other hand. These plates are in contact with each other along edges 5 and 5a, said edges being inclined symmetrically with respect to a vertical plane which passes through the longitudinal axis Y--Y of the ingot mold A ; in addition, the edges 5 and 5a are oblique with respect to the walls of the ingot mold. By virtue of this arrangement, the plates 4b and 4d behave with respect to the plates 4a and 4c in much the same manner as wedges, the downward displacement of which makes it possible to obtain a very tight fit of the lining within the interior of the ingot mold.
It should be pointed out that the ingot mold A as illustrated in the figures has an internal wall 3 whose generator-lines are parallel to the longitudinal axis Y--Y. In general, in order to facilitate stripping of the mold from the ingot, said generator-lines are inclined at an angle which is referred-to as a "draw-taper" and accordingly converge either towards the top or towards the bottom. But this arrangement does not have any incidence on the invention which is equally applicable to the case in which the generator-lines converge towards the top and to the case in which they converge towards the bottom. It is by reason of this lack of distinction that the ingot molds are shown in the figures without any draw-taper.
Consideration being now given to a vertical cross-section of the lining B, it is seen from FIG. 1 that said lining is provided from the bottom upwards with three zones, namely a bottom zone having an external wall 6 which is applied in intimate contact with the internal wall 3 of the ingot mold A and with out clearance around its entire periphery ; a central zone whose external wall 7 is recessed relative to the wall 6 so that a peripheral gap C is accordingly formed between said wall 7 and the internal wall 3 of the ingot mold ; a top zone whose external wall 8 is in contact with the internal wall 3 of the ingot mold only over a portion of its periphery, vents 10 being formed at intervals between the wall 8 and the wall 3. The vents 10 are four in number in the example shown in FIG. 2 and serve to connect the peripheral gap C to the atmosphere. In addition, the central zone of the lining is traversed by lateral openings 9 which provide a communication between the peripheral gap C and the space formed within the interior of the lining B; said openings 9 are twelve in number in FIG. 2 and have the shape of outwardly inclined ducts, the lower portion of which is located in the external wall 7.
There is also shown in FIG. 1 the molten metal M with which the ingot mold is filled.
In FIG. 3, there is also shown a sheet metal cover 13 which is placed over the molten metal M and is fitted with four anchoring rods, only two rods having been shown in this figure, namely the rods 14 and 14a ; said rods are intended to penetrate into the molten metal M at an oblique angle.
The ingot mold as hereinabove described is utilized as follows :
1. Prior to casting, the assembly which consists of the four plates 4a, 4b, 4c, 4d and forms the lining B is placed on the internal wall 3 of the ingot mold A so that the top end face 2 of said lining is located slightly below the top end face 1 of the ingot mold A. As has been explained earlier, the wedging action resulting from the inclination of the edges 5 and 5a along which the plates 4a, 4b, 4c, 4d are applied in contact with each other ensures on the one hand that the lining B is maintained at a fixed height within the ingot mold A and on the other hand that a contact without clearance is maintained between the external wall 6 of the bottom zone of the lining B and the internal wall 3 of the ingot mold A.
2. The molten metal A is then poured into the ingot mold A and this operation can be carried out at will either "downhill" (from the top of the ingot mold) or "uphill" (from the bottom of the mold). This pouring operation is continued until the free surface of the Molten metal bath reaches the level designated by N--N on the eft-hand side of FIGS. 1 and 3. This level N--N must be located below the top end face 2 of the lining and slightly above the lateral openings 9. The molten metal M penetrates through said lateral openings into the peripheral gap C and fills this latter progressively while driving out the air which is contained therein and which is discharged to the atmosphere through the vents 10 together with the gases which are given off by the molten metal.
3. While shrinkage takes place and a cavity is being formed therefore at the surface of the cast metal bath, the molten metal M begins to solidify in that portion which is in contact with the lining B, namely firstly in the portion which fills the peripheral gap C and which forms a layer of small thickness between the ingot mold A and the lining B ; on the right-hand side of FIGS. 1 and 3, the solidified metal is represented by oblique hatchings whereas the metal which is still in the liquid state is represented by horizontal hatchings.
4. As soon as the mokten metal has reached the level N--N the prefabricated cover 13 is placed in position as rapidly as possible. Said cover becomes attached at its periphery to the metal which is located in the vicinity of the lining B and which beings to solidify, with the result that the cover is rapidly bonded to the ingot. In order to make this bond even more secure, the cover can be fitted with anchoring means such as the rods 14 and 14a which are shown in FIG. 3 and are intended to penetrate to a substantial depth into that portion of the molten metal which first begins to solidfy.
5. Once these operations have been carried out, the metal ingot M can be removed from the mold by the usual means without waiting for the central portion located in the vicinity of the longitudinal axis Y--Y to solidify up to the top. In fact, the metal which has remained in the liquid state is surrounded by the cover 13 after this latter has been securely fixed to the peripheral zone which has already solidified and by the lining B which is in turn securely maintained in contact with the ingot by means of the metallic band produced by the metal which has solidified from the outset within the peripheral gap C. It will then be possible to displace the ingot without entailing the need for any stationary period or standing time after casting and without any risk of consequent danger to operating personnel.
6. After removal from the mold, the ingot is conveyed to the pits in which the solidification process is completed under the most advantageous conditions of cost and quality by eliminating standing time and resultant heat losses. If this transfer to the ingot pits is not carried out immediately for any reason, the ingots can in any case be brought to an intermediate waiting station so that the casting pit or any other working site employed for filling ingot molds may thus be freed for the following operation.
In FIGS. 4 and 5, there is shown a lining B 1 which is constructed according to a second form of execution of the invention. In this example, the top edge or end face 2 of the lining is located at a higher level than the top end face 1 of the ingot mold A, which makes it possible to fill said mold with the metal M up to the level of said end face 1. In addition, the plates 11a, 11b, 11c, 11d which constitute the four side walls of the lining are provided with shouldered portions 12a, 12b, 12c, 12d which bear on the top end face 1 of the ingot mold.
In this second form of execution, the plates are provided with lateral openings 9 and vents 10 as in the first form of construction. However, the lateral edges of said plates are not juxtaposed and are separated by four wedge-shaped members 16a, 16b, 16c, 16d which are in contact with the rounded corners of the ingot mold A and the downward displacement of which serves to form a tight joint between the internal wall 3 of the ingot mold and the external wall 6 of the bottom portion of the lining B 1 . The wedge-shaped members 16a, 16b, 16c, 16d are provided at mid-height in the same manner as the plates 11a, 11b1 11c, 11d with a central zone, the external wall of which is recessed with respect to the wall of the bottom zone and is traversed by lateral openings 9 for the passage of liquid metal. The metallic band which is formed around the lining B 1 as a result of solidification of the metal within the peripheral gap C is therefore continuous as in the first form of execution of the invention.
FIGS. 6 and 7 show a lining B 2 which is constructed in accordance with a third form of execution of the invention. As in the previous case, the top end face 2 of the lining is located at a higher level than the top end face 1 of the ingot mold A. But in this example, the lining B 2 is in fact formed in one piece or at least the top portion of said lining has a wall in which there are no joints. By virtue of this arrangement, the liquid metal can be poured up to a level N 2 --N 2 which is higher than that of the top end face of the ingot mold. This permits a further increase in the quantity of metal which can be oast into the same ingot mold A as in the previous embodiment whilst the lining B 2 constitutes at the same time a hot top or raised top section of the ingot mold.
There can again be seen in the lining B 2 the same lateral openings 9 and the same vents 10 as in the linings B and B 1 . However, the top portion of the lining has a double wall, namely : an inner wall 17 which forms an upward extension of the central zone and an outer wall 18 in the form of a sleeve which is in contact with the internal wall 3 of the ingot mold A. The walls 17 and 18 are joined together at the level of the top end face of the lining by means of a ring-shaped connecting member 19 in which are formed the vents 10. The ring 19 can be made up of a number of elements which are joined to the walls 17 and 18 in known manner ; however, said ring can also be integral with said walls so as to form a single-unit assembly.
It is apparent that the invention is not limited to the embodiments herein described and that many alternative forms may accordingly be contemplated. However, the following main advantages are again met with in all cases :
1. A higher degree of safety for operating personnel.
2. Shorter periods of standing of ingot molds.
3. Economy of heating in pits.
4. Better quality of ingots.
It is known practice to make use of ingot insulating means consisting of heat-insulating and/or exothermic lining which is placed prior to casting of a metal on the internal surface of an ingot mold and at the top of said surface or within the interior of a raised top section or so-called hot top. Said lining remains bonded to the ingot at the moment of stripping of the mold and is intended to maintain the top part of the cast metal bath in the liquid state during solidification for a sufficient period of time to ensure that the pipes or cavities formed in the ingot as a result of shrinkage of this latter are filled by the metal which has remained in the liquid state at the top portion of the mold.
In the case of known means, it is necessary after filling of ingot molds to hold these latter in a stationary position in the casting area until the metal contained therein has solidified to a sufficient extent te ensure that stripping and displacement of stripped ingots can take place without any attendant hazards. Such hazards are related to the quality of the ingot or casting and above all to the safety of persons who are in charge of operations involved in stripping and removal from the casting area and who are exposed to projections of metal which has not yet solidified.
In practice, in the case of ingots whose weight varies between 2 tons and 100 tons, the time during which said ingots remain stationary and which is a function of many factors is usually between 2 and 6 hours. Up to the present time, it has never proved possible to reduce this delay to a period of less than 1 hour in spite of precautionary measures taken during the casting operation. This has resulted in considerable capital expenditure, not only by reason of the "standing" of ingot molds (or, in other words, of keeping them in a stationary position) but also as a result of the heat which is dissipated during standing and which must be restored by means of heating furnaces such as ingot reheating furnaces, hereafter called pits.
This invention is intended to reduce standing times to a minimum as well as corresponding losses of heat while obtaining better behaviour of ingots during solidification of these latter.
In accordance with the invention the ingot mold having a raised top section adapted thereto when necessary comprises ingot insulating means, wherein said means comprises a heat-insulating lining fixed along the internal surface of said ingot mold, extending within said top section when the latter is used, near the upper portion of said internal surface, wherein said lining has a bottom portion applied without clearance against said internal surface and, above said bottom portion, a recessed portion which provides a peripheral gap between said lining and said internal surface and wherein said lining is provided with at least one lateral opening adapted to establish a communication between said peripheral gap and the space inside the lining and with at least one vent adapted to establish a communication between the top portion of said peripheral gap and the atmosphere.
After penetrating through the lateral openings into the peripheral gap and filling the same progressively while air and gases contained therein are driven out through the vents, the molten metal solidifies very quickly in contact with the internal wall of the ingot mold and/or top section in order to form around the lining a band which ensures lateral protection of the lining, together with the ingot, at the moment of stripping and during the following operations.
The heat-insulating lining is preferably given an exothermic character.
In a preferred embodiment of the ingot mold according to the invention, the bottom portion of the lining extends over a small part of the total height of said lining from the bottom edge thereof and said lining further comprises a top flange, disposed above the recessed portion of the lining, said flange extending over at least part Of the periphery of said lining.
In an advantageous embodiment, the ingot insulating means comprises a prefabricated cover and means such as anchoring rods for bonding said cover to the ingot during solidification thereof.
Therefore stripping and transporting of the ingot away from the location provided for casting of ingot molds are carried out as soon as the still-unsolidified central portIon of the ingot is completely isolated from the exterior, especially under the protection action of the cover and of the metal which has solidified within the peripheral gap after filling of said gap.
The combination of means consisting in protecting the top portion of the ingot by surrounding said casting both with a peripheral band of metal and with a cover which is securely attached to the ingot therefore provides a complete solution to the problem which consists in substantially avoiding any standing of ingots after filling of the molds without entailing any danger of projections of liquid metal during displacement of the ingots.
Further properties of the invention will become apparent from the description given hereinafter, reference being made to the accompanying drawings which are given by way of non-limitative example and show a number of different forms of execution of the invention, and in which :
FIG. 1 is a view in elevation and in cross-section taken along line I--I of FIG. 2 and showing a first form of construction of the lining which is placed in the top portion of an ingot mold;
FIG. 2 is a corresponding plan view taken in cross-section along line II--II of FIG. 1 ;
FIG. 3 is a partial view derived from FIG. 1 but drawn on a larger scale after addition of a prefabricated cover to the lining ;
FIG. 4 is a view in elevation and in cross-section taken along line IV--IV of FIG. 5 and showing a second form of construction of the lining ;
FIG. 5 is a corresponding plan view taken in cross-section along line V--V of FIG. 4 ;
FIG. 6 is a view in elevation and in cross-section taken along line VI--VI of FIG. 7 and showing a third form of construction of the lining ;
FIG. 7 is a corresponding plan view.
Referring now to FIGS. 1 and 2 of the accompanying drawings, there is shown an ingot mold A having a substantially square horizontal cross-section with rounded corners. A lining which is constructed in accordance with a first form of execution of the invention and designated by the general reference B is placed within the interior of the ingot mold. Said lining, the top end face 2 of which is located at a lower level than that of the tOp end face 1 of the ingot mold, is constituted by four plates which are symmetrical in pairs, namely the plates 4a and 4c on the one hand and the plates 4b and 4d on the other hand. These plates are in contact with each other along edges 5 and 5a, said edges being inclined symmetrically with respect to a vertical plane which passes through the longitudinal axis Y--Y of the ingot mold A ; in addition, the edges 5 and 5a are oblique with respect to the walls of the ingot mold. By virtue of this arrangement, the plates 4b and 4d behave with respect to the plates 4a and 4c in much the same manner as wedges, the downward displacement of which makes it possible to obtain a very tight fit of the lining within the interior of the ingot mold.
It should be pointed out that the ingot mold A as illustrated in the figures has an internal wall 3 whose generator-lines are parallel to the longitudinal axis Y--Y. In general, in order to facilitate stripping of the mold from the ingot, said generator-lines are inclined at an angle which is referred-to as a "draw-taper" and accordingly converge either towards the top or towards the bottom. But this arrangement does not have any incidence on the invention which is equally applicable to the case in which the generator-lines converge towards the top and to the case in which they converge towards the bottom. It is by reason of this lack of distinction that the ingot molds are shown in the figures without any draw-taper.
Consideration being now given to a vertical cross-section of the lining B, it is seen from FIG. 1 that said lining is provided from the bottom upwards with three zones, namely a bottom zone having an external wall 6 which is applied in intimate contact with the internal wall 3 of the ingot mold A and with out clearance around its entire periphery ; a central zone whose external wall 7 is recessed relative to the wall 6 so that a peripheral gap C is accordingly formed between said wall 7 and the internal wall 3 of the ingot mold ; a top zone whose external wall 8 is in contact with the internal wall 3 of the ingot mold only over a portion of its periphery, vents 10 being formed at intervals between the wall 8 and the wall 3. The vents 10 are four in number in the example shown in FIG. 2 and serve to connect the peripheral gap C to the atmosphere. In addition, the central zone of the lining is traversed by lateral openings 9 which provide a communication between the peripheral gap C and the space formed within the interior of the lining B; said openings 9 are twelve in number in FIG. 2 and have the shape of outwardly inclined ducts, the lower portion of which is located in the external wall 7.
There is also shown in FIG. 1 the molten metal M with which the ingot mold is filled.
In FIG. 3, there is also shown a sheet metal cover 13 which is placed over the molten metal M and is fitted with four anchoring rods, only two rods having been shown in this figure, namely the rods 14 and 14a ; said rods are intended to penetrate into the molten metal M at an oblique angle.
The ingot mold as hereinabove described is utilized as follows :
1. Prior to casting, the assembly which consists of the four plates 4a, 4b, 4c, 4d and forms the lining B is placed on the internal wall 3 of the ingot mold A so that the top end face 2 of said lining is located slightly below the top end face 1 of the ingot mold A. As has been explained earlier, the wedging action resulting from the inclination of the edges 5 and 5a along which the plates 4a, 4b, 4c, 4d are applied in contact with each other ensures on the one hand that the lining B is maintained at a fixed height within the ingot mold A and on the other hand that a contact without clearance is maintained between the external wall 6 of the bottom zone of the lining B and the internal wall 3 of the ingot mold A.
2. The molten metal A is then poured into the ingot mold A and this operation can be carried out at will either "downhill" (from the top of the ingot mold) or "uphill" (from the bottom of the mold). This pouring operation is continued until the free surface of the Molten metal bath reaches the level designated by N--N on the eft-hand side of FIGS. 1 and 3. This level N--N must be located below the top end face 2 of the lining and slightly above the lateral openings 9. The molten metal M penetrates through said lateral openings into the peripheral gap C and fills this latter progressively while driving out the air which is contained therein and which is discharged to the atmosphere through the vents 10 together with the gases which are given off by the molten metal.
3. While shrinkage takes place and a cavity is being formed therefore at the surface of the cast metal bath, the molten metal M begins to solidify in that portion which is in contact with the lining B, namely firstly in the portion which fills the peripheral gap C and which forms a layer of small thickness between the ingot mold A and the lining B ; on the right-hand side of FIGS. 1 and 3, the solidified metal is represented by oblique hatchings whereas the metal which is still in the liquid state is represented by horizontal hatchings.
4. As soon as the mokten metal has reached the level N--N the prefabricated cover 13 is placed in position as rapidly as possible. Said cover becomes attached at its periphery to the metal which is located in the vicinity of the lining B and which beings to solidify, with the result that the cover is rapidly bonded to the ingot. In order to make this bond even more secure, the cover can be fitted with anchoring means such as the rods 14 and 14a which are shown in FIG. 3 and are intended to penetrate to a substantial depth into that portion of the molten metal which first begins to solidfy.
5. Once these operations have been carried out, the metal ingot M can be removed from the mold by the usual means without waiting for the central portion located in the vicinity of the longitudinal axis Y--Y to solidify up to the top. In fact, the metal which has remained in the liquid state is surrounded by the cover 13 after this latter has been securely fixed to the peripheral zone which has already solidified and by the lining B which is in turn securely maintained in contact with the ingot by means of the metallic band produced by the metal which has solidified from the outset within the peripheral gap C. It will then be possible to displace the ingot without entailing the need for any stationary period or standing time after casting and without any risk of consequent danger to operating personnel.
6. After removal from the mold, the ingot is conveyed to the pits in which the solidification process is completed under the most advantageous conditions of cost and quality by eliminating standing time and resultant heat losses. If this transfer to the ingot pits is not carried out immediately for any reason, the ingots can in any case be brought to an intermediate waiting station so that the casting pit or any other working site employed for filling ingot molds may thus be freed for the following operation.
In FIGS. 4 and 5, there is shown a lining B 1 which is constructed according to a second form of execution of the invention. In this example, the top edge or end face 2 of the lining is located at a higher level than the top end face 1 of the ingot mold A, which makes it possible to fill said mold with the metal M up to the level of said end face 1. In addition, the plates 11a, 11b, 11c, 11d which constitute the four side walls of the lining are provided with shouldered portions 12a, 12b, 12c, 12d which bear on the top end face 1 of the ingot mold.
In this second form of execution, the plates are provided with lateral openings 9 and vents 10 as in the first form of construction. However, the lateral edges of said plates are not juxtaposed and are separated by four wedge-shaped members 16a, 16b, 16c, 16d which are in contact with the rounded corners of the ingot mold A and the downward displacement of which serves to form a tight joint between the internal wall 3 of the ingot mold and the external wall 6 of the bottom portion of the lining B 1 . The wedge-shaped members 16a, 16b, 16c, 16d are provided at mid-height in the same manner as the plates 11a, 11b1 11c, 11d with a central zone, the external wall of which is recessed with respect to the wall of the bottom zone and is traversed by lateral openings 9 for the passage of liquid metal. The metallic band which is formed around the lining B 1 as a result of solidification of the metal within the peripheral gap C is therefore continuous as in the first form of execution of the invention.
FIGS. 6 and 7 show a lining B 2 which is constructed in accordance with a third form of execution of the invention. As in the previous case, the top end face 2 of the lining is located at a higher level than the top end face 1 of the ingot mold A. But in this example, the lining B 2 is in fact formed in one piece or at least the top portion of said lining has a wall in which there are no joints. By virtue of this arrangement, the liquid metal can be poured up to a level N 2 --N 2 which is higher than that of the top end face of the ingot mold. This permits a further increase in the quantity of metal which can be oast into the same ingot mold A as in the previous embodiment whilst the lining B 2 constitutes at the same time a hot top or raised top section of the ingot mold.
There can again be seen in the lining B 2 the same lateral openings 9 and the same vents 10 as in the linings B and B 1 . However, the top portion of the lining has a double wall, namely : an inner wall 17 which forms an upward extension of the central zone and an outer wall 18 in the form of a sleeve which is in contact with the internal wall 3 of the ingot mold A. The walls 17 and 18 are joined together at the level of the top end face of the lining by means of a ring-shaped connecting member 19 in which are formed the vents 10. The ring 19 can be made up of a number of elements which are joined to the walls 17 and 18 in known manner ; however, said ring can also be integral with said walls so as to form a single-unit assembly.
It is apparent that the invention is not limited to the embodiments herein described and that many alternative forms may accordingly be contemplated. However, the following main advantages are again met with in all cases :
1. A higher degree of safety for operating personnel.
2. Shorter periods of standing of ingot molds.
3. Economy of heating in pits.
4. Better quality of ingots.