CA2230044A1 - Continuous casting method and apparatus therefor - Google Patents
Continuous casting method and apparatus therefor Download PDFInfo
- Publication number
- CA2230044A1 CA2230044A1 CA 2230044 CA2230044A CA2230044A1 CA 2230044 A1 CA2230044 A1 CA 2230044A1 CA 2230044 CA2230044 CA 2230044 CA 2230044 A CA2230044 A CA 2230044A CA 2230044 A1 CA2230044 A1 CA 2230044A1
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- tundish
- mould
- tundishes
- flow
- tap hole
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/10—Supplying or treating molten metal
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- Mechanical Engineering (AREA)
- Continuous Casting (AREA)
Abstract
The invention relates to a method and apparatus for continuous casting of metal, comprising pouring the molten metal from a tundish into a mould through a tap hole in a base wall of the tundish, and wherein first and second tundishes and associated corresponding first and second nozzle means, are used to enable the flow of molten metal to be continuous or nearly continuous, such that when one of the first tundish is required to be changed it is moved into a changeover position, wherein both the first and second tundishes are in positionover the mould so that metal may flow from both tundishes simultaneously into the mould, with the nozzle means immersed in the molten metal in the mould.
The combined flow from the first and second tundishes is approximately equal to the required full flow from one tundish. The second tundish is moved with the first tundish, in the same direction such that a second tap hole is over themould so that molten metal flows from the second tundish into the mould. The flow from the first and second tundishes is regulated so that the combined flow rate does not exceed a prescribed rate.
The combined flow from the first and second tundishes is approximately equal to the required full flow from one tundish. The second tundish is moved with the first tundish, in the same direction such that a second tap hole is over themould so that molten metal flows from the second tundish into the mould. The flow from the first and second tundishes is regulated so that the combined flow rate does not exceed a prescribed rate.
Description
CONTINUOUS CASTlNG METHOD AND APPARATUS THEREFOR
5 The present invention relates to a continuous casting method and apparatus therefore including a new tundish design for ensuring the continuous casting method may be continued for long casting runs with minimised interruption.
ln td1e continuous casting of metals and in particular steel it is advantageous to 10 extend the length of the cast. This provides two main advantages. Firstly, itm~ximi~es the duration of the steady state conditions when the best product quality is achieved and this in turn reduces the amount of scrap steel produced typically from the begim1ing and end portions of a casting run which are not of sufficiently quality and it also improves the overall quality of the finished 15 product. Secondly production levels are m~ximised and the existing plant and equipment is able to be utilised to a greater extent which improves the return on investment.
There is an additional advalltage in that the length of the cast can be optimised 20 with the duration of the available life from the wear components in the casting process which can be changed at the end of each cast. Thus if the cast is long enough the full life of the main wear components can be used which reduces downtime and the cost of replacement of the wear parts.
25 Duril1g the casting process metal is poured thlough a tap hole in a vessel and this vessel is typically in the form of a tundish. ln order to extend the desired casting time it is necessary to replace the tundish a nurmber of times after each time its life is expended. In particular for the casting of fenous metals such as steel, the high temperature chemical aggression and physical erosion of the 30 refractory material of the tundish permits the tundish to run continuously for only short periods before they have to be exchanged cleaned of slag and relined. Thus it is necessary to changeover the tundish a number of times in order to continuously cast the steel over a long period. Such tundish changes are sometimes known as flying tundish changes.
A known method of ch~n,Qing over tundishes and a tundish used is shown in figures 1 to 3. ln figure 1 the first tundish is in the casting position over the mould and the second tundish 2 is in a "waiting to cast" position to one side.
When it is time to change the first tundish 1, the first tundish 1 remains in the 5 casting position until all the metal in the first tundish 1 is poured into the mould 5. The tap hole is then closed and the first tundish 1 is moved sideways to a parking position as shown in figure 2. Simultaneously the second tundish is moved sideways from a pre-fill position into the casting position over the mould 5. When it is in the desired casting position, as shown in figure 3, it is10 filled with metal and its tap hole is opened and casting can recommence.
This conventional tundisll changeover method is acceptable for standard conventional continuous casting runs. In such runs a strand which is essentially parallel is formed during the solidification process of the continuous 15 casting operation. With this process, because of the maximum length allowed in the continuous casting machine for solidification and because the stral1d is essentially parallel, there is enough flexibility to slow down the machine to allow a shand stoppage. Typically such a conventional continuous casting machine would have sufficient flexibility to allow a strand stoppage of up to 20 three minutes which allows the tundish change to takes place.
GB 1145860 discloses an apparatus and method for the continuous casting of metal having tundishes which, as the time for changeover of the tundish approaches, pour metal continuously into the mould. This is achieved by the 25 use of refractory chutes which, in this simultaneous pouring stage, transfers the molten metal from the nozzle of the tundishes to the mould. Thus metal is continuously poured whilst the tundish is changed over. The problem with this method however is that the chutes get clogged up with molten metal l)ecause it is difficult to m:~int:~in a sufficiently high temperature in the chute. Also 30 oxidation of the metal occurs in the chute which results in diminished ~luality of the final product and loss of yield. The molten metal falls from the chute into the mould through the opening 90.
There are additional significant disadvantages with all the above conventional methods. It is not possible to increase the casting speed significantly without c~ . significant interruption problems. Additionally there are inlelluplion problems with lower strand thicknesses. Additionally, and more recently 5 casting machines have been developed which are tapered such that the cast section is gradually reduced after initial forming in the mould and before finalsolidification. These circumstances mean that it is not possible to slow down or stop the casting process for a sufficient length of time to allow the conventional flying tundish change method and therefore long runs are not 10 possible for these specific circumstances.
It is therefore an objective of the invention to provide a tundish change methodand an apparatus therefore and tundish shape which enables long casting runs for reduced strand thickness as well as for tapering of the castin~ machine. lt is 15 also an objective of the invention to provide a tundish change method and tundish therefore which allows long casting runs to be continuous and unilltellupted at increased speeds.
According to the invention there is provided a method of continuous casting of 20 metal, comprising pouring the molten metal from a tundish into a mould thlougll a tap hole in a base wall of the tundish, and wherein first and second tundishes each comprising a corresponding first and second tap hole and associated first and second nozzle means, are used to enable the flow of molten metal to be continuous or nearly continuous, such that when one of the first 25 tundish is required to be changed it is moved into a first tundish changeoverposition, and the second tundish is moved into a second tundish changeover position, and wherein in the changeover position both the first and second tundishes are in position over the mould so that metal may flow from both tundishes simultaneously into the mould, characterised in that in the 30 chall~eover position tlle first and second nozzle meatls of the first ~nd second tundishes are immersed in the molten metal in the mould.
ln the first stage of the preferred method of the invention a first tundish in the casting position is positioned over the mould so that molten metal can flow 35 tllrougll tlle lap llole inlo ~lle moul~l. Tllc rlrst lu~ isll is lyl)ieally loealc(l 400 mm above the mould and a pouring tube directs the flow of metal from the tundish into the mould. A second tundish is in a position alongside the first tundish in the plan view.
5 In the second stage of the method of the invention, which occurs when the level of the molten metal in the first tundish has reached a pre-determined low level,the second tundish is lowered to the level of the fill position, which is in a preferred embodiment approximately 400 mm above the mould. Then both the first and second tundishes are positioned so that the tap hole of the second 10 tundish is also located over the mould. Although the first tap hole has been moved sideways with the first tundish, it nevertheless is still in a position over the mould and molten metal is still flowing into the mould from the first tundish. The tap hole of the second tundish is then opened so that molten metal flows from the second tundish into the mould. Preferably the flow from the 15 first and second tundishes will be regularised so that is does not exceed a prescril~ed rate which is preferably the same rate as a single tap hole when fully open. The flow rate is preferably regulated by tap hole valves which may l~e controlled by suitable control systems. Preferably this stage is maintained until the first tundish is emptied at which point the flow from its tap hole is zero and 20 the flow from the second tundish tap hole is correspondingly regulated to the required full flow.
Preferably the tap holes of the fist and second tundishes are arranged symmetrically on either side of a centreline of the mould.
According to a subsequent third stage of the method of the invention, when the first tundish is empty its tap hole is closed and it is raised above the level of the fill position and moved to a park position. The second tundish is then able to be moved sideways to a position where the tap hole of the second tundish is 30 positioned centrally in the mould. This is the pl~;relled position when the whole of the flow is coming from a single tundish.
Accordillg to a fourth stage of the method of the invention, the first tundish is located in the side ways to a parking position above the fill level which permits a third tundish to be moved into position ready for the cycle to be repeated agam.
According to the invention there is also provided a continuous casting 5 apparatus for carrying out the method described above. The apparatus comprises the two tundishes which are so shaped as to each have top sides which when the tundishes are arranged so that the corresponding sides of each tundishes are abutting, the tap holes of the corresponding tundishes are close to each other. This enables pouring to occur simultaneously from both of the tap 10 holes into the mould for casting strands with a strand width which is at least as wide as the distance between the respective tap holes.
According to the invention there is also provided a tundisll which comprises sides two front sides, two long sides, two short sides and a rear side, a base 15 and an open or closed top. The tap hole is arranged at the top end of the tundish in the base so that molten metal flows out downwaldly, into the paper as shown, into the mould. The base comprises slightly angled surfaces, angled towards the tap hole, to enable the molten metal to flow towards the tap hole.
The tundish is so arranged so that the tap hole is a close as possible to the front 20 sides so that the distance between the tap holes of corresponding tundishes when in the position when both tundishes are pouring simultaneously, is minimised. The front sides could be arranged to be non-symmetrical and at any desired angle.
25 One side may be more acute angle to make that side closer to the tap hole.
Preferably the top sides are symmetrical and forming an apex of 90 degrees.
There now follows a more detailed description of a specific embodiment of the method and apparatus according to the invention with the help of the attached 30 drawings in which:
Fig. 1 is a plan view of a first stage the existing tundish change method, Fig. 2 is a plan view of a second stage of the existing tundish change 35 method, Fig. 3 is a plan view of a third stage of the existing tundish change method, 5 Fig. 4 is a plan view of the apparatus of the embodiment of the invention in a first stage of the method of the invention, Fig. 5 is a plan view of the apparatus of the embodiment of the invention in a second stage of the method of the invention, Fig. 6 is a plan view of the apparatus of the eml~odiment of the invention in a third stage of the method of the invention, Fig. 7 is a plan view of the ~pal~lus of the eml)odiment of the 15 invention in a fourth stage of the method of the invention, - Fig. 8 is an enlarged plan view of the apparatus of the embodiment of the invention, 20 Fig. 9 is an enlarged plan view of the tundish of the apparatus of the embodiment of the invention, and Fig. 10 is an elevation of the casting apparatus of the present invention.
Figures 1 to 3 showing a conventional method of tundish changeover as described above. When the first tundish 1 is expended the tap hole 3 is closed and the first tundish 1 is moved to the left to a parking position.
Simultaneously the second tundish 2 is moved into the moulding position and 30 its tap l~olc 4 is opcllcd ~l~d thc flow of moltell met~l into the mollld re-commences. It is clear to see that with this method the flow of molten metal into the mould is actually stopped for the period of time it takes to cany out these steps from the closing of the tap hole 3 to the opening of the tay hole 4.
Referring now to figures 4 to 7, the apparatus accordin~ to the embodiment of the invention is shown as well as four stages of lhe mefllod of tlle illventioIl. In figure 4 a first tundish 11 is shown in the casting position and is positioned over the mould 15 so that molten metal can flow through the tap hole 13 into 5 the mould 15. The first tundish 11 is typically located 400 mm above the mould and a pouring tube, or nozzle means, directs flow to the mould. In this casting position the first tundish is arranged so that the pouring tube is arranged centrally in the mould and is immersed in the molten metal. The tap hole 13 is fully open. A second tundish 12 is in a position alongside the first tundish 11 10 in the plan view. This position is called a pre-casting position.
Referring now to figure 5 a second stage in the method of the invention is shown which occurs when the level of the molten metal in the first tundish 11 has reached a pre-determined low level. The second tundish 12 is then 15 positioned at a mould filling pOSitiOll, which is approximately 400 mm al)ove the mould. Additionally both the first and second tundishes are moved sideways to corresponding changeover position, in which the tap hole 14 of the second tundish 12 is also positioned over the mould 15. Although the first tap hole 13 has been moved sideways with the first tundish 11, it nevertheless is 20 still also in a position over the mould 15 and molten metal is still flowing into the mould from the first tundish 11. The tap hole 14 of the second tundish 12 is then opened so that molten metal flows from the second tundish into the mould 15. At this point molten metal is flowing from both the first and second tundishes into the mould. The flow will be regularised so that is does not 25 exceed a prescribed rate which is preferably the same rate as a single tap hole when fully open. So the flow rate will be made up of a portion of the flow rate from tap hole 13 and a portion of the flow rate from tap hole 14. This could be for example half of the normal flow rate from each of the tap holes 13, 14. The flow rate is regulated by tap hole valves which are known in the alt and which 30 may be controlled by suitable control systems, which would also be apparent to the person skilled in the art, so that the desired flow from any one tap hole and hence the total flow can be controlled. This stage is m:lint:lined until the first tundish 11 is emptied at which point the flow from tap hole 13 is zero and the flow from tap hole 14 is correspondingly increased to full flow, i.e. it is opened 35 complelely. Tlle flow ol' llle mollell mclal illlo llle moul(l llas lllcrel'olc l)ccll maintained at a constant flow rate and there has been no interruption, or essentially no interruptioll, in the flow rate during the changeover of the tundishes.
5 Referring now to figure 6, the first tundishes 11 is moved upwardly above the fill level out of the paper in figure 6 to permit the second tundish 12 to move to a position where the tap hole 14 of the second tundish 12 is positioned centrally in the mould 15. This is the preferred position when the whole of the flow is coming from a single tundish.
Referring now to figure 7, the first tundish 11 is then moved side ways (to the left in figure 7) to a parking position so that a third tundish can be moved into position ready for the cycle to be repeated again.
15 Referring now to figure 8 an enlarged view of the continuous casting apparatus of the invention is shown in the changeover position when both tundishes are pouring molten metal, into tlle mould just before one of them is emptied and moved out of position. It can l~e seen from the figure that the apparatus comprises the two tundishes 11, 12 which are so shaped as to each have top 20 sides 16, 17 which when the tundishes are arranged so that the corresponding sides of each tundishes are abutting, the tap holes 13, 14 of the corresl)ondingtundishes are close to each other. It will be appreciated that when the tundishes are compared to the tundishes of the prior art it can l)e seen that the distancebetween the corresponding tap holes of the prior art tundishes is much greater.
25 This enables pouring to occur simultaneously from both of the tap holes into the mould 15 for casting strands with a strand width which is at least as wide as the distance between the respective tap holes 13, 14.
Referring to figure 9 an enlarged view of a single tundish of the invention is 30 shown which comprises sides two front sides 16, 17, two long sides 18, 19 twoshort sides 21, 22 and a rear side 23. The tap hole is arranged at the top end of the tundish 11 in the base so that molten metal flows out downwardly, into the paper as shown, into the mould. The l~ase 24 comprises surfaces which are angled towards the tap hole. The tundish is so arranged so that the tap hole 13 35 is a close as possil)le lo lhe liont sides 16, 17 so lhal lile (lislallcc ~elweell llle tap holes 13, 14 of corresponding tundishes when in the position in figure 8, isminimi.~ed. lt will be appreciated that within the scope of the invention the top sides could l)e arranged to be non-symmettical and at any desired aulgle. One side could for instance be made at and significantly more acute angle to make S that side closer to the tap hole 13 so that when it is abutted against a corresponding side of a second tundish the distance between the conesponding tap holes is reduced. The embodiment shown however, with the top sides symmetrical and forming an apex of 90 degrees, has the advantage that the tundishes can be used from either side which simplifies the changeover 10 operation and reduces the required inventory of spare tundishes. lt will be appreciated that the apex could be at an alternative desired angle.
In order that even narrower strands of mould can be accommodated using thc present invention to avoid any interruptions to the flow, it is possible to provide 15 an angled pouring tube which directs the flow of molten metal from the tap hole inwardly into the narrow mould. Thus moulds for strands which are narrower than the distance between the tap holes of corresponding tundishes can be used.
20 Referring now to fig. 10 a side elevation of the apparatus, is shown to show the complete operation of the casting appatatus and method of the invention. The tundishes 11, 12 are charged from a ladle 8 as shown schematically in fig. 10.
In the 11, 12 have corresponding pouring tul)es 9, 10 which are immersed in the molten metal in the mould 15. The tundishes are shown in fig. 10 in their 25 corresponding changeover positions with both tundishes 11, 12 discharging metal and both pouring tubes 9, 10 immersed in the molten metal in the mould 15. When the first tundish 11 is empty it is closed and moved upwards in figure 10 and then sideways out of the page in fig. 10 to a parking position allowing the second tundish to adopt a central poring pOSitiOII over the mould 30 and a new tundish to ready to be moved into the moulding positions when the second tundish is nearly empty. So in the same way as with the second tundish the new tundish adopts a changeover position when the second tundish is nearly empty with both tundishes pouring, followed by a central pouring position when the second tundish has moved off to its parking position.
After exiting the mould 15 the molten metal enters a series of casting rolls forming a strand support 32 during which the metal solidifies completely and then enters the subsequent operational steps 33 as a fully cast strand or slab.
5 The present invention relates to a continuous casting method and apparatus therefore including a new tundish design for ensuring the continuous casting method may be continued for long casting runs with minimised interruption.
ln td1e continuous casting of metals and in particular steel it is advantageous to 10 extend the length of the cast. This provides two main advantages. Firstly, itm~ximi~es the duration of the steady state conditions when the best product quality is achieved and this in turn reduces the amount of scrap steel produced typically from the begim1ing and end portions of a casting run which are not of sufficiently quality and it also improves the overall quality of the finished 15 product. Secondly production levels are m~ximised and the existing plant and equipment is able to be utilised to a greater extent which improves the return on investment.
There is an additional advalltage in that the length of the cast can be optimised 20 with the duration of the available life from the wear components in the casting process which can be changed at the end of each cast. Thus if the cast is long enough the full life of the main wear components can be used which reduces downtime and the cost of replacement of the wear parts.
25 Duril1g the casting process metal is poured thlough a tap hole in a vessel and this vessel is typically in the form of a tundish. ln order to extend the desired casting time it is necessary to replace the tundish a nurmber of times after each time its life is expended. In particular for the casting of fenous metals such as steel, the high temperature chemical aggression and physical erosion of the 30 refractory material of the tundish permits the tundish to run continuously for only short periods before they have to be exchanged cleaned of slag and relined. Thus it is necessary to changeover the tundish a number of times in order to continuously cast the steel over a long period. Such tundish changes are sometimes known as flying tundish changes.
A known method of ch~n,Qing over tundishes and a tundish used is shown in figures 1 to 3. ln figure 1 the first tundish is in the casting position over the mould and the second tundish 2 is in a "waiting to cast" position to one side.
When it is time to change the first tundish 1, the first tundish 1 remains in the 5 casting position until all the metal in the first tundish 1 is poured into the mould 5. The tap hole is then closed and the first tundish 1 is moved sideways to a parking position as shown in figure 2. Simultaneously the second tundish is moved sideways from a pre-fill position into the casting position over the mould 5. When it is in the desired casting position, as shown in figure 3, it is10 filled with metal and its tap hole is opened and casting can recommence.
This conventional tundisll changeover method is acceptable for standard conventional continuous casting runs. In such runs a strand which is essentially parallel is formed during the solidification process of the continuous 15 casting operation. With this process, because of the maximum length allowed in the continuous casting machine for solidification and because the stral1d is essentially parallel, there is enough flexibility to slow down the machine to allow a shand stoppage. Typically such a conventional continuous casting machine would have sufficient flexibility to allow a strand stoppage of up to 20 three minutes which allows the tundish change to takes place.
GB 1145860 discloses an apparatus and method for the continuous casting of metal having tundishes which, as the time for changeover of the tundish approaches, pour metal continuously into the mould. This is achieved by the 25 use of refractory chutes which, in this simultaneous pouring stage, transfers the molten metal from the nozzle of the tundishes to the mould. Thus metal is continuously poured whilst the tundish is changed over. The problem with this method however is that the chutes get clogged up with molten metal l)ecause it is difficult to m:~int:~in a sufficiently high temperature in the chute. Also 30 oxidation of the metal occurs in the chute which results in diminished ~luality of the final product and loss of yield. The molten metal falls from the chute into the mould through the opening 90.
There are additional significant disadvantages with all the above conventional methods. It is not possible to increase the casting speed significantly without c~ . significant interruption problems. Additionally there are inlelluplion problems with lower strand thicknesses. Additionally, and more recently 5 casting machines have been developed which are tapered such that the cast section is gradually reduced after initial forming in the mould and before finalsolidification. These circumstances mean that it is not possible to slow down or stop the casting process for a sufficient length of time to allow the conventional flying tundish change method and therefore long runs are not 10 possible for these specific circumstances.
It is therefore an objective of the invention to provide a tundish change methodand an apparatus therefore and tundish shape which enables long casting runs for reduced strand thickness as well as for tapering of the castin~ machine. lt is 15 also an objective of the invention to provide a tundish change method and tundish therefore which allows long casting runs to be continuous and unilltellupted at increased speeds.
According to the invention there is provided a method of continuous casting of 20 metal, comprising pouring the molten metal from a tundish into a mould thlougll a tap hole in a base wall of the tundish, and wherein first and second tundishes each comprising a corresponding first and second tap hole and associated first and second nozzle means, are used to enable the flow of molten metal to be continuous or nearly continuous, such that when one of the first 25 tundish is required to be changed it is moved into a first tundish changeoverposition, and the second tundish is moved into a second tundish changeover position, and wherein in the changeover position both the first and second tundishes are in position over the mould so that metal may flow from both tundishes simultaneously into the mould, characterised in that in the 30 chall~eover position tlle first and second nozzle meatls of the first ~nd second tundishes are immersed in the molten metal in the mould.
ln the first stage of the preferred method of the invention a first tundish in the casting position is positioned over the mould so that molten metal can flow 35 tllrougll tlle lap llole inlo ~lle moul~l. Tllc rlrst lu~ isll is lyl)ieally loealc(l 400 mm above the mould and a pouring tube directs the flow of metal from the tundish into the mould. A second tundish is in a position alongside the first tundish in the plan view.
5 In the second stage of the method of the invention, which occurs when the level of the molten metal in the first tundish has reached a pre-determined low level,the second tundish is lowered to the level of the fill position, which is in a preferred embodiment approximately 400 mm above the mould. Then both the first and second tundishes are positioned so that the tap hole of the second 10 tundish is also located over the mould. Although the first tap hole has been moved sideways with the first tundish, it nevertheless is still in a position over the mould and molten metal is still flowing into the mould from the first tundish. The tap hole of the second tundish is then opened so that molten metal flows from the second tundish into the mould. Preferably the flow from the 15 first and second tundishes will be regularised so that is does not exceed a prescril~ed rate which is preferably the same rate as a single tap hole when fully open. The flow rate is preferably regulated by tap hole valves which may l~e controlled by suitable control systems. Preferably this stage is maintained until the first tundish is emptied at which point the flow from its tap hole is zero and 20 the flow from the second tundish tap hole is correspondingly regulated to the required full flow.
Preferably the tap holes of the fist and second tundishes are arranged symmetrically on either side of a centreline of the mould.
According to a subsequent third stage of the method of the invention, when the first tundish is empty its tap hole is closed and it is raised above the level of the fill position and moved to a park position. The second tundish is then able to be moved sideways to a position where the tap hole of the second tundish is 30 positioned centrally in the mould. This is the pl~;relled position when the whole of the flow is coming from a single tundish.
Accordillg to a fourth stage of the method of the invention, the first tundish is located in the side ways to a parking position above the fill level which permits a third tundish to be moved into position ready for the cycle to be repeated agam.
According to the invention there is also provided a continuous casting 5 apparatus for carrying out the method described above. The apparatus comprises the two tundishes which are so shaped as to each have top sides which when the tundishes are arranged so that the corresponding sides of each tundishes are abutting, the tap holes of the corresponding tundishes are close to each other. This enables pouring to occur simultaneously from both of the tap 10 holes into the mould for casting strands with a strand width which is at least as wide as the distance between the respective tap holes.
According to the invention there is also provided a tundisll which comprises sides two front sides, two long sides, two short sides and a rear side, a base 15 and an open or closed top. The tap hole is arranged at the top end of the tundish in the base so that molten metal flows out downwaldly, into the paper as shown, into the mould. The base comprises slightly angled surfaces, angled towards the tap hole, to enable the molten metal to flow towards the tap hole.
The tundish is so arranged so that the tap hole is a close as possible to the front 20 sides so that the distance between the tap holes of corresponding tundishes when in the position when both tundishes are pouring simultaneously, is minimised. The front sides could be arranged to be non-symmetrical and at any desired angle.
25 One side may be more acute angle to make that side closer to the tap hole.
Preferably the top sides are symmetrical and forming an apex of 90 degrees.
There now follows a more detailed description of a specific embodiment of the method and apparatus according to the invention with the help of the attached 30 drawings in which:
Fig. 1 is a plan view of a first stage the existing tundish change method, Fig. 2 is a plan view of a second stage of the existing tundish change 35 method, Fig. 3 is a plan view of a third stage of the existing tundish change method, 5 Fig. 4 is a plan view of the apparatus of the embodiment of the invention in a first stage of the method of the invention, Fig. 5 is a plan view of the apparatus of the embodiment of the invention in a second stage of the method of the invention, Fig. 6 is a plan view of the apparatus of the eml~odiment of the invention in a third stage of the method of the invention, Fig. 7 is a plan view of the ~pal~lus of the eml)odiment of the 15 invention in a fourth stage of the method of the invention, - Fig. 8 is an enlarged plan view of the apparatus of the embodiment of the invention, 20 Fig. 9 is an enlarged plan view of the tundish of the apparatus of the embodiment of the invention, and Fig. 10 is an elevation of the casting apparatus of the present invention.
Figures 1 to 3 showing a conventional method of tundish changeover as described above. When the first tundish 1 is expended the tap hole 3 is closed and the first tundish 1 is moved to the left to a parking position.
Simultaneously the second tundish 2 is moved into the moulding position and 30 its tap l~olc 4 is opcllcd ~l~d thc flow of moltell met~l into the mollld re-commences. It is clear to see that with this method the flow of molten metal into the mould is actually stopped for the period of time it takes to cany out these steps from the closing of the tap hole 3 to the opening of the tay hole 4.
Referring now to figures 4 to 7, the apparatus accordin~ to the embodiment of the invention is shown as well as four stages of lhe mefllod of tlle illventioIl. In figure 4 a first tundish 11 is shown in the casting position and is positioned over the mould 15 so that molten metal can flow through the tap hole 13 into 5 the mould 15. The first tundish 11 is typically located 400 mm above the mould and a pouring tube, or nozzle means, directs flow to the mould. In this casting position the first tundish is arranged so that the pouring tube is arranged centrally in the mould and is immersed in the molten metal. The tap hole 13 is fully open. A second tundish 12 is in a position alongside the first tundish 11 10 in the plan view. This position is called a pre-casting position.
Referring now to figure 5 a second stage in the method of the invention is shown which occurs when the level of the molten metal in the first tundish 11 has reached a pre-determined low level. The second tundish 12 is then 15 positioned at a mould filling pOSitiOll, which is approximately 400 mm al)ove the mould. Additionally both the first and second tundishes are moved sideways to corresponding changeover position, in which the tap hole 14 of the second tundish 12 is also positioned over the mould 15. Although the first tap hole 13 has been moved sideways with the first tundish 11, it nevertheless is 20 still also in a position over the mould 15 and molten metal is still flowing into the mould from the first tundish 11. The tap hole 14 of the second tundish 12 is then opened so that molten metal flows from the second tundish into the mould 15. At this point molten metal is flowing from both the first and second tundishes into the mould. The flow will be regularised so that is does not 25 exceed a prescribed rate which is preferably the same rate as a single tap hole when fully open. So the flow rate will be made up of a portion of the flow rate from tap hole 13 and a portion of the flow rate from tap hole 14. This could be for example half of the normal flow rate from each of the tap holes 13, 14. The flow rate is regulated by tap hole valves which are known in the alt and which 30 may be controlled by suitable control systems, which would also be apparent to the person skilled in the art, so that the desired flow from any one tap hole and hence the total flow can be controlled. This stage is m:lint:lined until the first tundish 11 is emptied at which point the flow from tap hole 13 is zero and the flow from tap hole 14 is correspondingly increased to full flow, i.e. it is opened 35 complelely. Tlle flow ol' llle mollell mclal illlo llle moul(l llas lllcrel'olc l)ccll maintained at a constant flow rate and there has been no interruption, or essentially no interruptioll, in the flow rate during the changeover of the tundishes.
5 Referring now to figure 6, the first tundishes 11 is moved upwardly above the fill level out of the paper in figure 6 to permit the second tundish 12 to move to a position where the tap hole 14 of the second tundish 12 is positioned centrally in the mould 15. This is the preferred position when the whole of the flow is coming from a single tundish.
Referring now to figure 7, the first tundish 11 is then moved side ways (to the left in figure 7) to a parking position so that a third tundish can be moved into position ready for the cycle to be repeated again.
15 Referring now to figure 8 an enlarged view of the continuous casting apparatus of the invention is shown in the changeover position when both tundishes are pouring molten metal, into tlle mould just before one of them is emptied and moved out of position. It can l~e seen from the figure that the apparatus comprises the two tundishes 11, 12 which are so shaped as to each have top 20 sides 16, 17 which when the tundishes are arranged so that the corresponding sides of each tundishes are abutting, the tap holes 13, 14 of the corresl)ondingtundishes are close to each other. It will be appreciated that when the tundishes are compared to the tundishes of the prior art it can l)e seen that the distancebetween the corresponding tap holes of the prior art tundishes is much greater.
25 This enables pouring to occur simultaneously from both of the tap holes into the mould 15 for casting strands with a strand width which is at least as wide as the distance between the respective tap holes 13, 14.
Referring to figure 9 an enlarged view of a single tundish of the invention is 30 shown which comprises sides two front sides 16, 17, two long sides 18, 19 twoshort sides 21, 22 and a rear side 23. The tap hole is arranged at the top end of the tundish 11 in the base so that molten metal flows out downwardly, into the paper as shown, into the mould. The l~ase 24 comprises surfaces which are angled towards the tap hole. The tundish is so arranged so that the tap hole 13 35 is a close as possil)le lo lhe liont sides 16, 17 so lhal lile (lislallcc ~elweell llle tap holes 13, 14 of corresponding tundishes when in the position in figure 8, isminimi.~ed. lt will be appreciated that within the scope of the invention the top sides could l)e arranged to be non-symmettical and at any desired aulgle. One side could for instance be made at and significantly more acute angle to make S that side closer to the tap hole 13 so that when it is abutted against a corresponding side of a second tundish the distance between the conesponding tap holes is reduced. The embodiment shown however, with the top sides symmetrical and forming an apex of 90 degrees, has the advantage that the tundishes can be used from either side which simplifies the changeover 10 operation and reduces the required inventory of spare tundishes. lt will be appreciated that the apex could be at an alternative desired angle.
In order that even narrower strands of mould can be accommodated using thc present invention to avoid any interruptions to the flow, it is possible to provide 15 an angled pouring tube which directs the flow of molten metal from the tap hole inwardly into the narrow mould. Thus moulds for strands which are narrower than the distance between the tap holes of corresponding tundishes can be used.
20 Referring now to fig. 10 a side elevation of the apparatus, is shown to show the complete operation of the casting appatatus and method of the invention. The tundishes 11, 12 are charged from a ladle 8 as shown schematically in fig. 10.
In the 11, 12 have corresponding pouring tul)es 9, 10 which are immersed in the molten metal in the mould 15. The tundishes are shown in fig. 10 in their 25 corresponding changeover positions with both tundishes 11, 12 discharging metal and both pouring tubes 9, 10 immersed in the molten metal in the mould 15. When the first tundish 11 is empty it is closed and moved upwards in figure 10 and then sideways out of the page in fig. 10 to a parking position allowing the second tundish to adopt a central poring pOSitiOII over the mould 30 and a new tundish to ready to be moved into the moulding positions when the second tundish is nearly empty. So in the same way as with the second tundish the new tundish adopts a changeover position when the second tundish is nearly empty with both tundishes pouring, followed by a central pouring position when the second tundish has moved off to its parking position.
After exiting the mould 15 the molten metal enters a series of casting rolls forming a strand support 32 during which the metal solidifies completely and then enters the subsequent operational steps 33 as a fully cast strand or slab.
Claims (15)
1. A method of continuous casting of metal, comprising pouring the molten metal from a tundish into a mould through a tap hole in a base wall of the tundish, and wherein first and second tundishes, each comprising a corresponding first and second tap hole and associated corresponding first and second pouring nozzle means, are used to enable the flow of molten metal to be continuous or nearly continuous, such that when the first tundish nears the timewhen it is required to be changed, it is moved into a first tundish changeover position, and the second tundish is moved into a second tundish changeover position, and wherein in the corresponding changeover positions both the first and second tundishes are in position over the mould so that metal may flow from both tundishes simultaneously into the mould, characterised in that during pouring in the corresponding changeover positions the first and second nozzle means of the first and second tundishes remain immersed in the molten metal in the mould.
2. A method of continuous casting of metal, comprising pouring the molten metal from a tundish into a mould through a tap hole in a base wall of the tundish, and wherein first and second tundishes each comprising a corresponding first and second tap hole and associated corresponding first and second pouring nozzle means, are used to enable the flow of molten metal to be continuous or nearly continuous, such that in a first stage, the first tundish is arranged in a casting position with its pouring nozzle arranged centrally over the mould and metal is cast from the first tundish into the mould, and in a second stage, when the first tundish nears the time when it is required to be changed it is moved into a first tundish changeover position, and the second tundish is moved into a second tundish changeover position, and wherein in the corresponding changeover positions both the first and second tundishes are in position over the mould so that metal may flow from both tundishes simultaneously into the mould until, in a third stage, when the first tundish isemptied, it is moved from its changeover position and the second tundish is moved to the casting position with its pouring tube arranged centrally in the mould.
3. A method according to claim 1 or 2 characterised in that the combined flow from the first and second tundishes is approximately equal to the required full flow from one tundish.
4. A method according to claim 2, characterised in that the pouring nozzle means are submerged in the molten metal and direct the flow of metal from the tundish into the mould.
5. A method according to claim 1, characterised in that when the level of the molten metal in the first tundish has reached a pre-determined low level, the second tundish is moved towards the changeover position and is located adjacent to the first tundish.
6. A method according to claim 5, characterised in that the first tundish and a first tap hole associated therewith is moved sideways from the casting position to the changeover position but is still in a position over the mould and molten metal is still flowing into the mould from the first tundish.
7. A method according to claim 6, characterised in that the second tundish is moved with the first tundish, in the same direction such that a second tap hole associated with the second tundish is over the mould and the second tundish is lowered until its pouring nozzle means is submerged in the molten metal and the second tap hole is then opened so that molten metal flows from the second tundish into the mould.
8. A method according to claim 7, characterised in that the flow from the first and second tundishes is regulated so that the combined flow rate does not exceed a prescribed rate.
9. A method according to claim 7, characterised in that the flow from the first and second tundishes is maintained until the first tundish is emptied at which point the flow from its tap hole is zero and the flow from the second tundish tap hole is correspondingly regulated to the required full flow.
10. A method according to claim 9, characterised in that the first tundish is then closed and raised and moved away to a parking position, in which position a further third tundish can be moved into position over the mould ready for the cycle to be repeated again.
11. A continuous casting apparatus for carrying out the method described in claim 1, the apparatus comprising at least two tundishes which are so shaped as to each have front sides which, when the tundishes are arranged so that the corresponding front sides of each tundishes are abutting, the tap holes of the corresponding tundishes are close enough to each other to enable pouring to occur simultaneously from both of the tap holes into the mould for casting strands with a strand width which is at least as wide as the distance between the respective tap holes.
12. An apparatus according to claim 11, characterised in that a tap hole valve is arranged to correspond with the tap holes of each tundish to control the flow rate.
13. An apparatus according to claim 11, characterised in that at least one of the tundishes comprises two front sides, two long sides and a rear side, a base and an open or closed top and a tap hole arranged at the top end of the tundish in the base so that molten metal flows out downwardly, into the mould, the base comprising at least one angled surface, angled towards the tap hole, to enable the molten metal to flow towards the tap hole, the tundish is so arrangedso that the tap hole is as close as possible to the top sides so that the distance between the tap holes of corresponding tundishes when in the position when both tundishes are pouring simultaneously, is minimised.
14. A tundish according to claim 13, characterised in that the front sides are symmetlical.
15. A tundish according to claim 13, characterised in that the front sides form an apex of 90 degrees.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GBGB9703510.9A GB9703510D0 (en) | 1997-02-20 | 1997-02-20 | Continuous casting method and apparatus therefore |
| GB9703510.9 | 1997-02-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2230044A1 true CA2230044A1 (en) | 1998-08-20 |
Family
ID=10807995
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2230044 Abandoned CA2230044A1 (en) | 1997-02-20 | 1998-02-19 | Continuous casting method and apparatus therefor |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0861697A1 (en) |
| JP (1) | JPH10314900A (en) |
| AU (1) | AU5539398A (en) |
| CA (1) | CA2230044A1 (en) |
| GB (2) | GB9703510D0 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10012961A1 (en) | 2000-03-16 | 2001-09-20 | Bosch Gmbh Robert | High pressure part for fuel injection system; has intersecting bores, where at least one bore has flat part and part has internal pressure stresses in area of flat part |
| CN108356254A (en) * | 2018-02-13 | 2018-08-03 | 东北大学 | A kind of abnormity Multi-strand Continuous Casting sensing heating tundish device |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE903024C (en) * | 1948-11-23 | 1954-02-01 | E H Siegfried Junghans Dr Ing | Process and system for the continuous casting of high-melting materials such as steel |
| US3382913A (en) * | 1965-08-25 | 1968-05-14 | Bliss E W Co | Apparatus for uninterrupted continuous casting |
| US3333746A (en) * | 1966-05-19 | 1967-08-01 | Harbison Walker Refractories | Tundish ladles |
| AT280508B (en) * | 1968-08-23 | 1970-04-10 | Voest Ag | Process for the production of strands in the continuous casting process and device for carrying out the process |
| GB1274084A (en) * | 1969-12-05 | 1972-05-10 | Anatoly Mikhailovitch Gora | Pouring metal into a mould |
| US3707183A (en) * | 1970-09-23 | 1972-12-26 | Luigi Danieli | Continuous offset line casting arrangement |
| AT314120B (en) * | 1970-12-14 | 1974-03-25 | Voest Ag | Process for the fully continuous casting of molten metals, especially steel |
| IT1180436B (en) * | 1984-02-24 | 1987-09-23 | Continua Int | METHOD AND DEVICE FOR THE SUPPLY OF CONTINUOUS CASTING PLANTS |
| US4903752A (en) * | 1988-08-10 | 1990-02-27 | Rokop Corporation | Hot metal supply for continuous casing and the like |
-
1997
- 1997-02-20 GB GBGB9703510.9A patent/GB9703510D0/en active Pending
-
1998
- 1998-02-10 GB GB9802706A patent/GB2322321B/en not_active Expired - Fee Related
- 1998-02-19 EP EP98301250A patent/EP0861697A1/en not_active Withdrawn
- 1998-02-19 CA CA 2230044 patent/CA2230044A1/en not_active Abandoned
- 1998-02-19 AU AU55393/98A patent/AU5539398A/en not_active Abandoned
- 1998-02-20 JP JP3932998A patent/JPH10314900A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| AU5539398A (en) | 1998-08-27 |
| EP0861697A1 (en) | 1998-09-02 |
| JPH10314900A (en) | 1998-12-02 |
| GB9703510D0 (en) | 1997-04-09 |
| GB2322321A (en) | 1998-08-26 |
| GB2322321B (en) | 1999-06-09 |
| GB9802706D0 (en) | 1998-04-08 |
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