EP0186852B2 - Tundish for continuous casting of free cutting steel - Google Patents
Tundish for continuous casting of free cutting steel Download PDFInfo
- Publication number
- EP0186852B2 EP0186852B2 EP85116118A EP85116118A EP0186852B2 EP 0186852 B2 EP0186852 B2 EP 0186852B2 EP 85116118 A EP85116118 A EP 85116118A EP 85116118 A EP85116118 A EP 85116118A EP 0186852 B2 EP0186852 B2 EP 0186852B2
- Authority
- EP
- European Patent Office
- Prior art keywords
- tundish
- molten steel
- dam
- steel
- zone
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000009749 continuous casting Methods 0.000 title claims description 7
- 229910000915 Free machining steel Inorganic materials 0.000 title claims description 3
- 229910000831 Steel Inorganic materials 0.000 claims description 88
- 239000010959 steel Substances 0.000 claims description 88
- 239000011449 brick Substances 0.000 claims description 30
- 238000002844 melting Methods 0.000 claims description 18
- 229910052751 metal Inorganic materials 0.000 claims description 17
- 239000002184 metal Substances 0.000 claims description 17
- 230000008018 melting Effects 0.000 claims description 15
- 239000006185 dispersion Substances 0.000 claims description 9
- 238000011144 upstream manufacturing Methods 0.000 claims 5
- 238000010276 construction Methods 0.000 claims 1
- 230000009977 dual effect Effects 0.000 claims 1
- 239000000843 powder Substances 0.000 description 35
- 239000007789 gas Substances 0.000 description 15
- 229910052797 bismuth Inorganic materials 0.000 description 13
- 229910052745 lead Inorganic materials 0.000 description 13
- 238000003756 stirring Methods 0.000 description 5
- 230000005587 bubbling Effects 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 230000005484 gravity Effects 0.000 description 3
- 238000007654 immersion Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- XNMARPWJSQWVGC-UHFFFAOYSA-N 2-[3-[11-[[5-(dimethylamino)naphthalen-1-yl]sulfonylamino]undecanoylamino]propoxy]-4-[(5,5,8,8-tetramethyl-6,7-dihydronaphthalene-2-carbonyl)amino]benzoic acid Chemical compound CC1(C)CCC(C)(C)C=2C1=CC(C(=O)NC=1C=C(C(=CC=1)C(O)=O)OCCCNC(=O)CCCCCCCCCCNS(=O)(=O)C1=C3C=CC=C(C3=CC=C1)N(C)C)=CC=2 XNMARPWJSQWVGC-UHFFFAOYSA-N 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 239000000161 steel melt Substances 0.000 description 2
- 229910001208 Crucible steel Inorganic materials 0.000 description 1
- 229910001021 Ferroalloy Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 230000000593 degrading effect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 229910000743 fusible alloy Inorganic materials 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 239000012629 purifying agent Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 210000003625 skull Anatomy 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
Images
Classifications
-
- 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
- B22D41/003—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like with impact pads
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D1/00—Treatment of fused masses in the ladle or the supply runners before casting
- B22D1/002—Treatment with gases
- B22D1/005—Injection assemblies therefor
-
- 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
- B22D11/11—Treating the molten metal
- B22D11/116—Refining the metal
- B22D11/117—Refining the metal by treating with gases
-
- 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
- B22D11/11—Treating the molten metal
- B22D11/116—Refining the metal
- B22D11/118—Refining the metal by circulating the metal under, over or around weirs
Definitions
- the present invention relates to a tundish for continuous casting of a free cutting molten steel added with Pb or Bi in order to promote the melting and dispersion thereof according to the preamble of claim 1.
- a free-cutting steel is produced by adding a machinability element to the molten steel, Pb, Bi, etc. are known as machinability elements.
- Japan examined patent application (referred to as Kokoku) No. 48(1973)-14524 proposes surrounding the ladle outlet with a dam to prevent the flow of Pb or Bi.
- Another Japan unexamined utility model application (referred to as Utility Model Kokai) No. 54(1979)-35715 proposes providing the bottom of the tundish with a dam to prevent undissolved alloy and nonmetallic inclusions from flowing into the mold.
- the methods generally used for adding a low melting alloy, a ferro-alloy or the like into the steel melt are that of adding the alloy to the steel melt being discharged from the steel converter and that of adding it directly into the ladle.
- a shroud is provided over the whole length of the molten steel flow downwardly from the ladle to the tundish and an inflow-pipe is installed at its forward end for introduction of PB onto the molten steel level in the tundish at an intermediate point of the vertical length of the shroud.
- a shroud is provided to surround the lower part of the molten steel flowing down from the ladle, and a dam is provided at the lower part thereof as immersed into the molten steel with the tundish.
- a steel purifying agent is droppingly added within the immersed dam.
- a prime object of the present invention is to provide a tundish for use in continuous casting in which undissolved Pb and Bi in the molten steel are prevented from flowing into the mold.
- Another object of the invention is to provide a tundish in which the Pb and Bi dissolution yield is greatly improved by forming a large circulation current of the molten steel so as to control the behaviour of the Pb and Bi.
- a tundish is provided with a molten steel teeming zone (referred to as teeming zone hereinafter) into which Pb or Bi (referred to as a low melting metal hereinafter) is added.
- the teeming zone is formed in the middle region of the tundish.
- a dispersing means which stirs the molten steel so as to promote uniform dispersion of the low melting metal is provided along a runner through which the molten steel runs from the teeming zone to a discharge outlet.
- an ejector having dispersing capabilities may be provided at the bottom of the tundish from which an inert gas such as Ar, N 2 etc, is ejected to stir the molten steel by gas bubbling action.
- At least one dam is provided downstream of the dispersing means in order to prevent the low melting metal from flowing into the discharge outlet for the molten steel.
- a ladle 1 a ladle nozzle 5 and a feed pipe 9 for the low melting metal.
- the main body 3 of a tundish 2 is provided with a cover 6, and dams 8, 8 are installed downstream in the direction of molten steel flow from gas ejectors 7, 7.
- the main body 3 is further provided with discharge outlets 10.
- a teeming zone is formed immediately below the nozzle 5, and a dispersing zone is formed between the gas ejectors 7, 7 and the dams 8, 8.
- Fig. 3 shows another embodiment of the invention, wherein the main body 3 of the tundish is formed with a projecting part4 (referred to as a T-type tundish hereinafter), and the ladle nozzle 5 is positioned nearly at the centre a of the projecting part 4.
- the teeming zone is defined by the position a of the ladle nozzle 5 and the projecting part 4, and the dispersion zone is formed between the dams 8, 8 and a single gas ejector 7.
- Fig. 5 shows another embodiment of the invention, wherein the teeming zone is defined by two inner weirs 12, 12 fixed to the cover 6 so as to enclose the center area of the tundish 2.
- the molten steel is teemed in the center portion.
- the reach inner weirs should be long enough to pass into the molten steel but not so long as to reach the base of the tundish.
- a convex portion 11, high in the middle and tapering off on both sides, is provided within the teeming zone surrounded by the inner weirs.
- Two outer weirs 13, 13 are suspended from the cover 6 of the tundish outside the teeming zone, and the gas ejectors 7, 7 are positioned in the bottom of the tundish between the inner weirs 12 and the outer weirs 13.
- the gas used is Ar or N 2 , and the gas ejector is preferably a porous plug.
- the outer weirs 13 should preferably be about the same length as the inner ones but are still effective even if longer or shorter.
- dams 8, 8 are provided on the bottom of the tundish outside the outer weirs 13, 13.
- the height of the dams 8, 8 should be less than the depth of the molten steel.
- the dispersion means is formed by providing the gas ejectors 7, 7 in the regions defined between the inner weirs 12, 12 and the dams 8, 8.
- a molten steel discharge outlets 10, 10 are positioned outside the dams 8, 8.
- the forward tip of the feed pipe 9 is directed to the stream of molten steel passing from the ladle 1 to the tundish 2 and so used to add a low melting metal to the molten steel in the form of a powder.
- the powder supplied by the feed pipe 9 is entrained by the descending steel stream due to its falling energy.
- the entrained powder is surrounded by the weirs 12, 12, almost none of it floats upward. It is thus transported by the descending stream of molten steel. While being so transported, the powder becomes well dispersed and dissolved.
- the action of the convex wall 11 at the bottom of the tundish causes the powder, particularly large undissolved particle thereof to move quickly to the dispersion zone.
- the molten steel is vigorously stirred by the bubbling action of the gas from the gas ejectors. By such stirring, the powder is dissolved and dispersed in the molten steel.
- Fig. 7 Another embodiment of the invention is shown in Fig. 7.
- the nozzle 5 is provided under the ladle 1, and a shroud 14 is provided to extend downward from the cover 6 of the tundish 2 so as to surround the lower part of the nozzle 5.
- the upper end of the shroud 14 is flush with the cover 6.
- the feed pipe 9 is provided to open into the space between the ladle nozzle 5 and the shroud 14.
- the lower end of the shroud 14 is immersed into the molten steel in the tundish.
- the shroud 14 is of oblong shape in horizontal section and surrounds the ladle nozzle 5. This embodiment has a single gas ejector 7.
- the optimum dimensions of the shroud fall within the following ranqe.
- the width A of the shroud should be less than three times the diameter d of the nozzle, the molten steel from the nozzle will splatter on the inside wall of the shroud, increasing the amount of skull adhering thereto and consequently making it impossible to add the powder to the molten steel.
- the stirring action of the molten steel in the shroud is so reduced that almost no stirring-in of the powder is attained.
- the depth of immersion C is less than 0.5 times the depth of the molten steel h
- the molten steel is dispersed out of the shroud in a short time and, and as a result, mixing of the powder into the molten steel is insufficient.
- the depth of immersion C exceeds 0.8 times the depth of the molten steel h, the solid powder which has been added, stirred and mixed remains in the shroud for a long time, preventing sufficient diffusion of the powder into the tundish.
- the molten steel stream from the nozzle is vigorously stirred within the shroud 14. Therefore, when the powder is added thereto, it is mixed and dispersed in the stirred stream of molten steel, and thereafter the molten steel is dispersed from the bottom of the shroud to the left and right regions of the tundish 2.
- Fig. 10, 11 depict a tundish of the type shown in Fig. 7 for use with one strand.
- Numerals 7-1, 7-2 and 7-3 designate gas ejectors.
- FIG. 12-15 illustrate further embodiments of this invention.
- a pair of inner dams 15, 15 and a pair of outer dams 8, 8 are provided on the bottom of the tundish 2.
- the ladle nozzle 5 is positioned between the inner dams 15, 15, while each outer dam 8 is positioned between one of the inner dams and one of a pair of discharge outlets 10.
- the inner dams 15, 15 and the outer dams 8, 8 have a length equal to the width of the tundish and are all of approximately the same height. Further, as illustrated in Fig. 12, the height of the dams is less than the depth of the molten steel.
- Figs 14 to 15 show a T-type tundish to which the principle of the invention is applied.
- a third inner dam 15 is provided so as to partition off the projecting part 4 of the tundish.
- A is the height of the inner dams 15, 15 and outer dams 8, 8; B is the distance between each inner dam 15 and the center of the ladle nozzle 5; C is the distance between each outer dam 8 and the center of the ladle nozzle 5; E is the depth of the molten steel; and F is the distance between the center of the ladle nozzle 5 and each discharge outlet 10-1 nearer to the center of the tundish.
- the height A of the inner and outer dams 15, 15 and 8, 8 is higher than that defined above, the molten steel will be retained for a longer time than required so that the powder once uniformly dispersed in the molten steel will settle and accumulate on the bottom of the tundish. Conversely, if the height A is lower than defined, undissolved powder will flow into the discharge outlets 10-1 and 10-2.
- Fig. 16 depicts an embodiment in which a gas ejector 7 is provided in the center portion between the dams 8, 8 and passage zones 16, 16 for the low melting metal are provided downstream of the dams 8, 8.
- the same numerals are used to indicate the same means.
- tundish bricks which has been in use for a long time and found that Pb or Bi had passed through the joint of the tuyere of the nozzle, the upper tuyere, the lower tuyere and the upper nozzle and their pores, and had flown into the nozzle, resulting in the formation of huge Pb or Bi.
- Figs. 16, 17 and 18 show the structure of a tundish designed to cope with this phenomenons.
- a passage zone 16 comprising porous bricks, slotted safety bricks, and a slotted steel jacket is provided downstream of each of a pair of dams.
- Fig. 19 shows an enlarged view of the passage zone for undissolved powder.
- This passage zone is provided between an upper nozzle 27 constituting a part of a discharge outlet 10 and the position at which the molten steel is poured into the tundish and comprises porous brick 31, slotted safety brick 32 and a slotted steel jacket 33 instead of wear brick 22, safety brick 23, and a steel jacket 24.
- the top face of the porous brick 31 is a little lower than the top face of the wear brick 22, while the top face of the wear brick 22 and the coating material 21' thereon are inclined by such an angle that the undissolved powder remaining on the bottom of the tundish will be easily settled into the porous brick 31.
- the safety brick 32 is fixed in place between the porous brick 31 and the steel jacket 33 by making use of safety brick with upper and lower slots. It is preferred that the steel jacket 33 is positioned at a lower level than the steel jacket 24 so that the undissolved powder which has penetrated between the safety brick 23 and the steel jacket 24 can easily pass therebetween.
- a pool box 34 for holding the undissolved powder of low melting metal is provided under the steel jacket 33.
- the penetrating undissolved powder is prevented from moving toward the upper nozzle 27, and is carried to enter the pool box 34 by a steel seal plate 35 provided between the porous brick 31, the safety brick 32, the steel jacket 33 and the upper nozzle 27.
- the lengths of the porous brick 31, the safety brick 32, and the steel jacket 33 are preferred to be 0.1-1.0 times the width of the tundish around the upper nozzle 27 in the width direction of the tundish.
- the porous brick 31 may be of the ordinary kind which easily passes gas but is resistant to the penetration of molten steel. The undissolved powder will easily penetrate the porous brick and collect in the pool box.
- the stream of molten steel from the ladle is prevented from passing directly toward the upper nozzle 27 shown in an enlarged view in Fig. 19 by the shroud 14 and the dams 8, 8 and the undissolved powder segregated from the molten steel settles on the bottom of the tundish.
- a small aperture is made at the bottom of each dam 8, and the undissolved powder which has settled on the bottom of the tundish passes through the small aperture and moves nearer the upper nozzle 27.
- the undissolved powder which has passed through the dam 8 is carried to the porous brick 31 along the top face of the inclined coating material 21'. The undissolved powder then passes through the porous brick 31, the safety brick 32 and the steel jacket 33 and is collected in the pool box 34.
- the steel seal plate 35 for preventing the undissolved powder from being discharged with the molten steel is provided around the upper tuyere 25 and a lower tuyere 26 in order to completely prevent the undissolved powder from entering the upper nozzle 27.
- the steel seal plate 35 may be positioned between the upper nozzle 27 and the upper and lower tuyeres 25, 26.
- the undissolved powder For collecting the undissolved powder continuously, it is possible to provide outside heating means on the steel jacket 33 and on the pool box 34. When no heating means are provided, the undissolved powder is collected after completion of casting by removing the pool box 34 from the machine.
- the top face of the porous plug is positioned at a lower level than the upper tuyere 25 to prevent Pb on the porous brick 31 from overflowing the top face of the tuyere owing to the weak metal flow from the small aperture of the dam 8.
- Recovery means for the indissolved powder consisting of the inclined coating material 21', the porous brick 31, the safety brick 32, the steel jacket 33, the pool box 34, and the steel seal plate 35 can also be provided with good effect at other positions on the bottom of the tundish.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
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- Treatment Of Steel In Its Molten State (AREA)
Description
- The present invention relates to a tundish for continuous casting of a free cutting molten steel added with Pb or Bi in order to promote the melting and dispersion thereof according to the preamble of claim 1.
- A free-cutting steel is produced by adding a machinability element to the molten steel, Pb, Bi, etc. are known as machinability elements.
- However, there is a great difference between the melting points of Pb and Bi and that of steel, and further, both Pb and Bi have a higher specific gravity than steel. As a result, in continuous casting undissolved Pb or Bi flows from the tundish into the mold and becomes so unevenly distributed in the continuously cast steel that it forms huge inclusions therein, degrading the quality of the continuously cast product.
- To deal with this problem, Japan examined patent application (referred to as Kokoku) No. 48(1973)-14524 proposes surrounding the ladle outlet with a dam to prevent the flow of Pb or Bi. Another Japan unexamined utility model application (referred to as Utility Model Kokai) No. 54(1979)-35715 proposes providing the bottom of the tundish with a dam to prevent undissolved alloy and nonmetallic inclusions from flowing into the mold.
- According to another Kokai No. 59(1984)-56562, it is proposed to greatly improve the addition yield of Pb by reducing the rate of addition thereof into the ladle so as to remarkably decrease the amount of Pb setting at the bottom of the ladle.
- The methods generally used for adding a low melting alloy, a ferro-alloy or the like into the steel melt are that of adding the alloy to the steel melt being discharged from the steel converter and that of adding it directly into the ladle. In another Kokai No. 45(1979)-31013 and the Kokai No. 54(1979)-31035, a shroud is provided over the whole length of the molten steel flow downwardly from the ladle to the tundish and an inflow-pipe is installed at its forward end for introduction of PB onto the molten steel level in the tundish at an intermediate point of the vertical length of the shroud.
- Further in Kokoko No. 54(1979)-36574, a shroud is provided to surround the lower part of the molten steel flowing down from the ladle, and a dam is provided at the lower part thereof as immersed into the molten steel with the tundish. A steel purifying agent is droppingly added within the immersed dam.
- A prime object of the present invention is to provide a tundish for use in continuous casting in which undissolved Pb and Bi in the molten steel are prevented from flowing into the mold.
- Another object of the invention is to provide a tundish in which the Pb and Bi dissolution yield is greatly improved by forming a large circulation current of the molten steel so as to control the behaviour of the Pb and Bi.
- These objects are achieved with a tundish having the features of the claim 1.
- Figure 1 is a front sectional view showing a typical embodiment of the present invention.
- Fig. 2 is a plan view along line X-X of Fig. 1.
- Fig. 3 is a front sectional view of another embodiment of the invention.
- Fig. 4 is a plan view along line X-X of Fig. 3.
- Fig. 5 is a front sectional view of another embodiment of the invention.
- Fig. 6 is a plan view along line X-X of Fig. 5.
- Fig. 7 is a front sectional view of another embodiment of the invention.
- Fig. 8 is a plan view along line X-X of Fig. 7.
- Fig. 9 is a plan view of a modification of the embodiment of Fig. 7.
- Fig. 10 is front sectional view of another embodiment of the invention.
- Fig. 11 is a plan view alog line X-X of Fig. 10.
- Fig. 12 is a front sectional view of another embodiment of the invention.
- Fig. 13 is a plan view along line X-X of Fig. 12.
- Fig. 14 is a front sectional view of another embodiment of the invention
- Fig. 15 is a plan view along line X-X of Fig. 14.
- Fig. 16 is a front sectional view of still another embodiment of the invention.
- Fig. 17 is a similar view along the line X-X of Fig. 16.
- Fig. 18 is a similar plan view along the line Y-Y of Fig. 17.
- Fig. 19 is a partial enlarged view of the invention.
- In accordance with the present invention, a tundish is provided with a molten steel teeming zone (referred to as teeming zone hereinafter) into which Pb or Bi (referred to as a low melting metal hereinafter) is added. The teeming zone is formed in the middle region of the tundish. A dispersing means which stirs the molten steel so as to promote uniform dispersion of the low melting metal is provided along a runner through which the molten steel runs from the teeming zone to a discharge outlet.
- As a dispersing means an ejector having dispersing capabilities may be provided at the bottom of the tundish from which an inert gas such as Ar, N2 etc, is ejected to stir the molten steel by gas bubbling action.
- In addition, at least one dam is provided downstream of the dispersing means in order to prevent the low melting metal from flowing into the discharge outlet for the molten steel.
- In Figs. 1-2, there are shown a ladle 1, a
ladle nozzle 5 and afeed pipe 9 for the low melting metal. Themain body 3 of a tundish 2 is provided with acover 6, anddams gas ejectors main body 3 is further provided withdischarge outlets 10. - A teeming zone is formed immediately below the
nozzle 5, and a dispersing zone is formed between thegas ejectors dams - Fig. 3 shows another embodiment of the invention, wherein the
main body 3 of the tundish is formed with a projecting part4 (referred to as a T-type tundish hereinafter), and theladle nozzle 5 is positioned nearly at the centre a of the projectingpart 4. In this embodiment, the teeming zone is defined by the position a of theladle nozzle 5 and the projectingpart 4, and the dispersion zone is formed between thedams single gas ejector 7. - Fig. 5 shows another embodiment of the invention, wherein the teeming zone is defined by two
inner weirs cover 6 so as to enclose the center area of the tundish 2. The molten steel is teemed in the center portion. The reach inner weirs should be long enough to pass into the molten steel but not so long as to reach the base of the tundish. A convex portion 11, high in the middle and tapering off on both sides, is provided within the teeming zone surrounded by the inner weirs. - Two
outer weirs cover 6 of the tundish outside the teeming zone, and thegas ejectors inner weirs 12 and theouter weirs 13. - The gas used is Ar or N2, and the gas ejector is preferably a porous plug. The
outer weirs 13 should preferably be about the same length as the inner ones but are still effective even if longer or shorter. - In addition,
dams outer weirs dams gas ejectors inner weirs dams steel discharge outlets dams - The forward tip of the
feed pipe 9 is directed to the stream of molten steel passing from the ladle 1 to the tundish 2 and so used to add a low melting metal to the molten steel in the form of a powder. - When the molten steel flows from the ladle into the teeming zone, the powder supplied by the
feed pipe 9 is entrained by the descending steel stream due to its falling energy. As the entrained powder is surrounded by theweirs - In the dispersion zones, the molten steel is vigorously stirred by the bubbling action of the gas from the gas ejectors. By such stirring, the powder is dissolved and dispersed in the molten steel.
- Since the dispersion zones are surrounded by the
inner weirs outer weirs - If, for some reason, some part of the powder is neither dissolved nor dispersed in the molten steel, this remaining powder will be prevented from flowing into the continuous casting mold via the
discharge outlet 10 of molten steel by thedams - Another embodiment of the invention is shown in Fig. 7. In this embodiment, the
nozzle 5 is provided under the ladle 1, and ashroud 14 is provided to extend downward from thecover 6 of thetundish 2 so as to surround the lower part of thenozzle 5. - The upper end of the
shroud 14 is flush with thecover 6. Thefeed pipe 9 is provided to open into the space between theladle nozzle 5 and theshroud 14. The lower end of theshroud 14 is immersed into the molten steel in the tundish. As illustrated in Fig. 8, theshroud 14 is of oblong shape in horizontal section and surrounds theladle nozzle 5. This embodiment has asingle gas ejector 7. - In Figs. 8-9, the
ladle nozzle 5 is a sliding nozzle movable between two positions 5-1 and 5-2 separated by a distance I. In the case of a stationary nozzle, I =0. - Defining the width and length of the shroud and the depth of immersion thereof in the molten steel in the tundish as A, B and C (all in mm), respectively, the outside diameter and sliding distance of the nozzle as d and I (in mm), respectively, and the depth of the molten steel as h (in mm), the optimum dimensions of the shroud fall within the following ranqe.
- If the above conditions are not satisfied, for instance, if the width A of the shroud should be less than three times the diameter d of the nozzle, the molten steel from the nozzle will splatter on the inside wall of the shroud, increasing the amount of skull adhering thereto and consequently making it impossible to add the powder to the molten steel.
- Moreover, if the width A of the shroud exceeds six times the diameter d of the nozzle or the length B of the shroud exceeds I + 100 mm, the stirring action of the molten steel in the shroud is so reduced that almost no stirring-in of the powder is attained.
- Further, when the depth of immersion C is less than 0.5 times the depth of the molten steel h, the molten steel is dispersed out of the shroud in a short time and, and as a result, mixing of the powder into the molten steel is insufficient.
- On the other hand, if the depth of immersion C exceeds 0.8 times the depth of the molten steel h, the solid powder which has been added, stirred and mixed remains in the shroud for a long time, preventing sufficient diffusion of the powder into the tundish.
- With the arrangement according to the embodiment described above, when the molten steel in the ladle 1 passes into the
tundish 2 via thenozzle 5, the molten steel stream from the nozzle is vigorously stirred within theshroud 14. Therefore, when the powder is added thereto, it is mixed and dispersed in the stirred stream of molten steel, and thereafter the molten steel is dispersed from the bottom of the shroud to the left and right regions of thetundish 2. - While the embodiments of the present invention described in the foregoing are for use with two strands, Fig. 10, 11 depict a tundish of the type shown in Fig. 7 for use with one strand. Numerals 7-1, 7-2 and 7-3 designate gas ejectors.
- Figs. 12-15 illustrate further embodiments of this invention.
- In the embodiment shown in Fig. 12, a pair of
inner dams outer dams tundish 2. Theladle nozzle 5 is positioned between theinner dams outer dam 8 is positioned between one of the inner dams and one of a pair ofdischarge outlets 10. - As shown in Fig. 13, the
inner dams outer dams - Figs 14 to 15 show a T-type tundish to which the principle of the invention is applied. Here, a third
inner dam 15 is provided so as to partition off the projectingpart 4 of the tundish. - In the embodiments of Figs. 12-15, the following relationships should be satisfied.
inner dams outer dams inner dam 15 and the center of theladle nozzle 5; C is the distance between eachouter dam 8 and the center of theladle nozzle 5; E is the depth of the molten steel; and F is the distance between the center of theladle nozzle 5 and each discharge outlet 10-1 nearer to the center of the tundish. - If the height A of the inner and
outer dams - If the distances B and C are too great, the molten steel will be retained for a longer time than required, and if too small, undissolved powder will escape.
- In Figs. 14-15, the molten steel from the
ladle nozzle 5 temporarily remains within theinner dams inner dams - Still another embodiment of the invention will be described in connection with Figs. 16-19.
- Fig. 16 depicts an embodiment in which a
gas ejector 7 is provided in the center portion between thedams passage zones dams - Experiments show that in the continuous casting of steel containing a low melting metal, such as Pb or Bi, which has a greater specific gravity and a lower melting point than steel, if the low melting metal remains in the molten steel for a prolonged time, it becomes impossible to prevent its penetration and passage through of the pores and joints of refractory bricks of the type now in general use in the industry.
- After the use, the inventors examined tundish bricks which has been in use for a long time and found that Pb or Bi had passed through the joint of the tuyere of the nozzle, the upper tuyere, the lower tuyere and the upper nozzle and their pores, and had flown into the nozzle, resulting in the formation of huge Pb or Bi.
- Figs. 16, 17 and 18 show the structure of a tundish designed to cope with this phenomenons.
- As an effective means for preventing the flow of settled low melting metals into the discharge outlet for the molten steel, a
passage zone 16 comprising porous bricks, slotted safety bricks, and a slotted steel jacket is provided downstream of each of a pair of dams. - Fig. 19 shows an enlarged view of the passage zone for undissolved powder. This passage zone is provided between an
upper nozzle 27 constituting a part of adischarge outlet 10 and the position at which the molten steel is poured into the tundish and comprisesporous brick 31, slottedsafety brick 32 and a slottedsteel jacket 33 instead ofwear brick 22,safety brick 23, and asteel jacket 24. - The top face of the
porous brick 31 is a little lower than the top face of thewear brick 22, while the top face of thewear brick 22 and the coating material 21' thereon are inclined by such an angle that the undissolved powder remaining on the bottom of the tundish will be easily settled into theporous brick 31. Thesafety brick 32 is fixed in place between theporous brick 31 and thesteel jacket 33 by making use of safety brick with upper and lower slots. It is preferred that thesteel jacket 33 is positioned at a lower level than thesteel jacket 24 so that the undissolved powder which has penetrated between thesafety brick 23 and thesteel jacket 24 can easily pass therebetween. Apool box 34 for holding the undissolved powder of low melting metal is provided under thesteel jacket 33. - The penetrating undissolved powder is prevented from moving toward the
upper nozzle 27, and is carried to enter thepool box 34 by asteel seal plate 35 provided between theporous brick 31, thesafety brick 32, thesteel jacket 33 and theupper nozzle 27. - The lengths of the
porous brick 31, thesafety brick 32, and thesteel jacket 33 are preferred to be 0.1-1.0 times the width of the tundish around theupper nozzle 27 in the width direction of the tundish. - The
porous brick 31 may be of the ordinary kind which easily passes gas but is resistant to the penetration of molten steel. The undissolved powder will easily penetrate the porous brick and collect in the pool box. - In the embodiment shown in Fig. 16, the stream of molten steel from the ladle is prevented from passing directly toward the
upper nozzle 27 shown in an enlarged view in Fig. 19 by theshroud 14 and thedams dam 8, and the undissolved powder which has settled on the bottom of the tundish passes through the small aperture and moves nearer theupper nozzle 27. In Fig. 19, the undissolved powder which has passed through thedam 8 is carried to theporous brick 31 along the top face of the inclined coating material 21'. The undissolved powder then passes through theporous brick 31, thesafety brick 32 and thesteel jacket 33 and is collected in thepool box 34. Thesteel seal plate 35 for preventing the undissolved powder from being discharged with the molten steel is provided around theupper tuyere 25 and alower tuyere 26 in order to completely prevent the undissolved powder from entering theupper nozzle 27. Alternatively, thesteel seal plate 35 may be positioned between theupper nozzle 27 and the upper andlower tuyeres - For collecting the undissolved powder continuously, it is possible to provide outside heating means on the
steel jacket 33 and on thepool box 34. When no heating means are provided, the undissolved powder is collected after completion of casting by removing thepool box 34 from the machine. - The top face of the porous plug is positioned at a lower level than the
upper tuyere 25 to prevent Pb on theporous brick 31 from overflowing the top face of the tuyere owing to the weak metal flow from the small aperture of thedam 8. - Recovery means for the indissolved powder, consisting of the inclined coating material 21', the
porous brick 31, thesafety brick 32, thesteel jacket 33, thepool box 34, and thesteel seal plate 35 can also be provided with good effect at other positions on the bottom of the tundish.
Claims (6)
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP191948/84U | 1984-12-18 | ||
JP1984191948U JPH024755Y2 (en) | 1984-12-18 | 1984-12-18 | |
JP23534/85U | 1985-02-22 | ||
JP1985023534U JPS61152369U (en) | 1985-02-22 | 1985-02-22 |
Publications (4)
Publication Number | Publication Date |
---|---|
EP0186852A2 EP0186852A2 (en) | 1986-07-09 |
EP0186852A3 EP0186852A3 (en) | 1987-05-06 |
EP0186852B1 EP0186852B1 (en) | 1989-05-17 |
EP0186852B2 true EP0186852B2 (en) | 1992-04-29 |
Family
ID=26360909
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP85116118A Expired - Lifetime EP0186852B2 (en) | 1984-12-18 | 1985-12-17 | Tundish for continuous casting of free cutting steel |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0186852B2 (en) |
AU (1) | AU559525B2 (en) |
DE (1) | DE3570194D1 (en) |
ES (1) | ES8700589A1 (en) |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4711429A (en) * | 1986-08-29 | 1987-12-08 | Usx Corporation | Tundish for mixing alloying elements with molten metal |
GB8703717D0 (en) * | 1987-02-18 | 1987-03-25 | Injectall Ltd | Injecting gas into metal melts |
IN168760B (en) * | 1987-04-10 | 1991-06-01 | Injectall Ltd | |
US5004495A (en) * | 1990-02-05 | 1991-04-02 | Labate M D | Method for producing ultra clean steel |
ZA935963B (en) * | 1992-12-28 | 1994-03-15 | Inland Steel Co | Tundish for molten alloy containing dense undissolved alloying ingredient |
FR2756762B1 (en) * | 1996-12-11 | 1998-12-31 | Ugine Savoie Sa | SUPPLY TANK INTENDED TO RETAIN MELTED METAL AND IN PARTICULAR STEEL |
CN103990787B (en) * | 2014-05-16 | 2016-07-06 | 莱芜钢铁集团有限公司 | A kind of for removing the device and method of molten steel inclusion in continuous casting production |
KR101834216B1 (en) * | 2016-06-08 | 2018-03-05 | 주식회사 포스코 | Molten material processing apparatus and processing method |
AR109299A1 (en) | 2016-08-08 | 2018-11-14 | Vesuvius Crucible Co | IMPACT PLATE |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS4814524B1 (en) * | 1969-07-28 | 1973-05-08 | ||
DE1945499B2 (en) * | 1969-09-09 | 1973-01-18 | DEVICE FOR CASTING ALUMINUM KILLED STEELS IN RIBBON AND SLAG FOR USE IN SUCH A DEVICE | |
DE2119664B2 (en) * | 1971-04-22 | 1975-01-16 | Kloeckner-Werke Ag, 4100 Duisburg | Process for separating Al deep 2 O deep 3 inclusions in the continuous casting of steel in the tundish |
AR206969A1 (en) * | 1975-06-17 | 1976-08-31 | Foseco Trading Ag | LAUNDRY TANK WITH LANDFILLS |
JPS5431013A (en) * | 1977-08-12 | 1979-03-07 | Kawasaki Steel Co | Method of adding calcium metal or calcium alloy into molten steel within continuous casting tandish |
JPS5814034Y2 (en) * | 1977-08-15 | 1983-03-18 | 日本鋼管株式会社 | Tandish Weir |
-
1985
- 1985-12-17 DE DE8585116118T patent/DE3570194D1/en not_active Expired
- 1985-12-17 EP EP85116118A patent/EP0186852B2/en not_active Expired - Lifetime
- 1985-12-17 ES ES85550062A patent/ES8700589A1/en not_active Expired
- 1985-12-18 AU AU51439/85A patent/AU559525B2/en not_active Ceased
Also Published As
Publication number | Publication date |
---|---|
EP0186852A2 (en) | 1986-07-09 |
EP0186852B1 (en) | 1989-05-17 |
EP0186852A3 (en) | 1987-05-06 |
ES8700589A1 (en) | 1986-10-16 |
AU5143985A (en) | 1986-06-26 |
AU559525B2 (en) | 1987-03-12 |
DE3570194D1 (en) | 1989-06-22 |
ES550062A0 (en) | 1986-10-16 |
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