CN114040823A - Nozzle structure on tundish and continuous casting method - Google Patents
Nozzle structure on tundish and continuous casting method Download PDFInfo
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- CN114040823A CN114040823A CN202080046023.XA CN202080046023A CN114040823A CN 114040823 A CN114040823 A CN 114040823A CN 202080046023 A CN202080046023 A CN 202080046023A CN 114040823 A CN114040823 A CN 114040823A
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- 238000009749 continuous casting Methods 0.000 title claims abstract description 23
- 238000000034 method Methods 0.000 title claims abstract description 13
- 230000002093 peripheral effect Effects 0.000 claims abstract description 18
- 229910000831 Steel Inorganic materials 0.000 claims description 45
- 239000010959 steel Substances 0.000 claims description 45
- 238000005266 casting Methods 0.000 claims description 25
- 239000000463 material Substances 0.000 claims description 15
- 239000000853 adhesive Substances 0.000 claims description 6
- 230000001070 adhesive effect Effects 0.000 claims description 6
- 230000000149 penetrating effect Effects 0.000 claims description 2
- 239000012535 impurity Substances 0.000 abstract description 3
- 239000007789 gas Substances 0.000 description 85
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 6
- 230000007547 defect Effects 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 238000007664 blowing Methods 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- 239000011261 inert gas Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 238000004088 simulation Methods 0.000 description 3
- 210000004916 vomit Anatomy 0.000 description 3
- 230000008673 vomiting Effects 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000014509 gene expression Effects 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 241000428845 Cultellus Species 0.000 description 1
- 229910000655 Killed steel Inorganic materials 0.000 description 1
- 229910000805 Pig iron Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000009795 derivation Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 238000000611 regression analysis Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
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Classifications
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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
- B22D41/50—Pouring-nozzles
- B22D41/58—Pouring-nozzles with gas injecting means
-
- 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
-
- 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
-
- 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
-
- 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
- B22D41/14—Closures
- B22D41/16—Closures stopper-rod type, i.e. a stopper-rod being positioned downwardly through the vessel and the metal therein, for selective registry with the pouring opening
-
- 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
- B22D41/50—Pouring-nozzles
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Continuous Casting (AREA)
- Valve Housings (AREA)
- Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
Abstract
The invention provides a nozzle structure on a tundish and a continuous casting method, which can float impurities in the tundish. Specifically, in the present invention, a collar (12) having a larger outer shape than the upper end portion of the upper nozzle of the tundish is provided on a part or the entire periphery of the upper end portion of the upper nozzle (11) of the tundish, and one or more air discharge holes (13a) are provided on any one or more of the lower surface, the outer peripheral surface, the upper surface, and the outer peripheral surface of the upper nozzle (11) of the tundish below the collar (12). In the tundish upper nozzle structure, the length L is adjusted, whereby substantially all of the gas can be floated, or the flow rate of the gas toward the lower part of the inner bore side and the floating amount can be adjusted.
Description
Technical Field
The present invention relates to a nozzle structure on a tundish having a gas blowing function and a continuous casting method.
Background
In continuous casting of steel, an operation of blowing gas from a nozzle on a tundish is often performed. The gas is blown mainly for the following purpose.
(1) By flowing the gas bubbles downward from the inner bore of the nozzle on the tundish, the adhesion of the inclusions to the inner bore surface of the nozzle on the tundish or the nozzle below the tundish, or the clogging of the inner bore due to the adhesion of the inclusions can be suppressed.
(2) The flow pattern of the molten steel in the mold is controlled from below the nozzle on the tundish.
(3) The impurities float upwards below the nozzle on the casting head or in the casting mould.
(4) The impurities float upwards in the casting head.
These can have an effect on the stability and productivity of the casting operation, and the quality of the cast slab.
In the above (1) to (4), gas discharge from the nozzle on the tundish has been conventionally performed in various forms.
Mainly in view of the above (1) to (3), for example, patent document 1 proposes a configuration in which a porous portion for gas discharge is provided in an inner hole of a nozzle on a tundish, and an annular collar portion of an annular refractory provided on an outer periphery of an upper end portion of the nozzle on the tundish covers an upper portion of the nozzle on the tundish. Thus, the gas can be reliably supplied to the inner hole of the nozzle on the tundish.
Further, patent document 2 proposes a stopper receiving nozzle at the bottom of a tundish, which is characterized in that a porous refractory is provided on the upper and lower molten steel contact surfaces of the nozzle at the contact portion with the stopper, and argon gas can be independently blown out from each porous refractory, in order to prevent inclusions or pig iron from adhering to the vicinity of the contact portion between the stopper and the upper nozzle, and to obtain a good cast slab by performing a stable flow rate control.
Further, with a view to the above (4), patent document 3 proposes a continuous casting method in which a nozzle is provided at the bottom of a tundish, and an inert gas is blown from an annular upper porous refractory provided at the upper part of the nozzle and an inert gas is blown from an annular lower porous refractory provided at the lower part of the nozzle. Thus, the upper porous refractory may be blown with inert gas towards the molten steel of the tundish and the lower porous refractory may be blown with inert gas towards the opening of the nozzle.
Patent document
Patent document 1: japanese patent laid-open publication No. 2003-220450
Patent document 2: japanese laid-open patent publication No. 6-297118
Patent document 3: japanese patent laid-open publication No. 2016-
Disclosure of Invention
In order to improve the quality of the cast slab, it is also important to float the inclusions in the tundish in the above (4). The balance of the above (1) to (3) and (4) is a property determined appropriately according to individual operation conditions (including know-how), steel grade, quality target, and the like.
However, in the gas blowing method and the like of the related art such as the above patent document, it is known that most of the blown gas flows toward the inner hole side of the nozzle on the tundish, and the gas cannot be floated upward, that is, in the molten steel in the tundish.
Further, in order to float up the inclusions in the tundish in the above-mentioned (4), there is also a method of blowing gas into the tundish at an arbitrary position other than the upper nozzle of the tundish at the bottom of the tundish.
However, in order to blow gas into the tundish at an arbitrary position other than the upper nozzle of the tundish at the bottom of the tundish, a dedicated facility is required, which increases initial cost and running cost, and also increases the risk of breakout during handling. Further, the method is indicated to be insufficient in the effect of removing inclusions in the molten steel.
From this viewpoint, in order to remove inclusions by gas in the tundish, it is preferable to form an upward floating flow of gas into the molten steel in the tundish by using the tundish upper nozzle and to adjust the ratio of the upward floating flow to the gas.
The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a tundish nozzle structure and a continuous casting method, which can arbitrarily adjust the balance between the gas flow rate at or below the inner hole of the tundish nozzle and the gas flow rate floating in the tundish (from the tundish upper nozzle to the upper side) by floating all the gas blown from a specific portion of a nozzle in a tundish (from the tundish upper nozzle to the upper side) in a manner such that the gas is blown from the tundish upper nozzle.
In addition, since there are various discharge positions, forms of discharge holes such as porous bodies and through holes, the number of discharge holes, and the like in a single tundish nozzle, the "total gas blown from a specific portion of the nozzle" in the present invention means one gas outflow portion, in other words, "total gas discharged from one through hole, or total gas discharged from a merged portion of very small discharge holes, which is a portion where a plurality of bubbles immediately after discharge meet and form one bubble even with a plurality of discharge holes including a porous body or the like, and can be said to form a very small merged portion of one bubble, not the total gas discharged from a single tundish nozzle.
The present inventors have found that, as in the above-mentioned patent document, the reason why most of the gas blown in from the vicinity of the upper end of the nozzle on the tundish flows to the inner hole side of the nozzle on the tundish and the gas cannot be floated upward, that is, in the molten steel in the tundish is that the molten steel flow to the inner hole of the nozzle in the vicinity of the gas spouting hole in the vicinity of the upper end of the nozzle on the tundish forms a main body and the molten steel flow is stronger than the floating flow of the gas bubbles.
That is, the present invention is a nozzle structure on a tundish and a continuous casting method using the nozzle structure on a tundish, and is characterized in that in order to make the upward flow of bubbles stronger than the molten steel flow to the inner hole of the tundish, gas is discharged at a position where the flow velocity of the molten steel to the inner hole of the tundish is smaller than the upward flow velocity of the bubbles, and the balance between the gas flow rate to the inner hole of the tundish and the upward gas flow rate can be adjusted.
Specifically, the present invention relates to the following 1 to 11 tundish nozzle structures and a continuous casting method of 12.
1. A nozzle structure on a tundish is characterized in that a jaw-like body larger than the outer shape of the upper end part of a nozzle on the tundish is provided on a part of or the whole periphery of the upper end part of the nozzle on the tundish, and one or more air discharge holes are provided on any one or more surfaces of the lower surface, the outer peripheral surface, the upper surface and the outer peripheral surface of the nozzle on the tundish below the jaw-like body.
2. The structure of a nozzle on a tundish according to claim 1, wherein the gas discharge hole of the flange is a hole penetrating an upper surface from an end of the gas flow path which is a space in the flange or a lower surface of the flange.
3. The structure of the above-described tundish nozzle according to claim 1 or 2, wherein the lower surface of the flange is provided with one or more grooves through which gas can pass.
4. The structure of an on-tundish nozzle according to claim 1 or 2, wherein a space through which gas can pass is provided in a part or the whole of the lower surface of the flange in a state in which the on-tundish nozzle structure is mounted on the tundish.
5. The nozzle-on-tundish nozzle structure according to any one of the preceding 1 to 4,
the nozzle structure on a tundish is used for continuous casting of steel, wherein the flow rate of molten steel is controlled by a stopper rod,
a length L (mm) from a vertical position of an inner hole surface of a lower end of the nozzle on the tundish to an upper discharge hole or an outer peripheral surface of the jaw satisfies the following formula 1,
L≧-1.875M2+26.332M-0.3929 … formula 1
Here, M: casting speed (t/min).
6. The nozzle-on-tundish nozzle structure according to any one of the preceding 1 to 4,
the nozzle structure on a tundish is used for continuous casting of steel, wherein the flow rate of molten steel is controlled by a stopper rod,
a length L (mm) from a vertical position of an inner hole surface of a lower end of the nozzle on the tundish to an upper discharge hole or an outer peripheral surface of the jaw satisfies the following formula 2,
L<-1.875M2+26.332M-0.3929 … formula 2
Here, M: casting speed (t/min).
7. The structure of any one of claims 1 to 5, wherein a length L (mm) from a vertical position of an inner hole surface of a lower end of the upper nozzle to the gas discharge hole or the outer peripheral surface of the upper surface of the collar is 60mm or more.
8. The structure of any one of claims 1 to 7, wherein the collar engages the upper tundish nozzle.
9. The structure of the nozzle-on-tundish according to claim 8, wherein the flange and the nozzle-on-tundish are joined by a screw, a snap-fit structure, or an adhesive material.
10. The above-tundish nozzle structure according to any one of claims 1 to 7, wherein the collar is fitted to an outer periphery of the above-tundish nozzle and bonded to a tuyere or a tundish bottom refractory layer adjacent to the above-tundish nozzle.
11. The structure of an on-tundish nozzle according to claim 10, wherein the flange and the tuyere or the refractory layer at the bottom of the tundish are joined by a screw, a snap-fit structure, or an adhesive.
12. A continuous casting method using the tundish upper nozzle structure according to any one of the above 1 to 4,
the nozzle structure on a tundish is used for continuous casting of steel, the flow rate of molten steel is controlled by a stopper rod,
a length L (mm) from a vertical position of an inner hole surface of a lower end of a nozzle on the tundish to a spitting hole or an outer peripheral surface of an upper surface of the jaw-like material is set to be equal to or more than a boundary length LB (mm) satisfying the following formula 3 so as to float substantially all of the gas, or is set to be smaller than the boundary length LB (mm) so as to adjust a flow rate and a floating amount of the gas facing a lower part of the inner hole side of the gas,
LB＝-1.875M2+26.332M-0.3929 … formula 3
Here, M: casting speed (t/min).
According to the present invention, since the flange-like member larger than the outer shape of the upper end portion of the upper nozzle of the tundish is provided on a part of or the entire periphery of the upper end portion of the upper nozzle of the tundish, the gas can be guided to the outer peripheral side of the upper nozzle of the tundish, that is, to the region where the flow rate of the molten steel to the inner hole is small, and the gas can be directed upward from the vicinity thereof. This makes it possible to float the gas in the tundish, thereby achieving an effect of floating the inclusions in the tundish. Thereby improving the quality of the cast piece.
Further, the flow rate of the gas to the lower side of the inner hole of the nozzle and the floating flow rate into the tundish can be arbitrarily adjusted by arbitrarily adjusting the length (L) from the vertical position of the lower end of the inner hole of the flange-like material larger than the outer shape of the nozzle on the tundish to the gas discharge hole or the portion which is released upward after flowing along the flange-like material to the gas discharge portion, according to individual operations or the like.
Drawings
Fig. 1 is a schematic cross-sectional view showing a main part of a nozzle structure on a tundish, which is an embodiment of the present invention.
Fig. 2 is a diagram in which the right side of the above-described formulas 1 and 2 is patterned.
Fig. 3 is a graph showing the results of gas behavior analysis on the nozzle structure on the tundish of fig. 1.
Description of the symbols
10-a nozzle structure on a tundish; 11-a nozzle on the tundish; 11 a-inner bore; 11 b-inner bore face; 12-a cultellus; 13a, 13 b-vomit holes; 20-a stopper rod; 30-a tundish; 31-tuyere; 32-tundish bottom refractory layer; s-space.
Detailed Description
Fig. 1 shows a main part of a nozzle structure on a tundish according to an embodiment of the present invention.
The tundish upper nozzle structure 10 of the present embodiment is used for continuous casting of steel, in which the flow rate of molten steel is controlled by the stopper rod 20, and the tundish upper nozzle 11 includes a flange 12 having a larger outer diameter than the outer shape (outer diameter) of the tundish upper nozzle 1 over the entire circumference of the upper end portion thereof. The upper tundish nozzle assembly 10 of the present embodiment includes a plurality of (6 in the circumferential direction at equal intervals) gas discharge holes 13a on the outer circumferential surface of the upper tundish nozzle 11 below the flange 12. The upper tundish nozzle structure 10 of the present embodiment further includes a plurality of (24 at equal intervals in the circumferential direction) gas discharge holes 13b in the upper end surface of the upper tundish nozzle 11.
As shown in fig. 1, the upper tundish nozzle assembly 10 includes a space S through which a gas can pass in a part or the whole of the lower surface of the flange 10 in a state in which the upper tundish nozzle assembly is mounted on the tundish 30 (molten steel is present in the space because the tundish is filled with molten steel during casting).
As described above, by providing the flange 12 to the upper tundish nozzle assembly 10 according to the present embodiment, the gas can be guided to the outer peripheral side of the upper tundish nozzle 11, that is, to the region (the direction of the arrow B) where the flow rate of the molten steel (the direction of the arrow a) to the inner bore 11a is small, and can be directed upward from the vicinity thereof. This makes it possible to float the gas in the tundish 30, thereby obtaining an effect of floating the inclusions in the tundish 30. Thereby improving the quality of the cast piece.
The inventors have found that, in such a tundish-upper nozzle structure 10, the ratio of the flow rate of the gas downward toward the inner hole 11a to the amount of the gas floating up into the tundish 30 largely depends on the length l (mm) and the casting speed M (t/min) shown in fig. 1. Here, the length L shown in fig. 1 is a length from a vertical position of the inner hole surface 11b of the lower end of the nozzle 11 on the tundish to the discharge hole or the outer peripheral surface of the upper surface of the collar 12, and the casting speed M (t/min) is synonymous with the amount of molten steel passing therethrough.
The reason why the length L is set to be from the vertical position of the inner bore surface 11b at the lower end of the nozzle 11 on the tundish is that although the outer periphery of the nozzle on the tundish or the vicinity of the upper end thereof may have various shapes, if the casting speed is the same, the position of the inner bore surface at the lower end (which is substantially the same as the inner bore diameter) hardly changes, that is, there is no great difference in the speed of the molten steel flowing into the inner bore, and in the case of stopper control, the position of the fitting portion thereof is substantially the same radial position corresponding to the diameter of the inner bore.
That is, the present inventors have found that when the length l (mm) satisfies the following formula 1, substantially all of the gas can be floated within the tundish, and when the length l (mm) satisfies the following formula 2, the flow rate of the gas toward the lower portion of the inner bore side and the floating amount can be adjusted.
L≧-1.875M2+26.332M-0.3929 … formula 1
L<-1.875M2+26.332M-0.3929 … formula 2
As described above, the control of the inner hole side or the floating rate of the gas in the present invention is performed for each gas discharged from each discharge hole.
Therefore, when the upper surface of the blade-like member, which is a reference for determining one of the lengths l (mm), has the discharge hole, the length is the length corresponding to each discharge hole regardless of the presence of one or more discharge holes, or the length to the outer peripheral surface of the blade-like member when gas flows from an arbitrary position or outer peripheral surface below the blade-like member and the gas is discharged upward on the outer peripheral surface of the blade-like member.
Even if they coexist, the respective discharge gases determine the ratio of the inner hole side/floating height of the above formula by the l (mm) thereof. Whether or not to coexist and how the amount to be used are related to the control of the discharge amount and the form of the gas in the entire nozzle of the tundish, and this can be set according to individual operating conditions (arbitrarily).
Further, if the right side of the expressions 1 and 2 is curved, as shown in fig. 2, substantially all of the gas can be floated within the tundish when the length L is in a region above the approximate line, and the flow rate and floating amount of the gas to the lower part of the inner hole side can be adjusted when the length L is in a region below the approximate line.
Next, the technical basis (derivation basis) of the above-described formulas 1 and 2 and the like will be described.
First, simulation was performed using flow analysis software (fluent) under the following conditions.
The inner diameter of the nozzle on the tundish being
Diameter of the fitting portion at the time of full closure as stopper control
The space is about 12mm and the space is,
the vomit holes are
→ 13b (24 holes), 13a (6 holes)
Bubble diameter of
The casting speed is 0 to 5 t/min.
Further, a water model experiment was performed under the following conditions.
The inner diameter of the nozzle on the tundish being
Diameter of the fitting portion at the time of full closure as stopper control
The space is about 15mm in size,
the vomit holes are
(the diameter of the bubble is about as a result)
)，
The casting speed was 3 t/min.
In addition, the inventors found from the results of practical operations and the like in the experiments so far, that the diameter of the air discharge hole in the water phantom was set to
When the diameter of the bubbles is about
The gas flow rate in the molten steel is further increased to 2 to 3 times that in the molten steel, and the gas discharge hole is also found
The size of the through-holes and the diameter of the bubbles in the alumina-graphite porous body (so-called porous refractory) are substantially the same as each other, and the average gas pore diameter is about 100 to 120 μm.
The length l (mm) described above (each marked position in fig. 2) was obtained as a boundary value that enables substantially all of the gas blown in from the outer periphery (13a) to float up and the result was expressed by an approximation line and an approximation formula of regression analysis by simulation while changing the casting speed, and the following formula 3 was obtained.
LB＝-1.875M2+26.332M-0.3929 … formula 3
In comparison of these simulations to the water model experiments, the aforementioned length l (mm) is approximately consistent.
In other words, when the length l (mm) is larger than the boundary length lb (mm) satisfying the above expression 3, substantially all of the gas can be floated, or when the length l (mm) is smaller than the boundary length lb (mm), the flow rate of the gas downward toward the inner hole side and the floating amount can be adjusted.
In fig. 2, the vertical axis l (mm) is a length from a vertical position of the lower end of the inner hole of the nozzle on the tundish, and therefore, the vertical axis l (mm) is a length including a thickness of the flange portion of the nozzle structure on the tundish. Therefore, the thickness (mm) of the flange is less than lb (mm).
In addition, in normal (most) casting, when the casting speed of the nozzle is about 3(t/min) or more per such tundish, the amount of gas floating is greatly reduced, and in consideration of such a fact, if the length l (mm) is about 60mm or more, substantially all of the gas floats upward.
That is, in normal (many) casting, L ≧ 60mm is required in order to float all the gas (13a) blown from the outer periphery upward, and when L <60mm, the smaller L becomes, the larger the flow rate of the gas toward the lower side of the inner hole becomes (see fig. 3).
Next, a modification of the present embodiment (fig. 1) will be described.
(A) In the present embodiment, the flange 12 is provided on the entire periphery of the upper end portion of the upper nozzle 11 on the tundish, but may be provided on a part of the periphery of the upper end portion of the upper nozzle 11 on the tundish. Even if the position of the collar-like object 12 is a part of the outer periphery of the upper end of the nozzle 11 on the tundish, a large effect of floating gas in the tundish (effect of floating foreign substances in the tundish) can be obtained.
The shape of the flange 12 in plan view is not limited to a circular shape, and may be, for example, an elliptical shape or a polygonal shape.
(B) In the present embodiment, a plurality of (6 in the circumferential direction at equal intervals) air discharge holes 13a are provided in the outer circumferential surface of the upper nozzle 11 of the tundish below the flange 12, but one or a plurality of air discharge holes 13a may be provided in any one or more of the lower surface, the outer circumferential surface, and the upper surface of the flange 12. Thus, when the gas discharge holes 13a are provided in the flange-like material 12, the gas discharge holes 13a of the flange-like material 12 can form holes that penetrate from the end of the gas flow path, which is the space inside the flange-like material 12, or from the lower surface of the flange-like material 12 to the upper surface.
(C) Although the space S through which gas can pass is provided on the lower surface of the collar 12 in the present embodiment, one or more grooves through which gas can pass may be provided on the lower surface of the collar 12.
The groove includes a configuration in which the lower surface of the collar-like member 12 is curved in the circumferential direction, a portion in the circumferential direction is formed into a concave shape, and the concave portion extends in the radial direction. That is, the groove may have a structure as a gas flow path that allows the gas to flow in the outer circumferential direction in a concentrated manner.
Instead of the space, a porous refractory having high gas permeability may be provided at the position of the space S.
(D) In the present embodiment, the flange 12 is joined to the upper tundish nozzle 11 by an adhesive, but may be joined to the upper tundish nozzle 11 by a screw or a snap-fit (bayonet) structure.
The collar 12 may be fitted to the outer periphery of the upper tundish nozzle 11 and may be joined to the tuyere 31 or the refractory layer 32 of the tundish bottom adjacent to the upper tundish nozzle 11. The engagement may be by a screw or snap-in construction or by an adhesive material.
(E) The nozzle structure 10 on a tundish of the present embodiment is used for continuous casting of steel in which the flow rate of molten steel is controlled by the stopper rod 20, but may be used for continuous casting of steel in which the flow rate of molten steel is controlled by a slide nozzle device. That is, the present invention can be applied to a so-called obstacle-free structure in which the flow of molten steel is changed above the nozzle on the tundish.
Examples
Under the following casting conditions and conditions of the nozzle on the tundish, a continuous casting test of steel was performed using a conventional product (comparative example) provided with no collar 12 and the product of the present invention (example) provided with the collar 12 and having the length l (mm) varying within a range of 30 to 60mm, in which the flow rate of molten steel was controlled by a stopper rod, and the thickness of alumina deposited in the nozzle on the tundish and the number of surface defects generated in the product, that is, a coil material were evaluated. Specifically, the thickness of alumina deposited in the nozzle on the tundish of the conventional product was defined as 1.0, and the thickness of alumina deposited in the nozzle on the tundish of the present invention was indexed. The smaller the alumina adhesion thickness index in the nozzle, the smaller the alumina adhesion thickness in the nozzle on the tundish. The number of surface defects of the coil in the conventional product was set to 1.0, and the number of surface defects of the coil in the product of the present invention was indexed. The smaller the coil surface defect generation index is, the smaller the generation amount of surface defects of the coil is, that is, the better the quality of cast pieces is.
(casting conditions)
Steel grade: ordinary aluminum killed steel
Casting size: 250mm (thickness) x 1250mm (width)
Casting speed (throughput of molten steel): about 3(t/min)
(nozzle conditions on tundish)
Inner pore diameter: 80mm
Diameter × number of the vomit holes: 0.3 (mm). times.13 b (24 wells), 13a (6 wells)
Gas (Ar) discharge amount: 10(L/min)
Gas (Ar) discharge flow rate: 1.56(m/min)
Table 1 shows the results of the continuous casting test. In addition, since the casting speed (the throughput of molten steel) in this continuous casting test was about 3(t/min), the boundary length LB in the above equation 3 was about 60 mm.
The amount of floating of bubbles (ratio) is an estimated value (example) obtained by visual observation, water model experiment, or the like, in an index in which the total amount is 100, 100 means substantially all floating, and 0 means all inflow to the inner hole side.
(Table 1)
As shown in table 1, in the inventive product (example 3) having a boundary length LB (about 60mm) or more of l (mm), the thickness of alumina deposited in the nozzle on the tundish was smaller and the number of surface defects of the coil was also smaller than in the conventional product (comparative example 1).
In addition, the ratio of the amount of bubbles floating up to the amount of the inner hole side can be adjusted by adjusting L (mm) of the product of the present invention (examples 1 and 2) having L (mm) smaller than the boundary length LB (about 60mm), which indicates that the quality of the cast slab can also be adjusted.
Claims (12)
1. A nozzle structure on a tundish is characterized in that,
the outer periphery of the upper end part of the nozzle on the sprue plate is provided with a jaw-shaped object larger than the outer shape of the upper end part of the nozzle on the sprue plate, and one or more air discharge holes are formed on any one or more surfaces of the lower surface, the outer periphery surface, the upper surface and the outer periphery surface of the nozzle on the sprue plate below the jaw-shaped object.
2. The nozzle-on-tundish structure of claim 1,
the gas discharge hole of the flange-like material is a hole penetrating the upper surface from the end of the gas flow path, which is the space inside the flange-like material, or the lower surface of the flange-like material.
3. The structure of any one of claims 1 and 2, wherein the lower surface of the collar has one or more grooves through which gas can pass.
4. The nozzle-on-tundish structure according to claim 1 or 2, wherein a space through which gas can pass is provided in a part or the whole of the lower surface of the flange in a state in which the nozzle-on-tundish structure is mounted on the tundish.
5. The nozzle-on-tundish structure of any one of claims 1 to 4,
the nozzle structure on a tundish is used for continuous casting of steel, wherein the flow rate of molten steel is controlled by a stopper rod,
a length L from a vertical position of an inner hole surface of a lower end of a nozzle on the tundish to an upper discharge hole or an outer peripheral surface of the flange: mm satisfies the following formula 1,
L≧-1.875M2+26.332M-0.3929 … formula 1
Here, M: and the casting speed is t/min.
6. The nozzle-on-tundish structure of any one of claims 1 to 4,
the nozzle structure on a tundish is used for continuous casting of steel, wherein the flow rate of molten steel is controlled by a stopper rod,
a length L from a vertical position of an inner hole surface of a lower end of a nozzle on the tundish to an upper discharge hole or an outer peripheral surface of the flange: mm satisfies the following formula 2,
L<-1.875M2+26.332M-0.3929 … formula 2
Here, M: and the casting speed is t/min.
7. The nozzle-on-tundish structure of any one of claims 1 to 5,
a length L from a vertical position of an inner hole surface of a lower end of a nozzle on the tundish to an upper discharge hole or an outer peripheral surface of the flange: the mm is more than 60 mm.
8. A nozzle on tundish nozzle structure according to any one of claims 1 to 7, wherein the collar engages the nozzle on the tundish.
9. The nozzle-on-tundish structure of claim 8, wherein the collar and nozzle-on-tundish are joined by a screw or snap-fit arrangement or an adhesive material.
10. A nozzle on tundish structure according to any one of claims 1 to 7, wherein the collar engages the periphery of the nozzle on the tundish and engages with a tuyere or a refractory layer at the bottom of the tundish adjacent to the nozzle on the tundish.
11. The nozzle-on-tundish structure of claim 10, wherein the collar and the tuyere or the refractory layer at the bottom of the tundish are joined by a screw or a snap-fit arrangement or an adhesive material.
12. A continuous casting method using the tundish upper nozzle structure according to any one of claims 1 to 4,
the nozzle structure on a tundish is used for continuous casting of steel, the flow rate of molten steel is controlled by a stopper rod,
a length L from a vertical position of an inner hole surface of a lower end of a nozzle on the tundish to an upper orifice or an outer peripheral surface of the flange is set to: mm is the boundary length LB satisfying the following formula 3: mm or more so as to float substantially all of the gas, or less than the boundary length LB: mm to adjust the flow rate and the floating amount of the gas facing the lower part of the inner hole side,
LB＝-1.875M2+26.332M-0.3929 … formula 3
Here, M: and the casting speed is t/min.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2019-175256 | 2019-09-26 | ||
| JP2019175256A JP2021049564A (en) | 2019-09-26 | 2019-09-26 | Tundish upper nozzle structure and method of continuous casting |
| PCT/JP2020/035165 WO2021060122A1 (en) | 2019-09-26 | 2020-09-17 | Tundish nozzle structure and continuous casting method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114040823A true CN114040823A (en) | 2022-02-11 |
Family
ID=75155231
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202080046023.XA Pending CN114040823A (en) | 2019-09-26 | 2020-09-17 | Nozzle structure on tundish and continuous casting method |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US20220324017A1 (en) |
| EP (1) | EP4035795A4 (en) |
| JP (1) | JP2021049564A (en) |
| CN (1) | CN114040823A (en) |
| BR (1) | BR112022001629A2 (en) |
| TW (1) | TWI770616B (en) |
| WO (1) | WO2021060122A1 (en) |
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| EP0059805A1 (en) * | 1981-03-11 | 1982-09-15 | Junichi Ato | Porous nozzle for molten metal vessel |
| US4360190A (en) * | 1981-03-16 | 1982-11-23 | Junichi Ato | Porous nozzle for molten metal vessel |
| US4468012A (en) * | 1981-11-13 | 1984-08-28 | Daussan Et Compagnie | Device for the removal of inclusions contained in molten metals |
| JPS60115353A (en) * | 1983-11-18 | 1985-06-21 | ユーエス エス エンジニアーズ アンド コンサルタンツ インコーポレーテツド | Method and device for removing eddy in bottom casting vessel |
| EP0187924A1 (en) * | 1984-11-26 | 1986-07-23 | Cometus AG | Process and ladle for gas purging molten metals |
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| JP2017064778A (en) * | 2015-10-02 | 2017-04-06 | 新日鐵住金株式会社 | Upper nozzle for continuous casting |
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| JP4139366B2 (en) * | 2004-08-26 | 2008-08-27 | 黒崎播磨株式会社 | Molten metal discharge nozzle with function of blowing gas |
| AU2012343466B2 (en) * | 2011-12-01 | 2015-02-12 | Krosakiharima Corporation | Refractory and nozzle for casting |
| JP2016182612A (en) | 2015-03-25 | 2016-10-20 | 株式会社神戸製鋼所 | Continuous casting method blowing inert gas from upper porous refractory and lower porous refractory |
| JP6663230B2 (en) * | 2016-01-25 | 2020-03-11 | 黒崎播磨株式会社 | Nozzle structure |
| JP6649795B2 (en) * | 2016-02-19 | 2020-02-19 | 黒崎播磨株式会社 | How to replace the immersion nozzle |
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- 2019-09-26 JP JP2019175256A patent/JP2021049564A/en active Pending
-
2020
- 2020-09-17 BR BR112022001629A patent/BR112022001629A2/en unknown
- 2020-09-17 EP EP20868567.7A patent/EP4035795A4/en not_active Withdrawn
- 2020-09-17 WO PCT/JP2020/035165 patent/WO2021060122A1/en unknown
- 2020-09-17 CN CN202080046023.XA patent/CN114040823A/en active Pending
- 2020-09-17 US US17/639,848 patent/US20220324017A1/en not_active Abandoned
- 2020-09-24 TW TW109133031A patent/TWI770616B/en active
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0059805A1 (en) * | 1981-03-11 | 1982-09-15 | Junichi Ato | Porous nozzle for molten metal vessel |
| US4360190A (en) * | 1981-03-16 | 1982-11-23 | Junichi Ato | Porous nozzle for molten metal vessel |
| US4468012A (en) * | 1981-11-13 | 1984-08-28 | Daussan Et Compagnie | Device for the removal of inclusions contained in molten metals |
| JPS60115353A (en) * | 1983-11-18 | 1985-06-21 | ユーエス エス エンジニアーズ アンド コンサルタンツ インコーポレーテツド | Method and device for removing eddy in bottom casting vessel |
| EP0187924A1 (en) * | 1984-11-26 | 1986-07-23 | Cometus AG | Process and ladle for gas purging molten metals |
| JPH04100662A (en) * | 1990-08-20 | 1992-04-02 | Kawasaki Refract Co Ltd | Method for flowing out molten metal in molten metal vessel |
| GB9312074D0 (en) * | 1992-06-18 | 1993-07-28 | Foseco Int | Purifying molten metal |
| JPH06297118A (en) * | 1993-04-12 | 1994-10-25 | Nippon Steel Corp | Stopper receiving nozzle at bottom part of tundish |
| JPH09314294A (en) * | 1996-05-28 | 1997-12-09 | Akechi Ceramics Kk | Immersion nozzle for continuous casting |
| JPH1034299A (en) * | 1996-07-26 | 1998-02-10 | Nippon Steel Corp | Pouring device |
| JP2003220450A (en) * | 2002-01-28 | 2003-08-05 | Nisshin Steel Co Ltd | Tundish nozzle structure |
| JP2017064778A (en) * | 2015-10-02 | 2017-04-06 | 新日鐵住金株式会社 | Upper nozzle for continuous casting |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2021060122A1 (en) | 2021-04-01 |
| EP4035795A4 (en) | 2023-02-08 |
| JP2021049564A (en) | 2021-04-01 |
| TW202128310A (en) | 2021-08-01 |
| BR112022001629A2 (en) | 2022-04-19 |
| US20220324017A1 (en) | 2022-10-13 |
| TWI770616B (en) | 2022-07-11 |
| EP4035795A1 (en) | 2022-08-03 |
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