WO2023228864A1 - Gas blowing-up nozzle and continuous casting method - Google Patents

Gas blowing-up nozzle and continuous casting method Download PDF

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Publication number
WO2023228864A1
WO2023228864A1 PCT/JP2023/018626 JP2023018626W WO2023228864A1 WO 2023228864 A1 WO2023228864 A1 WO 2023228864A1 JP 2023018626 W JP2023018626 W JP 2023018626W WO 2023228864 A1 WO2023228864 A1 WO 2023228864A1
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Prior art keywords
gas
metal case
nozzle
gas blowing
blowing
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PCT/JP2023/018626
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French (fr)
Japanese (ja)
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真吾 岡本
喜則 山迫
悟 清水
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Ｊｆｅスチール株式会社
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Publication of WO2023228864A1 publication Critical patent/WO2023228864A1/en

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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
    • 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
    • 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

Definitions

  • the present invention relates to a gas blowing nozzle installed at the bottom of a tundish and used in hot conditions, and a continuous casting method using the same.
  • inert gas is blown through the nozzle to float and separate the inclusions, thereby preventing the inclusions from adhering to the nozzle and clogging the nozzle.
  • Gas blowing using a continuous casting nozzle is generally performed using an upper nozzle installed in a tundish, a sliding plate, and an immersion nozzle connected to the lower part thereof.
  • vent holes penetrating porous gas-permeable materials or refractories may be used.
  • a porous gas-permeable material when used, it is often composed of a fire-resistant material 1 that is a combination of a gas-impermeable material 1A and a gas-permeable material 1B.
  • the outer periphery of the upper gas blowing nozzle 100 is kept airtight by the metal case 2.
  • the inert gas is introduced through an inert gas introduction pipe 6 installed at the lower side of the upper gas blowing nozzle 100.
  • a part of the inert gas is introduced into the upper part of the gas-permeable material 1B through the gas flow path provided between the refractory outer periphery of the gas-impermeable material 1A and the metal case 2, that is, the gas pool 5. be done. Then, it is blown into the molten steel flow flowing down through the through hole 11 of the gas blowing upper nozzle 100. Further, the remainder of the inert gas is blown into the molten steel flow flowing down through the through hole 11 of the gas blowing upper nozzle 100 through the lower gas permeable material 1B.
  • the sealing performance between the metal case 2 provided on the outer periphery and the fireproof material 1 has been a problem for some time.
  • the inert gas will leak through the outer periphery of the refractory material 1 and leak into the molten steel from the tundish bottom. Therefore, the amount of inert gas to be blown into the molten steel passing through the through hole 11 of the gas blowing upper nozzle 100 is not sufficiently secured. Slabs cast in such conditions end up being out of specification.
  • FIG. 4(b) is an enlarged schematic diagram of a portion B shown in two-dot chain line in FIG. 4(a), that is, the vicinity of the upper end of the gas blowing upper nozzle 100.
  • FIG. 4(b) shows the upper end of the metal case 2 being opened due to thermal deformation (indicated by an arrow).
  • the metal case 2 of the upper nozzle becomes hot due to heat transfer from the molten steel, causing thermal expansion.
  • the upper nozzle set mortar 10 is pushed away, and the upper end of the metal case 2 opens away from the refractory material 1 as shown by the arrow.
  • the metal case 2 deforms in this way, a gap is created between the seal mortar part 4 and the metal case 2.
  • the inert gas leak phenomenon is caused by the formation of a gap between the metal case 2 and the refractory material 1 as described above, which reduces the sealing performance of the seal mortar part 4 and forms a leak path. There is. Note that the occurrence of gas leak can be ascertained by detecting a change in the gas blowing pressure (back pressure). When a gas leak occurs, back pressure decreases. For this reason, when blowing gas during continuous casting, we have built a system in which the back pressure of the blown gas is monitored, and when a drop in back pressure occurs, it is determined that there is an abnormality.
  • back pressure gas blowing pressure
  • Patent Documents 1 and 2 use thermally expandable mortar that fills the gap created between the metal case and the gas-permeable material due to thermal expansion of the metal case.
  • the coefficient of thermal expansion is generally large for metal cases and small for refractories.
  • the metal case expands more than the nozzle refractory outer periphery, creating a gap between the nozzle refractory outer periphery and the metal case, from which gas leaks.
  • expandable mortar is used to suppress gas leaks.
  • Patent Document 3 thermal expansion of the metal case is suppressed by improving the binding force.
  • Patent Document 4 by disposing a flexible fireproof sealing material on the outer peripheral portion of the metal case, the fireproof sealing material restrains the metal case from deforming due to thermal expansion, thereby suppressing thermal deformation.
  • the restraining force of the metal case is increased by attaching spiral fins to the outer peripheral portion of the metal case.
  • Patent Documents 1 and 2 even if the thermal expansion coefficient of the mortar between the metal case and the gas-permeable material is improved, there is a limit to the amount of thermal expansion of the mortar. If the metal case expands beyond the amount of expansion of the mortar, there is a problem that gas leakage between the metal case and the refractory material cannot be completely prevented. Further, as in Patent Document 2, when a foamable material is used to improve the thermal expansion coefficient of mortar, the density of the mortar itself decreases, resulting in a problem of decreased sealing performance.
  • the method of physically suppressing thermal expansion of the metal case by improving the binding force of the metal case also has the following problems.
  • the method of wrapping a flexible fireproof seal around the outer periphery of a metal case as in Patent Document 3 is expected to be effective in reducing thermal deformation of the metal case in the part where the fireproof sealing material is wrapped, but it is not effective in reducing thermal deformation of the metal case in other parts. cannot suppress thermal expansion.
  • the fireproof seal is wrapped around the entire structure, the adhesion between the upper nozzle and the surrounding mass bricks will decrease, and the upper nozzle will shift vertically, which may increase the risk of steel leakage. Therefore, it cannot be said that this method is sufficient as a gas leak prevention method.
  • a method of installing fins on the outer periphery of the metal case as in Patent Document 4 can be expected to have the effect of reducing thermal deformation of the entire metal case.
  • the upper nozzle into the surrounding mass bricks if the dimensions are such that the fins come into contact with the mass bricks, there is a risk of damaging the mass bricks themselves. Therefore, there is a problem that the operation of inserting the upper nozzle itself becomes difficult.
  • the outer diameter of the fin is designed to be smaller than the inner diameter of the mass brick, the effect of improving strength will be reduced, and there is a problem that thermal expansion of the metal case cannot be completely suppressed.
  • the present invention aims to solve the above-mentioned conventional problems and provide a technology that can prevent gas leaks when blowing inert gas from a gas blowing upper nozzle during continuous casting of molten steel.
  • gas leak refers to inert gas flowing out from between the metal case provided on the outer periphery of the gas blowing upper nozzle and the refractory material to a portion other than the gas permeable material.
  • the gas blowing nozzle according to the present invention which advantageously solves the above problems, includes a fireproof material (1) including a gas permeable material (1B), and a metal case (2) surrounding the outer periphery of the fireproof material (1). , has an upper end metal case (3) extending inward from the upper end of the metal case (2), and has a sealing mortar part (4) between the refractory material (1) and the metal case (2). ) The upper end is covered by the upper end metal case (3).
  • the gas blowing nozzle according to the present invention is (a) The extension length of the upper end metal case (3) is greater than or equal to the joint thickness between the metal case (2) and the mass brick (8); (b) The extended tip of the upper end metal case (3) is within a range covered by being sandwiched between the flat top end of the refractory material (1) and the upper nozzle upper refractory material (9). , etc. may be a more preferable solution.
  • a continuous casting method which advantageously solves the above problems, includes installing any of the above gas blowing upper nozzles at the bottom of the tundish, and blowing an inert gas into the gas permeable material. It is characterized by injecting molten steel into the mold from the tundish through the tundish.
  • the gas blowing upper nozzle is formed of a fireproof material including a gas permeable material and a metal case having an upper end metal case. Even if a gap occurs at the joint between the fireproof material and the metal case due to thermal deformation of the metal case, the upper metal case, which is placed to cover the joint at the top of the upper nozzle, physically prevents the gas leakage path. It plays the role of blocking. By doing so, gas leaks can be prevented.
  • molten steel is injected into the mold from the tundish through the above-mentioned gas blowing nozzle, so continuous casting can be performed without gas leakage, and the quality of the slab can be maintained in good condition. .
  • FIG. 1 is a longitudinal cross-sectional view of a gas blowing upper nozzle according to an embodiment of the present invention.
  • (a) is a schematic cross-sectional view of the gas blowing upper nozzle of the above embodiment installed in a tundish, and (b) is a partially enlarged cross-sectional view of part A thereof. It is a conceptual sectional view showing the state where the metal case of the gas blowing upper nozzle of the above-mentioned embodiment thermally expanded.
  • (a) is a schematic cross-sectional view of a conventional gas blowing nozzle installed in a tundish, and (b) is a partially enlarged cross-sectional view of part B thereof, which is a conceptual cross-sectional view showing a state in which the metal case is thermally expanded. It is. It is a graph evaluating the gas leak situation when continuous casting is performed using the gas blowing nozzle of the above embodiment in comparison with a conventional example.
  • FIG. 1 is a diagram showing a vertical cross section of a gas blowing upper nozzle according to an embodiment of the present invention.
  • the refractory material 1 inside the gas blowing upper nozzle 100 has a through hole 11 through which molten steel flows along the rotation axis (axis of symmetry) CL, and has a hollow, thick-walled rotating body shape.
  • the through hole 11 widens toward the top in a morning glory shape.
  • the fireproof material 1 has a flat part at the top (upper end). In the example shown in FIG. 1, it is made of a combination of a gas non-permeable material 1A and a gas permeable material 1B.
  • the gas permeable material 1B can be placed at any position.
  • Gas can be injected into the molten steel passing through the through hole 11 from the position where the gas permeable material 1B is arranged.
  • the gas-impermeable material 1A can also be placed at any position. If you want to blow gas separately from the upper and lower parts as shown in Figure 1, you can separate the blowing by placing the gas non-permeable material 1A at the boundary of the gas permeable material 1B. become. Note that, if there is no particular need to separate the gas, there is no problem in a structure in which all of the refractory material 1 is made of the gas-permeable material 1B.
  • the inert gas supply route to the gas permeable material 1B is configured as follows. First, an inert gas is introduced into the gas blow-up nozzle 100 through the inert gas introduction pipe 6 . Thereafter, the gas passes through a gas pool 5 provided between the refractory material 1 and a substantially cylindrical metal case 2 that covers the outer periphery of the refractory material 1, and reaches the gas permeable material 1B.
  • the gas pool 5 is provided between the refractory material 1 and the metal case 2, but the gas pool 5 can also be configured by providing a slit in the refractory material 1.
  • a structure in which a gas pool 5 is provided between the fireproof material 1 and the metal case 2 as shown in FIG. 1 can enjoy the effect more markedly.
  • a gas leak The leakage of inert gas to the outside of the gas blowing nozzle 100 from a portion other than the gas permeable material 1B is called a gas leak. If a gas leak occurs, a sufficient amount of inert gas will not be supplied to the molten steel in the hollow part of the gas blowing nozzle 100. Therefore, a sufficient effect on improving the cleanliness of molten steel cannot be obtained. As a result, quality problems may occur in the cast slab.
  • a seal mortar section 4 is disposed between the refractory material 1 and the metal case 2. The seal mortar part 4 fills the gap between the refractory material 1 and the metal case 2 except for the gas pool 5. The seal mortar portion 4 plays a role in preventing inert gas from leaking out of the gas blow-up nozzle 100.
  • FIG. 2(a) A schematic diagram of the gas blowing upper nozzle 100 of this embodiment set in a tundish is shown in FIG. 2(a).
  • the gas blowing upper nozzle 100 is surrounded by a tundish iron skin 7, a mass brick 8, and a refractory material 9 above the upper nozzle.
  • the upper gas blowing nozzle 100 is restrained by surrounding materials.
  • An upper nozzle set mortar 10 is arranged at the joint between the mass brick 8 and the metal case 2, so that no gap is left.
  • the binding force to the gas blowing upper nozzle 100 is guaranteed by the adhesive force between the mass brick 8, the upper nozzle set mortar 10, and the metal case 2.
  • FIG. 2(b) shows an enlarged view of the upper end of the gas blowing upper nozzle 100, which is surrounded by the chain double-dashed line section A in FIG. 2(a).
  • This embodiment has an upper end metal case 3 extending inward from the upper end of the metal case 2 .
  • the upper end of the seal mortar part 4 (joint part) between the refractory material 1 and the metal case 2 is covered by the upper end metal case 3.
  • the upper end outer periphery of the metal case 2 and the upper end metal case 3 may be connected, for example, by welding or caulking, or the metal case 2 and the upper end metal case 3 may be integrally formed by drawing or the like.
  • the upper end metal case 3 has an annular shape along the flat part of the top end of the refractory material 1.
  • An upper end metal case 3 is arranged at the upper end of the upper gas blowing nozzle 100, and the upper end metal case 3 and the metal case 2 on the outer periphery of the upper nozzle are connected without a gap.
  • the upper end metal case 3 and the seal mortar part 4 block the gas leak path that occurs at the joint between the refractory material 1 and the metal case 2, and the gas leak does not occur.
  • the route can be physically blocked.
  • the limit length in which the metal case 2 opens due to thermal deformation depends on the joint thickness between the metal case 2 and the mass bricks 8. Therefore, in order to have the effect of preventing gas leakage even if the metal case 2 undergoes maximum thermal deformation, the extension length of the upper end metal case 3 should be greater than the joint thickness between the metal case 2 and the mass brick 8. is preferred. Furthermore, if the upper end metal case 3 comes into direct contact with molten steel, it will melt and will no longer be able to maintain its shape.
  • the extension length of the upper end metal case 3 can be kept within the range covered by being sandwiched between the flat top end of the refractory material 1 of the gas blowing upper nozzle and the upper nozzle upper refractory material 9 at most. preferable.
  • the extended length of the upper end metal case 3 is defined as the length in the radial direction in a cylindrical coordinate system having the rotation axis CL as the central axis.
  • the refractory material 1 is, for example, a high alumina material
  • the metal case 2 and the upper end metal case 3 are made of metal, such as carbon steel, alloy steel, stainless steel, cast steel, cast iron, titanium, and titanium alloy. is preferably used.
  • the seal mortar part 4 and the upper nozzle set mortar 10 can be made of, for example, high alumina water-mixed mortar adjusted to an appropriate consistency.
  • the thickness of the joint between the metal case (2) and the mass brick (8) is about 1 to 5 mm.
  • the range sandwiched between the flat top end of the refractory material 1 of the gas blowing upper nozzle 100 and the upper nozzle upper refractory material 9 is about 5 to 20 mm in radial length from the rotation axis CL.
  • the gas blowing upper nozzle 100 of the above embodiment is installed at the bottom of the tundish as shown in FIG. 2. Then, the inert gas introduced from the inert gas introduction pipe 6 is caused to flow into the molten steel flowing down through the through hole 11 through the gas permeable material 1B. The molten steel in the tundish is injected into the mold via the gas blowing nozzle 100 and, if necessary, a sliding nozzle or a submerged nozzle.
  • the seal mortar portion 4 which is the joint between the fireproof material 1 and the metal case 2, is not exposed to the outside despite thermal deformation of the metal case 2. It is necessary to cover it like this. With such a configuration, gas leaks can be prevented.
  • FIGS. 1 and 2 and the conventional gas blowing upper nozzle shown in FIG. 4 are installed at the bottom of the tundish and continuous casting is performed, and whether there is any gas leakage due to the back pressure of the inert gas blown into the gas blowing upper nozzle.
  • the results of the evaluation are shown in Figure 5. Whether or not a gas leak has occurred can be determined by monitoring the back pressure of the inert gas flowing through the upper gas blowing nozzle. In other words, when the inert gas is normally blown into the molten steel from the gas-permeable material 1B, the back pressure of the inert gas is equal to the resistance pressure that is the sum of the static pressure of the molten steel and the ventilation resistance of the gas-permeable material 1B.
  • the resistance pressure appears as back pressure. However, when a gas leak occurs, the back pressure decreases because at least the gas permeable material 1B no longer generates ventilation resistance. Therefore, whether or not a gas leak has occurred is determined based on the presence or absence of a decrease in back pressure, and the effects of the present embodiment and the conventional gas blow-up nozzle were verified.
  • the back pressure threshold used for determination depends on the casting equipment and operating rate, so it needs to be optimized for each individual continuous casting machine.
  • a reduction in back pressure of approximately 30% compared to the normal back pressure was referred to as a reduction in back pressure.
  • the incidence of back pressure drop was 0.018.
  • continuous casting can be performed while blowing the inert gas into the molten steel without gas leakage, so the quality of the slab can be maintained at a good level, which is industrially useful.

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Abstract

Provided is a gas blowing-up nozzle that can prevent gas leakage and a continuous casting method using the same. This gas blowing-up nozzle is provided with a fire resistant material (1) including a gas permeable material (1B) and a metal case (2) that surrounds the outer periphery of the fire resistant material (1), the nozzle has an upper end metal case (3) that extends inward from the upper end portion of the metal case (2), and an upper end of a sealing mortar portion (4) between the fire resistant material (1) and the metal case (2) is covered by the upper end metal case (3). This continuous casting method disposes said gas blowing-up nozzle in a bottom portion of a tundish and injecting a molten steel into a mold from the tundish through the gas blowing-up nozzle while blowing an inert gas into the gas permeable material.

Description

ガス吹き上ノズルおよび連続鋳造方法Gas blowing nozzle and continuous casting method
　本発明は、タンディッシュの底部に設けられ、熱間で使用されるガス吹き上ノズルおよびそれを用いた連続鋳造方法に関するものである。 The present invention relates to a gas blowing nozzle installed at the bottom of a tundish and used in hot conditions, and a continuous casting method using the same.
　従来、溶鋼の連続鋳造においては、使用するガス吹き上ノズルの内壁に溶鋼中のアルミナ（Ａｌ２Ｏ３）などの介在物が付着して堆積し、しばしばノズル閉塞が発生している。ノズル閉塞が発生すると、溶鋼の注入途中で閉塞物が剥がれて鋳片内に混入したり、閉塞によってノズル内の溶鋼に偏流が発生したりして、鋳片の品質トラブルの原因になる。 Conventionally, in continuous casting of molten steel, inclusions such as alumina (Al 2 O 3 ) in the molten steel adhere to and accumulate on the inner wall of the gas blowing nozzle used, often causing nozzle blockage. If a nozzle blockage occurs, the blockage may come off during the injection of molten steel and get mixed into the slab, or the blockage may cause a drift in the molten steel in the nozzle, causing problems with the quality of the slab.
　ノズル閉塞防止の一対策として、ノズルから不活性ガスを吹き込んで、介在物の浮上分離を図り、介在物のノズルへの付着や閉塞の防止を図ることが行われる。連続鋳造用ノズルでのガス吹きは、タンディッシュに設置された上ノズル、スライディングプレートおよびその下部に接続された浸漬ノズルなどで行われるのが一般的である。 As a measure to prevent nozzle clogging, inert gas is blown through the nozzle to float and separate the inclusions, thereby preventing the inclusions from adhering to the nozzle and clogging the nozzle. Gas blowing using a continuous casting nozzle is generally performed using an upper nozzle installed in a tundish, a sliding plate, and an immersion nozzle connected to the lower part thereof.
　ガス吹き上ノズルでのガス吹きには、ポーラスなガス通気性材質や耐火物を貫通した通気孔を用いる場合がある。図４（ａ）に示すように、ポーラスなガス通気性材質を用いる場合はガス非通気性材質１Ａとガス通気性材質１Ｂとを組み合わせた耐火材質１で構成されることが多い。そして、ガス吹き上ノズル１００の外周は、メタルケース２によって気密に保たれている。不活性ガスはガス吹き上ノズル１００の側方下部に設置した不活性ガス導入管６を介して導入される。その不活性ガスの一部はガス非通気性材質１Ａの耐火物外周とメタルケース２との間に設けられたガス流路、つまり、ガスプール５を通じて、上部のガス通気性材質１Ｂ部分へ導入される。そして、ガス吹き上ノズル１００の貫通孔１１を流下する溶鋼流内に吹き込まれる。また、不活性ガスの残部は、下部のガス通気性材質１Ｂを通じてガス吹き上ノズル１００の貫通孔１１を流下する溶鋼流内に吹き込まれる。この際、ガス吹き上ノズル１００の耐火材質１の外周とメタルケース２との間からガスがリークしてガス吹き上ノズル内を流下する溶鋼流内に所定の量の不活性ガスが吹き込まれないことが懸念される。そこで、シールモルタル部４などによってガス非通気性材質１Ａの耐火物外周とメタルケース２との間が接着され、ガスリークを抑制している。 For blowing gas with the upper gas blowing nozzle, vent holes penetrating porous gas-permeable materials or refractories may be used. As shown in FIG. 4(a), when a porous gas-permeable material is used, it is often composed of a fire-resistant material 1 that is a combination of a gas-impermeable material 1A and a gas-permeable material 1B. The outer periphery of the upper gas blowing nozzle 100 is kept airtight by the metal case 2. The inert gas is introduced through an inert gas introduction pipe 6 installed at the lower side of the upper gas blowing nozzle 100. A part of the inert gas is introduced into the upper part of the gas-permeable material 1B through the gas flow path provided between the refractory outer periphery of the gas-impermeable material 1A and the metal case 2, that is, the gas pool 5. be done. Then, it is blown into the molten steel flow flowing down through the through hole 11 of the gas blowing upper nozzle 100. Further, the remainder of the inert gas is blown into the molten steel flow flowing down through the through hole 11 of the gas blowing upper nozzle 100 through the lower gas permeable material 1B. At this time, gas leaks from between the outer periphery of the refractory material 1 of the gas blowing upper nozzle 100 and the metal case 2, and a predetermined amount of inert gas is not blown into the molten steel flow flowing down inside the gas blowing upper nozzle. This is a concern. Therefore, the refractory outer periphery of the gas-impermeable material 1A and the metal case 2 are bonded together by a seal mortar portion 4 or the like to suppress gas leakage.
　一方、外周に設けたメタルケース２と耐火材質１とのシール性が従来から問題となっている。たとえば、仮にメタルケース２と耐火材質１との間のシールが阻害されると、不活性ガスは耐火材質１の外周を通じてリークし、タンディッシュ敷部から溶鋼内に洩れ出す。そのため、ガス吹き上ノズル１００の貫通孔１１を通過する溶鋼中に吹き込もうとする不活性ガス量が、十分には確保されないことになる。そのような状態で鋳込まれた鋳片は、規格外となってしまう。 On the other hand, the sealing performance between the metal case 2 provided on the outer periphery and the fireproof material 1 has been a problem for some time. For example, if the seal between the metal case 2 and the refractory material 1 is disturbed, the inert gas will leak through the outer periphery of the refractory material 1 and leak into the molten steel from the tundish bottom. Therefore, the amount of inert gas to be blown into the molten steel passing through the through hole 11 of the gas blowing upper nozzle 100 is not sufficiently secured. Slabs cast in such conditions end up being out of specification.
　図４（ｂ）は図４（ａ）の二点鎖線部Ｂ、つまり、ガス吹き上ノズル１００の上端部付近を拡大した模式図である。図４（ｂ）では、熱変形（矢印で示す）により、メタルケース２の上端が開いた様子を示す。連続鋳造を繰り返していくと、溶鋼からの伝熱により上ノズルのメタルケース２が高温となり、熱膨張する。その際、上ノズルセットモルタル１０を押しのけ、矢印で示すように耐火材質１から遠ざかるようにメタルケース２上端が開いていく。このようにメタルケース２が変形すると、シールモルタル部４とメタルケース２の間に隙間が生じてしまう。この隙間を通じてガスリークが発生しやすくなる。不活性ガスのリーク現象は、上記のようにメタルケース２と耐火材質１との間に隙間が生じ、シールモルタル部４によるシール性が低下してリーク経路が形成されることが原因となっている。なお、ガスリークの発生は、ガス吹きの圧力（背圧）の変化を検出することにより把握できる。ガスリークが起こると背圧が低下する。このため、連続鋳造中にガス吹きを行う場合には、吹込みガスの背圧をモニタリングし、背圧低下が起こった際には、異常と判定する仕組みを構築している。 FIG. 4(b) is an enlarged schematic diagram of a portion B shown in two-dot chain line in FIG. 4(a), that is, the vicinity of the upper end of the gas blowing upper nozzle 100. FIG. 4(b) shows the upper end of the metal case 2 being opened due to thermal deformation (indicated by an arrow). As continuous casting is repeated, the metal case 2 of the upper nozzle becomes hot due to heat transfer from the molten steel, causing thermal expansion. At this time, the upper nozzle set mortar 10 is pushed away, and the upper end of the metal case 2 opens away from the refractory material 1 as shown by the arrow. When the metal case 2 deforms in this way, a gap is created between the seal mortar part 4 and the metal case 2. Gas leaks are likely to occur through this gap. The inert gas leak phenomenon is caused by the formation of a gap between the metal case 2 and the refractory material 1 as described above, which reduces the sealing performance of the seal mortar part 4 and forms a leak path. There is. Note that the occurrence of gas leak can be ascertained by detecting a change in the gas blowing pressure (back pressure). When a gas leak occurs, back pressure decreases. For this reason, when blowing gas during continuous casting, we have built a system in which the back pressure of the blown gas is monitored, and when a drop in back pressure occurs, it is determined that there is an abnormality.
　上述したようなガスリークを抑制するために、従来から様々な改善がなされてきた。たとえば、特許文献１や２に開示の技術では、メタルケースの熱膨張によってメタルケースとガス通気性材質との間に生じる隙間を埋めるような熱膨張性のモルタルを使用している。これらの特許文献によれば、熱膨張係数は、一般的にメタルケースが大きく、耐火物が小さい。ノズル使用中の加熱によってノズル耐火物外周に比べてメタルケースの膨張が大きくなり、ノズル耐火物外周とメタルケース間の隙間ができ、そこからガスリークする。このための対策として、膨張性のモルタルを使用し、ガスリークを抑制するものである。 Various improvements have been made in the past in order to suppress gas leaks as described above. For example, the techniques disclosed in Patent Documents 1 and 2 use thermally expandable mortar that fills the gap created between the metal case and the gas-permeable material due to thermal expansion of the metal case. According to these patent documents, the coefficient of thermal expansion is generally large for metal cases and small for refractories. When the nozzle is heated during use, the metal case expands more than the nozzle refractory outer periphery, creating a gap between the nozzle refractory outer periphery and the metal case, from which gas leaks. As a countermeasure for this, expandable mortar is used to suppress gas leaks.
　さらに、特許文献３や４に開示の技術では、メタルケースの熱膨張を、拘束力を向上させることで抑えている。特許文献３によれば、メタルケース外周部に可撓性の耐火シール材を配置することにより、メタルケースが熱膨張により変形することを耐火シール材によって拘束し、熱変形を抑止している。また、特許文献４では、メタルケース外周部に螺旋状のフィンを取り付けることでメタルケースの拘束力を高めている。 Furthermore, in the techniques disclosed in Patent Documents 3 and 4, thermal expansion of the metal case is suppressed by improving the binding force. According to Patent Document 3, by disposing a flexible fireproof sealing material on the outer peripheral portion of the metal case, the fireproof sealing material restrains the metal case from deforming due to thermal expansion, thereby suppressing thermal deformation. Further, in Patent Document 4, the restraining force of the metal case is increased by attaching spiral fins to the outer peripheral portion of the metal case.
特開２０１１－２５６０７９号公報Japanese Patent Application Publication No. 2011-256079 特開２００６－１７５４８２号公報Japanese Patent Application Publication No. 2006-175482 特開２０１６－３６８１１号公報Japanese Patent Application Publication No. 2016-36811 特開２０１７－９４３８６号公報JP2017-94386A
　しかしながら、上記従来技術には、以下のような課題があった。
　すなわち、特許文献１や２に開示の技術では、メタルケースとガス通気性材質との間のモルタルについて、熱膨張率を向上させたとしても、モルタルの熱膨張量には限界がある。モルタルの膨張量以上にメタルケースが膨張してしまうと、メタルケースと耐火材質との間のガスリークを完全に防止することはできない課題があった。また、特許文献２のように、モルタルの熱膨張率を向上させるために発泡性の材質を使用すると、モルタル自体の緻密性が低下し、シール性を低下させる課題があった。 However, the above conventional technology has the following problems.
That is, in the techniques disclosed in Patent Documents 1 and 2, even if the thermal expansion coefficient of the mortar between the metal case and the gas-permeable material is improved, there is a limit to the amount of thermal expansion of the mortar. If the metal case expands beyond the amount of expansion of the mortar, there is a problem that gas leakage between the metal case and the refractory material cannot be completely prevented. Further, as in Patent Document 2, when a foamable material is used to improve the thermal expansion coefficient of mortar, the density of the mortar itself decreases, resulting in a problem of decreased sealing performance.
　また、特許文献３や４に開示の技術では、メタルケースの拘束力を向上させることで、物理的にメタルケースの熱膨張を抑止する方法も以下のような課題がある。特許文献３のように可撓性の耐火シールをメタルケース外周に巻く方法は、耐火シール材を巻いた部分については、メタルケースの熱変形を低減させる効果が期待されるが、他の部位については熱膨張を抑制できない。また、耐火シールを全体に巻いてしまうと、上ノズルと周囲のマスレンガとの接着性が低下し、上ノズルが上下にずれて動くため漏鋼リスクが増加するおそれがある。そのため、ガスリーク抑止方法としては十分であるとは言い難い。特許文献４のようにメタルケース外周にフィンを設置する方法であれば、メタルケース全体の熱変形を低減させる効果が期待できる。しかし、上ノズルを周囲のマスレンガ内にセットする作業の際に、フィンがマスレンガに接触してしまうような寸法にしてしまうと、マスレンガ自体を損傷させるおそれがある。そのため、上ノズルの挿入作業自体が困難となってしまう課題がある。一方、フィンの外径をマスレンガ内径よりも小さく設計してしまうと、強度向上の効果が小さくなり、メタルケースの熱膨張を完全に抑止することはできない課題があった。 Additionally, in the techniques disclosed in Patent Documents 3 and 4, the method of physically suppressing thermal expansion of the metal case by improving the binding force of the metal case also has the following problems. The method of wrapping a flexible fireproof seal around the outer periphery of a metal case as in Patent Document 3 is expected to be effective in reducing thermal deformation of the metal case in the part where the fireproof sealing material is wrapped, but it is not effective in reducing thermal deformation of the metal case in other parts. cannot suppress thermal expansion. Furthermore, if the fireproof seal is wrapped around the entire structure, the adhesion between the upper nozzle and the surrounding mass bricks will decrease, and the upper nozzle will shift vertically, which may increase the risk of steel leakage. Therefore, it cannot be said that this method is sufficient as a gas leak prevention method. A method of installing fins on the outer periphery of the metal case as in Patent Document 4 can be expected to have the effect of reducing thermal deformation of the entire metal case. However, when setting the upper nozzle into the surrounding mass bricks, if the dimensions are such that the fins come into contact with the mass bricks, there is a risk of damaging the mass bricks themselves. Therefore, there is a problem that the operation of inserting the upper nozzle itself becomes difficult. On the other hand, if the outer diameter of the fin is designed to be smaller than the inner diameter of the mass brick, the effect of improving strength will be reduced, and there is a problem that thermal expansion of the metal case cannot be completely suppressed.
　本発明は、上記した従来の課題を解決し、溶鋼の連続鋳造中にガス吹き上ノズルから不活性ガスを吹き込むにあたり、ガスリークが発生するのを防ぐことのできる技術を提供することを目的とする。ここで、ガスリークとはガス吹き上ノズルの外周に設けたメタルケースと耐火材質との間から、ガス通気性材質以外の部分に不活性ガスが流れ出ることをいう。 The present invention aims to solve the above-mentioned conventional problems and provide a technology that can prevent gas leaks when blowing inert gas from a gas blowing upper nozzle during continuous casting of molten steel. . Here, gas leak refers to inert gas flowing out from between the metal case provided on the outer periphery of the gas blowing upper nozzle and the refractory material to a portion other than the gas permeable material.
　上記課題を有利に解決する本発明にかかるガス吹き上ノズルは、ガス通気性材質（１Ｂ）を含む耐火材質（１）と、該耐火材質（１）の外周を囲繞するメタルケース（２）と、を備え、該メタルケース（２）の上端部から内側に延伸する上端メタルケース（３）を有し、前記耐火材質（１）と前記メタルケース（２）との間のシールモルタル部（４）上端が前記上端メタルケース（３）によって覆われていることを特徴とする。 The gas blowing nozzle according to the present invention, which advantageously solves the above problems, includes a fireproof material (1) including a gas permeable material (1B), and a metal case (2) surrounding the outer periphery of the fireproof material (1). , has an upper end metal case (3) extending inward from the upper end of the metal case (2), and has a sealing mortar part (4) between the refractory material (1) and the metal case (2). ) The upper end is covered by the upper end metal case (3).
　なお、本発明にかかるガス吹き上ノズルは、
（ａ）前記上端メタルケース（３）の延伸長さが、前記メタルケース（２）とマスレンガ（８）との間の目地厚以上であること、
（ｂ）前記上端メタルケース（３）の延伸した先端は前記耐火材質（１）の平坦な天端と上ノズル上部耐火材質（９）とに挟持されることによって覆い隠される範囲内にあること、
などがより好ましい解決手段になり得る。 In addition, the gas blowing nozzle according to the present invention is
(a) The extension length of the upper end metal case (3) is greater than or equal to the joint thickness between the metal case (2) and the mass brick (8);
(b) The extended tip of the upper end metal case (3) is within a range covered by being sandwiched between the flat top end of the refractory material (1) and the upper nozzle upper refractory material (9). ,
etc. may be a more preferable solution.
　上記課題を有利に解決する本発明にかかる連続鋳造方法は、上記いずれかのガス吹き上ノズルをタンディッシュ底部に設置し、前記ガス通気性材質に不活性ガスを吹き込みつつ、前記ガス吹き上ノズルを介してタンディッシュから鋳型に溶鋼を注入することを特徴とする。 A continuous casting method according to the present invention, which advantageously solves the above problems, includes installing any of the above gas blowing upper nozzles at the bottom of the tundish, and blowing an inert gas into the gas permeable material. It is characterized by injecting molten steel into the mold from the tundish through the tundish.
　本発明によるガス吹き上ノズルは、以上のように構成されているため、次のような効果を得ることができる。すなわち、ガス吹き上ノズルはガス通気性材質を含む耐火材質と上端メタルケースを有するメタルケースとによって形成されている。メタルケースの熱変形によって耐火材質とメタルケースとの間の目地に隙間が発生したとしても、上ノズル天端の目地を覆い隠すように配置された上端メタルケースが物理的にガスの漏洩経路を遮断する役目を果たす。そうすることで、ガスリークを防止することができるようになる。また、本発明にかかる連続鋳造方法は、上記ガス吹き上ノズルを介してタンディッシュから鋳型に溶鋼を注入するようにしたので、ガスリークなく連続鋳造することができ鋳片の品質を良好に維持できる。 Since the gas blowing nozzle according to the present invention is configured as described above, the following effects can be obtained. That is, the gas blowing upper nozzle is formed of a fireproof material including a gas permeable material and a metal case having an upper end metal case. Even if a gap occurs at the joint between the fireproof material and the metal case due to thermal deformation of the metal case, the upper metal case, which is placed to cover the joint at the top of the upper nozzle, physically prevents the gas leakage path. It plays the role of blocking. By doing so, gas leaks can be prevented. Further, in the continuous casting method according to the present invention, molten steel is injected into the mold from the tundish through the above-mentioned gas blowing nozzle, so continuous casting can be performed without gas leakage, and the quality of the slab can be maintained in good condition. .
本発明の一実施形態にかかるガス吹き上ノズルの縦断面図である。FIG. 1 is a longitudinal cross-sectional view of a gas blowing upper nozzle according to an embodiment of the present invention. （ａ）は上記実施形態のガス吹き上ノズルをタンディッシュに設置した概略断面図であり、（ｂ）はそのＡ部の部分拡大断面図である。(a) is a schematic cross-sectional view of the gas blowing upper nozzle of the above embodiment installed in a tundish, and (b) is a partially enlarged cross-sectional view of part A thereof. 上記実施形態のガス吹き上ノズルのメタルケースが熱膨張した状態を示す概念断面図である。It is a conceptual sectional view showing the state where the metal case of the gas blowing upper nozzle of the above-mentioned embodiment thermally expanded. （ａ）は従来のガス吹き上ノズルをタンディッシュに設置した概略断面図であり、（ｂ）はそのＢ部の部分拡大断面図であって、メタルケースが熱膨張した状態を示す概念断面図である。(a) is a schematic cross-sectional view of a conventional gas blowing nozzle installed in a tundish, and (b) is a partially enlarged cross-sectional view of part B thereof, which is a conceptual cross-sectional view showing a state in which the metal case is thermally expanded. It is. 上記実施形態のガス吹き上ノズルを用いて連続鋳造したときのガスリークの状況を従来例と比較して評価したグラフである。It is a graph evaluating the gas leak situation when continuous casting is performed using the gas blowing nozzle of the above embodiment in comparison with a conventional example.
　以下、本発明の実施の形態について具体的に説明する。なお、各図面は模式的なものであって、現実のものとは異なる場合がある。また、以下の実施形態は、本発明の技術的思想を具体化するための装置や方法を例示するものであり、構成を下記のものに特定するものでない。すなわち、本発明の技術的思想は、特許請求の範囲に記載された技術的範囲内において、種々の変更を加えることができる。 Hereinafter, embodiments of the present invention will be specifically described. Note that each drawing is schematic and may differ from the actual drawing. Furthermore, the following embodiments are intended to exemplify devices and methods for embodying the technical idea of the present invention, and the configuration is not limited to the following. That is, the technical idea of the present invention can be modified in various ways within the technical scope described in the claims.
　図１は、本発明の一実施形態にかかるガス吹き上ノズルの縦断面を示す図である。ガス吹き上ノズル１００の内部の耐火材質１は、回転軸（対称軸）ＣＬに沿って溶鋼が流通する貫通孔１１を有し、中空肉厚の回転体形状をなしている。貫通孔１１は上部に向かって朝顔状に広がっている。耐火材質１の天端（上端）に平坦部を持っている。そして、図１の例では、ガス非通気性材質１Ａとガス通気性材質１Ｂとの組み合わせで構成されている。ガス通気性材質１Ｂは任意の位置に配置することができる。ガス通気性材質１Ｂを配置した位置から貫通孔１１を通過する溶鋼内にガス吹込みを行うことができる。ガス非通気性材質１Ａも任意の位置に配置することができる。図１のように上下２か所から分割してガス吹きを行いたい場合には、ガス通気性材質１Ｂの境界部にガス非通気性材質１Ａを配置することで、吹分けを行うことが可能になる。なお、特にガスの吹分けを行う必要がない場合には、耐火材質１のすべてをガス通気性材質１Ｂとする構造としても問題はない。 FIG. 1 is a diagram showing a vertical cross section of a gas blowing upper nozzle according to an embodiment of the present invention. The refractory material 1 inside the gas blowing upper nozzle 100 has a through hole 11 through which molten steel flows along the rotation axis (axis of symmetry) CL, and has a hollow, thick-walled rotating body shape. The through hole 11 widens toward the top in a morning glory shape. The fireproof material 1 has a flat part at the top (upper end). In the example shown in FIG. 1, it is made of a combination of a gas non-permeable material 1A and a gas permeable material 1B. The gas permeable material 1B can be placed at any position. Gas can be injected into the molten steel passing through the through hole 11 from the position where the gas permeable material 1B is arranged. The gas-impermeable material 1A can also be placed at any position. If you want to blow gas separately from the upper and lower parts as shown in Figure 1, you can separate the blowing by placing the gas non-permeable material 1A at the boundary of the gas permeable material 1B. become. Note that, if there is no particular need to separate the gas, there is no problem in a structure in which all of the refractory material 1 is made of the gas-permeable material 1B.
　ガス通気性材質１Ｂへの不活性ガスの供給経路は、以下のように構成される。まず不活性ガス導入管６によってガス吹き上ノズル１００内に不活性ガスが導通される。その後、耐火材質１と、耐火材質１の外周を覆う略筒形状のメタルケース２との間に設けられたガスプール５を通過してガス通気性材質１Ｂへと到達する。図１の例ではガスプール５は耐火材質１とメタルケース２との間に設けられているが、耐火材質１内にスリットを設けてガスプール５を構成することもできる。ただし、本実施形態では、図１のように耐火材質１とメタルケース２との間にガスプール５が設けられた構造の方がより顕著にその効果を享受することができる。 The inert gas supply route to the gas permeable material 1B is configured as follows. First, an inert gas is introduced into the gas blow-up nozzle 100 through the inert gas introduction pipe 6 . Thereafter, the gas passes through a gas pool 5 provided between the refractory material 1 and a substantially cylindrical metal case 2 that covers the outer periphery of the refractory material 1, and reaches the gas permeable material 1B. In the example of FIG. 1, the gas pool 5 is provided between the refractory material 1 and the metal case 2, but the gas pool 5 can also be configured by providing a slit in the refractory material 1. However, in this embodiment, a structure in which a gas pool 5 is provided between the fireproof material 1 and the metal case 2 as shown in FIG. 1 can enjoy the effect more markedly.
　ガスプール５に到達した不活性ガスは、その全てがガス通気性材質１Ｂを通過して溶鋼中に吹き込まれることが必要である。不活性ガスがガス通気性材質１Ｂ以外の部位からガス吹き上ノズル１００の外に漏れ出ることをガスリークと呼ぶ。ガスリークが発生するとガス吹き上ノズル１００の中空部内の溶鋼に十分な量の不活性ガスが供給されなくなる。そのため、溶鋼清浄性向上に対する十分な効果が得られなくなる。その結果、鋳造した鋳片に品質上の問題が発生しうる。このようなガスリークを防止するため、耐火材質１とメタルケース２の間にはシールモルタル部４が配置されている。シールモルタル部４は耐火材質１とメタルケース２との間のガスプール５以外の隙間を埋めている。シールモルタル部４は、不活性ガスがガス吹き上ノズル１００の外に漏れ出すことを防止する役割を担っている。 It is necessary for all of the inert gas that has reached the gas pool 5 to pass through the gas permeable material 1B and be blown into the molten steel. The leakage of inert gas to the outside of the gas blowing nozzle 100 from a portion other than the gas permeable material 1B is called a gas leak. If a gas leak occurs, a sufficient amount of inert gas will not be supplied to the molten steel in the hollow part of the gas blowing nozzle 100. Therefore, a sufficient effect on improving the cleanliness of molten steel cannot be obtained. As a result, quality problems may occur in the cast slab. In order to prevent such gas leaks, a seal mortar section 4 is disposed between the refractory material 1 and the metal case 2. The seal mortar part 4 fills the gap between the refractory material 1 and the metal case 2 except for the gas pool 5. The seal mortar portion 4 plays a role in preventing inert gas from leaking out of the gas blow-up nozzle 100.
　本実施形態のガス吹き上ノズル１００をタンディッシュ内にセットした際の模式図を図２（ａ）に示す。ガス吹き上ノズル１００の周囲は、タンディッシュ鉄皮７、マスレンガ８、上ノズル上部耐火材質９に囲まれている。ガス吹き上ノズル１００は周囲の各材質によって拘束される。マスレンガ８とメタルケース２との間の目地には上ノズルセットモルタル１０を配置し、隙間が空かないよう工夫されている。ガス吹き上ノズル１００への拘束力は、マスレンガ８と上ノズルセットモルタル１０とメタルケース２との接着力によって保証されている。 A schematic diagram of the gas blowing upper nozzle 100 of this embodiment set in a tundish is shown in FIG. 2(a). The gas blowing upper nozzle 100 is surrounded by a tundish iron skin 7, a mass brick 8, and a refractory material 9 above the upper nozzle. The upper gas blowing nozzle 100 is restrained by surrounding materials. An upper nozzle set mortar 10 is arranged at the joint between the mass brick 8 and the metal case 2, so that no gap is left. The binding force to the gas blowing upper nozzle 100 is guaranteed by the adhesive force between the mass brick 8, the upper nozzle set mortar 10, and the metal case 2.
　図２（ａ）の二点鎖線部Ａで囲んだガス吹き上ノズル１００の上端部を拡大して図２（ｂ）に示す。本実施形態では、メタルケース２の上端部から内側に延伸する上端メタルケース３を有している。耐火材質１とメタルケース２との間のシールモルタル部４（目地部）の上端が上端メタルケース３によって覆われている構成としている。メタルケース２の上端外周と上端メタルケース３との連結は、たとえば、溶接やかしめとし、あるいは、メタルケース２と上端メタルケース３とを絞り成形などで一体成形してもよい。また、上端メタルケース３は耐火材質１の天端の平坦部に沿う円環状とすることが好ましい。ガス吹き上ノズル１００の上端部に上端メタルケース３を配置し、上端メタルケース３と上ノズル外周のメタルケース２との間は隙間なく連結された状態にする。そうすることで、メタルケース２に熱変形が生じても、耐火材質１とメタルケース２との目地からのガスリークを抑制することができる。すなわち、図３に示すような熱変形（矢印で示す）が生じても、耐火材質１とメタルケース２との目地に生じるガスリーク経路を上端メタルケース３およびシールモルタル部４が塞いでおり、ガスリーク経路を物理的に遮断することができる。この際、メタルケース２が熱変形によって開く限界長さは、メタルケース２とマスレンガ８との間の目地厚に依存する。したがって、メタルケース２が最大の熱変形を起こしてもガスリークを防止する効果を持たせるために、上端メタルケース３の延伸長さはメタルケース２とマスレンガ８との間の目地厚以上にすることが好ましい。また、上端メタルケース３は溶鋼と直接接触すると溶解し、その形状を保てなくなる。そのため、上端メタルケース３の延伸長さは、最大でもガス吹き上ノズルの耐火材質１の平坦な天端と上ノズル上部耐火材質９とに挟持されることによって覆い隠される範囲内に収めることが好ましい。ここで、上端メタルケース３の延伸長さは、回転軸ＣＬを中心軸とする円筒座標系における半径方向の長さとする。 FIG. 2(b) shows an enlarged view of the upper end of the gas blowing upper nozzle 100, which is surrounded by the chain double-dashed line section A in FIG. 2(a). This embodiment has an upper end metal case 3 extending inward from the upper end of the metal case 2 . The upper end of the seal mortar part 4 (joint part) between the refractory material 1 and the metal case 2 is covered by the upper end metal case 3. The upper end outer periphery of the metal case 2 and the upper end metal case 3 may be connected, for example, by welding or caulking, or the metal case 2 and the upper end metal case 3 may be integrally formed by drawing or the like. Further, it is preferable that the upper end metal case 3 has an annular shape along the flat part of the top end of the refractory material 1. An upper end metal case 3 is arranged at the upper end of the upper gas blowing nozzle 100, and the upper end metal case 3 and the metal case 2 on the outer periphery of the upper nozzle are connected without a gap. By doing so, even if thermal deformation occurs in the metal case 2, gas leakage from the joint between the fireproof material 1 and the metal case 2 can be suppressed. That is, even if thermal deformation (indicated by the arrow) as shown in FIG. 3 occurs, the upper end metal case 3 and the seal mortar part 4 block the gas leak path that occurs at the joint between the refractory material 1 and the metal case 2, and the gas leak does not occur. The route can be physically blocked. At this time, the limit length in which the metal case 2 opens due to thermal deformation depends on the joint thickness between the metal case 2 and the mass bricks 8. Therefore, in order to have the effect of preventing gas leakage even if the metal case 2 undergoes maximum thermal deformation, the extension length of the upper end metal case 3 should be greater than the joint thickness between the metal case 2 and the mass brick 8. is preferred. Furthermore, if the upper end metal case 3 comes into direct contact with molten steel, it will melt and will no longer be able to maintain its shape. Therefore, the extension length of the upper end metal case 3 can be kept within the range covered by being sandwiched between the flat top end of the refractory material 1 of the gas blowing upper nozzle and the upper nozzle upper refractory material 9 at most. preferable. Here, the extended length of the upper end metal case 3 is defined as the length in the radial direction in a cylindrical coordinate system having the rotation axis CL as the central axis.
　耐火材質１は、たとえば、ハイアルミナ系材料であり、メタルケース２および上端メタルケース３は、金属質であって、たとえば、炭素鋼、合金鋼、ステンレス鋼、鋳鋼、鋳鉄、チタンおよびチタン合金などが好適に用いられる。シールモルタル部４や上ノズルセットモルタル１０は、たとえば、ハイアルミナ質の水練りのモルタルを適度の稠度に調整して用いることができる。メタルケース（２）とマスレンガ（８）との間の目地厚は１～５ｍｍ程度である。ガス吹き上ノズル１００の耐火材質１の平坦な天端と上ノズル上部耐火材質９とに挟持される範囲は、回転軸ＣＬからの半径方向長さで５～２０ｍｍ程度である。 The refractory material 1 is, for example, a high alumina material, and the metal case 2 and the upper end metal case 3 are made of metal, such as carbon steel, alloy steel, stainless steel, cast steel, cast iron, titanium, and titanium alloy. is preferably used. The seal mortar part 4 and the upper nozzle set mortar 10 can be made of, for example, high alumina water-mixed mortar adjusted to an appropriate consistency. The thickness of the joint between the metal case (2) and the mass brick (8) is about 1 to 5 mm. The range sandwiched between the flat top end of the refractory material 1 of the gas blowing upper nozzle 100 and the upper nozzle upper refractory material 9 is about 5 to 20 mm in radial length from the rotation axis CL.
　本発明の他の実施形態としての連続鋳造方法では、上記実施形態のガス吹き上ノズル１００を図２に示すようにタンディッシュ底部に設置する。そして、不活性ガス導入管６から導入した不活性ガスを、ガス通気性材質１Ｂを通じて貫通孔１１を流下する溶鋼内に流す。タンディッシュ内溶鋼は、そのガス吹き上ノズル１００に加えて、必要に応じて、スライディングノズルや浸漬ノズルを介して鋳型に注入される。上記実施形態のガス吹き上ノズル１００を用いて、連続鋳造することにより、連々を続けて鋳造した場合であっても、ガス吹き上ノズル１００のメタルケース２の熱膨張による変形に起因したガスリークを防止できるようになる。上端メタルケース３がガス吹き上ノズル１００の天端を覆う範囲は、メタルケース２の熱変形にもかかわらず、耐火材質１とメタルケース２との目地であるシールモルタル部４が外部に露出しないように覆う必要がある。そのように構成することで、ガスリークを防止できる。 In a continuous casting method as another embodiment of the present invention, the gas blowing upper nozzle 100 of the above embodiment is installed at the bottom of the tundish as shown in FIG. 2. Then, the inert gas introduced from the inert gas introduction pipe 6 is caused to flow into the molten steel flowing down through the through hole 11 through the gas permeable material 1B. The molten steel in the tundish is injected into the mold via the gas blowing nozzle 100 and, if necessary, a sliding nozzle or a submerged nozzle. By performing continuous casting using the gas blowing upper nozzle 100 of the above embodiment, gas leakage caused by deformation due to thermal expansion of the metal case 2 of the gas blowing upper nozzle 100 can be prevented even when continuous casting is performed. This can be prevented. In the range where the upper end metal case 3 covers the top end of the gas blowing upper nozzle 100, the seal mortar portion 4, which is the joint between the fireproof material 1 and the metal case 2, is not exposed to the outside despite thermal deformation of the metal case 2. It is necessary to cover it like this. With such a configuration, gas leaks can be prevented.
　図１および図２に示す本実施形態および図４に示す従来のガス吹き上ノズルをタンディッシュ底部に設置して連続鋳造し、ガス吹き上ノズルに吹き込んだ不活性ガスの背圧でガスリークの有無を評価した結果を図５に示す。ガスリークが発生したか否かはガス吹き上ノズルに導通させている不活性ガスの背圧を監視することで判定することができる。すなわち、不活性ガスが正常にガス通気性材質１Ｂから溶鋼内に吹き込まれた場合には、不活性ガスの背圧は溶鋼静圧とガス通気性材質１Ｂの通気抵抗との合算の抵抗圧力を受け、その抵抗圧力は背圧として現れる。しかし、ガスリークが発生した場合は、少なくともガス通気性材質１Ｂの通気抵抗が発生しなくなることから、その背圧は低下する。そこで、ガスリークが発生したか否かの判定としては背圧低下発生有無で判定することとし、本実施形態および従来のガス吹き上ノズルの効果検証を行った。 The present embodiment shown in FIGS. 1 and 2 and the conventional gas blowing upper nozzle shown in FIG. 4 are installed at the bottom of the tundish and continuous casting is performed, and whether there is any gas leakage due to the back pressure of the inert gas blown into the gas blowing upper nozzle. The results of the evaluation are shown in Figure 5. Whether or not a gas leak has occurred can be determined by monitoring the back pressure of the inert gas flowing through the upper gas blowing nozzle. In other words, when the inert gas is normally blown into the molten steel from the gas-permeable material 1B, the back pressure of the inert gas is equal to the resistance pressure that is the sum of the static pressure of the molten steel and the ventilation resistance of the gas-permeable material 1B. The resistance pressure appears as back pressure. However, when a gas leak occurs, the back pressure decreases because at least the gas permeable material 1B no longer generates ventilation resistance. Therefore, whether or not a gas leak has occurred is determined based on the presence or absence of a decrease in back pressure, and the effects of the present embodiment and the conventional gas blow-up nozzle were verified.
　ここで、判定に用いた背圧の閾値は、鋳造設備や操業度によって左右されるため、個別の連鋳機で最適化する必要がある。今回判定を行った連鋳機では、定常時の背圧に対して約３割の背圧低下が発生したものを背圧低下と呼んで判定を行った。図５に示すように、従来のガス吹き上ノズル（従来例：Ｎ＝１０１２）を使用した場合は背圧低下が０．０１８の発生率であった。一方、本実施形態（発明例：Ｎ＝１０７）を適用することで背圧低下、つまりガスリークの発生を抑止することができた。 Here, the back pressure threshold used for determination depends on the casting equipment and operating rate, so it needs to be optimized for each individual continuous casting machine. In the continuous casting machine that was evaluated this time, a reduction in back pressure of approximately 30% compared to the normal back pressure was referred to as a reduction in back pressure. As shown in FIG. 5, when a conventional gas blowing nozzle (conventional example: N=1012) was used, the incidence of back pressure drop was 0.018. On the other hand, by applying this embodiment (inventive example: N=107), it was possible to suppress the back pressure drop, that is, the occurrence of gas leak.
　本発明のガス吹き上ノズルおよび連続鋳造方法によれば、吹き込んだ不活性ガスをガスリークなく溶鋼に吹き込みながら連続鋳造できるので、鋳片の品質を良好に維持でき、産業上有用である。 According to the gas blowing nozzle and continuous casting method of the present invention, continuous casting can be performed while blowing the inert gas into the molten steel without gas leakage, so the quality of the slab can be maintained at a good level, which is industrially useful.
１００　ガス吹き上ノズル（上ノズル）
　１　耐火材質
　１Ａ　ガス非通気性材質
　１Ｂ　ガス通気性材質
　２　メタルケース
　３　上端メタルケース
　４　シールモルタル部
　５　ガスプール（ガス流路）
　６　不活性ガス導入管
　７　タンディッシュ鉄皮
　８　マスレンガ
　９　上ノズル上部耐火材質
１０　上ノズルセットモルタル
１１　貫通孔
ＣＬ　回転軸（対称軸） 100 Gas blowing upper nozzle (upper nozzle)
1 Fireproof material 1A Gas non-permeable material 1B Gas permeable material 2 Metal case 3 Upper end metal case 4 Seal mortar part 5 Gas pool (gas flow path)
6 Inert gas introduction pipe 7 Tundish shell 8 Mass brick 9 Upper nozzle upper refractory material 10 Upper nozzle set mortar 11 Through hole CL Rotation axis (symmetrical axis)

Claims (4)

  1. ガス通気性材質（１Ｂ）を含む耐火材質（１）と、
    該耐火材質（１）の外周を囲繞するメタルケース（２）と、
    を備え、
    該メタルケース（２）の上端部から内側に延伸する上端メタルケース（３）を有し、
    前記耐火材質（１）と前記メタルケース（２）との間のシールモルタル部（４）上端が前記上端メタルケース（３）によって覆われている、ガス吹き上ノズル。     a fire-resistant material (1) including a gas-permeable material (1B);
    a metal case (2) surrounding the outer periphery of the fireproof material (1);
    Equipped with
    It has an upper end metal case (3) extending inward from the upper end of the metal case (2),
    A gas blowing upper nozzle, wherein an upper end of a seal mortar part (4) between the refractory material (1) and the metal case (2) is covered by the upper end metal case (3).
  2. 前記上端メタルケース（３）の延伸長さが、前記メタルケース（２）とマスレンガ（８）との間の目地厚以上である、請求項１に記載のガス吹き上ノズル。 The gas blowing upper nozzle according to claim 1, wherein the extension length of the upper end metal case (3) is greater than or equal to the joint thickness between the metal case (2) and the mass brick (8).
  3. 前記上端メタルケース（３）の延伸した先端は前記耐火材質（１）の平坦な天端と上ノズル上部耐火材質（９）とに挟持されることによって覆い隠される範囲内にある、請求項２に記載のガス吹き上ノズル。 Claim 2, wherein the extended tip of the upper end metal case (3) is within a range covered by being sandwiched between the flat top end of the refractory material (1) and the upper nozzle upper refractory material (9). The gas blowing nozzle described in .
  4. 請求項１ないし３のいずれか一項に記載のガス吹き上ノズルをタンディッシュ底部に設置し、前記ガス通気性材質に不活性ガスを吹き込みつつ、前記ガス吹き上ノズルを介してタンディッシュから鋳型に溶鋼を注入する、連続鋳造方法。
          The upper gas blowing nozzle according to any one of claims 1 to 3 is installed at the bottom of the tundish, and while blowing an inert gas into the gas permeable material, the mold is removed from the tundish through the upper gas blowing nozzle. A continuous casting method in which molten steel is injected into the steel.
PCT/JP2023/018626 2022-05-27 2023-05-18 Gas blowing-up nozzle and continuous casting method WO2023228864A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0184859U (en) * 1987-11-27 1989-06-06
JPH0342351U (en) * 1989-08-29 1991-04-22
JP2001334360A (en) * 2000-05-22 2001-12-04 Shinagawa Refract Co Ltd Flow regulating nozzle and method for manufacturing the same

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0184859U (en) * 1987-11-27 1989-06-06
JPH0342351U (en) * 1989-08-29 1991-04-22
JP2001334360A (en) * 2000-05-22 2001-12-04 Shinagawa Refract Co Ltd Flow regulating nozzle and method for manufacturing the same

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