Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
  • B22D41/50—Pouring-nozzles
• • 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
  • B22D41/52—Manufacturing or repairing thereof
  • B22D41/54—Manufacturing or repairing thereof characterised by the materials used therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/10—Supplying or treating molten metal
  • B22D11/103—Distributing the molten metal, e.g. using runners, floats, distributors
• • 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
  • B22D41/502—Connection arrangements; Sealing means therefor
• • 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
  • B22D41/52—Manufacturing or repairing thereof
• • 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 the casting of steel slabs and more specifically to upper tundish nozzles used in such casting. Most specifically, the invention relates to argon injected upper tundish nozzle designs by which argon leakage therefrom is minimized/eliminated.
• the present invention relates to an improved design for upper tundish nozzle.
• the nozzle is designed to be used in continuous casting of steel into slabs.
• Figure 1 depicts a cross section of such a continuous casting line.
• the line includes a ladle 1 which continuously brings fresh steel to the tundish 2.
• the tundish 2 controls the flow therefrom into the casting mold 3.
• Figure 2 is a closer view of the tundish 2 and the casting mold 3 and specifically shows the position of the upper tundish nozzle 4, which is the focus of the present invention.
• the upper tundish nozzle 4 collects the molten steel from the tundish 2 and directs the steel through a gate valve and into the casting mold 3.
• FIG 3 is a simplified cross section of an upper tundish nozzle 4.
• the upper tundish nozzle 4 is composed of a ceramic inner portion 6 and a protective can 5 which houses and protects the fragile ceramic inner portion 6.
• the ceramic inner portion 6 of such nozzles are often formed from a porous, gas permeable refractory material which may be a ceramic oxide of aluminum, silicon, magnesium, chromium, or zirconium, or mixtures thereof.
• the ceramic inner portion 6 of the nozzle may be formed of a ceramic material having pierced/tunneled holes in the ceramic to provide set gas flow paths within the ceramic inner portion 6.
• the porous, gas permeable refractory material and/or the pierced/tunneled holes provide flow paths for Argon gas which is injected into the upper tundish nozzle 4 during continuous casting to deter clogging of the upper tundish nozzle 4 with solid inclusions.
• the argon flow also affects the flow pattern of steel in the upper tundish nozzle 4, the gate valve and subsequently in the casting mold 3.
• the inside surface of the ceramic inner portion 6 of the upper tundish nozzle 4 defines a bore for conducting a flow of liquid steel.
• the outside surface of the ceramic inner portion 6 is enveloped in a protective can 5.
• the protective can 5 can be formed of metallic sheet material, such as steel, that may be spaced apart from the outside surface of the ceramic inner portion 6 in order to define one or more annular, gas conducting spaces.
• the argon gas is injected into the upper tundish nozzle 4 via a gas injection port 7.
• Figure 3 indicates the argon gas injection port 7, as well as the argon flow path 8 in an upper tundish nozzle 4 having a porous ceramic inner portion 6.
• inert gas such as argon
• inert gas such as argon
• the inert gas flows through the gas flow paths 8 in the porous ceramic inner portion 6.
• the argon eventually escapes the porous ceramic inner portion 6 as argon bubbles 9.
• These bubbles may advantageously form a fluid film over the surface of the bore within the upper tundish nozzle 4 that prevents that molten metal from making direct contact with the inner surface forming the bore.
• the fluid film of gas prevents the small amounts of alumina that are present in such steel from sticking to and accumulating onto the surface of the nozzle bore.
• the prevention of such alumina deposits is important, as such deposits will ultimately obstruct the flow of molten steel until it congeals around the walls of the bore, thereby clogging the upper tundish nozzle 4.
• Such a clogged nozzle 4 necessitates the shutting down of the casting process and the replacement of the nozzle 4.
• the pressure of the inert gas must be maintained at a level high enough to overcome the considerable backpressure that the molten steel applies to the surface of the bore. Ideally, the gas pressure should be just enough to form the desired film. If it is too high, the gas can stir the steel excessively, thus creating additional defects. Thus, the control of the gas pressure and flow is critical and must be maintained within a narrow range. Any significant leak can jeopardize the desired delicate pressure balance. Further such argon loss is an added expense to production and therefore should be minimized if possible.
• the present invention relates to a leak-proof gas injected upper tundish nozzle.
• the nozzle includes a protective can and a ceramic inner portion disposed within the protective can.
• the ceramic inner portion preferably has gas flow pathways therein.
• the nozzle further includes a gas injection port attached to the protective can which allows for the injection of gas through the protective can and into gas flow pathways within the ceramic inner portion.
• the nozzle also includes at least one gas flow seal formed between the protective can and the ceramic inner portion.
• the gas flow seal blocks gas leakage from the gap between the protective can and the ceramic inner portion.
• the gas flow seal may be formed from nickel or an alloy of nickel.
• the gas flow seal may be formed by depositing nickel or nickel alloy into any gaps between the protective can and the ceramic inner portion by a method selected from the group consisting of electroplating, electroless plating, nickel/alloy foil strips, sputtering, plasma vapor deposition, and metal printing.
• the gas flow seal may be formed by electroplating nickel or nickel alloy into any gaps between the protective can and the ceramic inner portion.
• the nickel or nickel alloy may be electroplated across the gap on the exterior of the protective can and the exterior of ceramic inner portion.
• the nickel or nickel alloy may be electroplated across the gap on the exterior of the protective can and the exterior of the ceramic inner portion after the protective can and ceramic inner portion have been formed into a unitary piece.
• the nickel or nickel alloy may be deposited onto one or both of the interior surface of the protective can and the exterior surface of the ceramic inner portion.
• the nickel or nickel alloy may be deposited onto one or both of the interior surface of the protective can and the exterior surface of the ceramic inner portion before the protective can and ceramic inner portion have been formed into a unitary piece.
• the protective can may be formed of a metal material, preferably steel.
• the ceramic inner portion may be formed from a porous ceramic material and the gas flow pathways may comprise the pores within the porous ceramic material.
• the ceramic inner portion may be is formed from a gas permeable refractory material consisting of a ceramic oxide of one or more of aluminum, silicon, magnesium, chromium, or zirconium, or mixtures thereof.
• the ceramic inner portion may not be porous or gas permeable and the gas flow pathways may be formed directly into the body of the ceramic inner portion.
• the gas flow pathways may include a gas distribution manifold and gas distribution channels.
• the gas distribution channels may have gas outlets to release the gas into the steel flowing within the upper tundish nozzle.
• Figure 1 depicts a cross section of a continuous casting line in which the upper tundish nozzle of the present is preferably used;
• Figure 2 is a closer view of the tundish and the casting mold and specifically shows the position of the upper tundish nozzle;
• Figure 3 is a simplified cross section of an upper tundish nozzle
• Figure 4 depicts a typical cross-sectional view of an upper tundish nozzle and specifically indicates gaps through which gas may leak;
• Figure 5 depicts a cross-sectional view of an upper tundish nozzle including the inventive gap seal solution.
• the present invention is an improved argon injected upper tundish nozzle 4 which minimizes/eliminates unwanted leakage of inert gas (such as argon) therefrom.
• Figure 4 depicts a typical cross-sectional view of an upper tundish nozzle 4.
• the figure indicates the main components such as the protective can 5, the ceramic inner portion 6, the argon injection port 7 and the argon gas flow path 8 within the ceramic inner portion 6.
• the ceramic inner portion 6 may or may not be porous, but the argon flow path 8 (including a gas distribution manifold and gas distribution channels which include gas outlets to release the gas into the bore of the nozzle) is molded into the ceramic inner portion 6 during production.
• the ceramic inner portion 6 may alternatively be formed of a porous ceramic without pre-made gas flow paths 8.
• Figure 4 also depicts the problems addressed by the present invention.
• the leakage paths 10 can be at the top and bottom gaps.
• the inner ceramic portion 6 is press formed into the protective can 5 thereby forming a unitary piece. Due to the difference in thermal expansion between the metal protective can 5 and the ceramic inner portion 6, it is very difficult, if not impossible to for a gas tight seal between them. While these gaps may seem small and insignificant, it should be noted that for a typical upper tundish nozzle 4, a gap of 0.04318 mm between the protective can 5 and the ceramic inner portion 6 has the same flow area as a 3.175 mm pipe. This can result in significant loss of argon volume and pressure.
• Figure 5 depicts the inventive solution devised by the present inventors.
• the inventors have found that a seal 11 , 11' between the protect can 5 and the ceramic inner portion 6 can plug the leaks of argon.
• the seal 11 , 11 ' is formed of nickel or a nickel alloy.
• the temperature at the interface between the protective can 5 and the ceramic inner portion 6 is lower than the melting point of the nickel/alloy seal 11 , 11 '. It is believed that this seal 11 ,1 T remains ductile at the elevated temperatures within the gap and stretches without cracking during expansion of the protective can 5 and the ceramic inner portion. This helps to prevent the gaps from leaking.
• the can with the electroplated nickel seals 11 , 1 T was subjected to thermal testing by pouring liquid steel into the nozzle using a 100 lb open air furnace. The pour went from a ladle through the upper tundish nozzle 4 into an ingot mold under the nozzle. After the steel solidified, the nozzle was examined, and it was found that the electroplated nickel seal 11 ,11 ’ was completely intact and even survived a direct metal splash.
• the first type of nickel seal 11 is described above. It is applied externally to cover the gaps between the protective can 5 and the ceramic inner portion 6. This type of seal 11 is generally applied after the upper tundish nozzle 4 is formed.
• the nickel material may be applied to one or both of the protective can 5 and the ceramic inner portion 6 before the upper tundish nozzle 4 is formed.
• the nickel is deposited strategically on the protective can 5 and/or ceramic inner portion 6 to form the nickel seal 1 T there between.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Continuous Casting (AREA)
• Casting Support Devices, Ladles, And Melt Control Thereby (AREA)

Priority Applications (7)

Applications Claiming Priority (1)

Publications (1)

Family

ID=78032469

Family Applications (1)

Country Status (7)

Citations (4)

• 2021
  • 2021-09-24 CN CN202180102327.8A patent/CN117940234A/zh active Pending
  • 2021-09-24 JP JP2024518366A patent/JP2024533667A/ja active Pending
  • 2021-09-24 WO PCT/IB2021/058717 patent/WO2023047153A1/en active Application Filing
  • 2021-09-24 EP EP21783591.7A patent/EP4405122A1/en active Pending
  • 2021-09-24 CA CA3232437A patent/CA3232437A1/en active Pending
  • 2021-09-24 KR KR1020247011341A patent/KR20240060805A/ko unknown
  • 2021-09-24 MX MX2024003545A patent/MX2024003545A/es unknown

Patent Citations (4)

Also Published As

Similar Documents

Legal Events