EP1133373B1 - Verbesserungen an oder in bezug auf feuerfestprodukte - Google Patents

Verbesserungen an oder in bezug auf feuerfestprodukte Download PDF

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Publication number
EP1133373B1
EP1133373B1 EP99963335A EP99963335A EP1133373B1 EP 1133373 B1 EP1133373 B1 EP 1133373B1 EP 99963335 A EP99963335 A EP 99963335A EP 99963335 A EP99963335 A EP 99963335A EP 1133373 B1 EP1133373 B1 EP 1133373B1
Authority
EP
European Patent Office
Prior art keywords
ceramic
refractory device
pouring tube
refractory
metallic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP99963335A
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English (en)
French (fr)
Other versions
EP1133373A1 (de
Inventor
Stephen John Lee
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Didier Werke AG
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Didier Werke AG
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Publication date
Application filed by Didier Werke AG filed Critical Didier Werke AG
Publication of EP1133373A1 publication Critical patent/EP1133373A1/de
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Publication of EP1133373B1 publication Critical patent/EP1133373B1/de
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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
    • B22D41/14—Closures
    • B22D41/22—Closures sliding-gate type, i.e. having a fixed plate and a movable plate in sliding contact with each other for selective registry of their openings
    • B22D41/28—Plates 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

Definitions

  • This invention relates to improvements in or relating to refractory products and, more particularly, to improvements in refractory products used in the handling of molten metals to increase reliability under high temperature operating conditions.
  • Metal teeming, and in particular the casting of steel usually begins with the metal being melted and transferred to a vessel, e.g, a ladle or tundish.
  • Refractory devices are required, amongst other things, for the regulation of the flow of the molten metal exiting from a nozzle mounted in the bottom of the vessel. In the casting of steel, this is typically applied through an opening in the base of the vessel via nozzles and shrouds into a water-cooled mould.
  • Refractory devices such as sub-entry shrouds and pouring nozzles are often at least partly submerged for long periods of time in the molten metal during the metal teeming process and are therefore subject to high temperatures and stresses during the effective lifetime of the device.
  • a flow control valve is provided in the tundish comprising a flow control stopper rod selectively engageable with an outlet nozzle seat.
  • the stopper would normally be raised off the seat by a certain amount to achieve a particular rate of flow of molten metal through the valve to ultimately cast a product in a mould.
  • the teeming apparatus would usually include a pouring nozzle or a shroud located beneath the flow control valve either of which may be immersed in melt as the casting operation proceeds.
  • the exchange pouring nozzle or shroud is supported beneath a stopper upper nozzle and stationary plate assembly which is used for sealing off the flow of molten metal above the pouring nozzle or shroud to allow the pouring nozzle or shroud to be changed during the teeming process.
  • EP-A-0 149 164 discloses a refractory pouring device comprising a ceramic body having a ceramic pouring tube element and a ceramic support tube element. Between said elements there is provided a stock - absorbing interface zone comprising a material being deformable at elevated temperatures.
  • EP-A-0 346 378 describes the development of a monotube configuration and compares that to a two part plate and tube assembly generally known and used within an exchange nozzle casting mechanism as described above.
  • the pouring tube element combines a body of high thermal shock resistance and corrosion resistance with a sliding plate surface able to form a tight closure against the stationary components of the mechanism.
  • the sliding plate surface also incorporates a hard edge to permit cutting through any metal skin which may form during the casting operation and which may restrict free movement of the exchange monotube during the replacement procedure.
  • compositions for the pouring tube element have been developed making it possible to maintain the plate surface and cutting edge configuration whilst providing improved corrosion and erosion resistance.
  • These improved materials for the pouring tube element of a monotube do however exhibit different thermo-mechanical properties from the original materials as shown in the following table: MONOTUBE POURING TUBE ELEMENT COMPOSITIONS CONVENTIONAL HIGH CORROSION RESISTANCE 40 Al2O3% 64 18 SiO2% 6 28 C% 24 8 ZrO2% 6 4 SiC% - 2.38 Bulk density g/ml 2.6 0.35 Thermal Expansion% 0-1000 0.52
  • thermo mechanical stresses arising at the outset of casting can cause an external micro-crack fracture at the section change between the head and body portions of the pouring tube.
  • this micro-crack feature is contained by the inherent integrity of the ceramic body. This results in no operational problem, but in extreme cases it is possible for the external micro-crack fracture to propagate across the ceramic wall of the tube to the inner bore. This allows either air ingress or metal leakage, both of which cause termination of the cast and possible damage to the exchange nozzle casting mechanism.
  • An object of this invention is to obviate or mitigate the risks of exaggerated thermo mechanical stresses in the new generation of pouring tube elements, and this is found to be achievable by revising both the design of the pouring tube element and the manner in which it is contained within the can. It will be recalled that location of the refractory within the support can requires care to provide the correct geometrical configuration to allow effective operation of the exchange tube mechanism and maintain the principle of no direct horizontal connection from the bore to the exterior other than the machined sliding surface.
  • a refractory device for use in the teeming of molten metal comprising a ceramic pouring tube element supported in a metallic can, in which a ceramic support element, is encapsulated and a shock - absorbing interface zone between said metallic can and the ceramic pouring tube element, in which zone there is provided a material the thermal properties of which are such that it is substantially solid at ambient temperatures but becomes deformable at the elevated temperatures experienced during metal teeming.
  • the interface zone provides continuity of mechanical support to the body portion when in the substantially solid (cool ambient temperature) condition to ensure structural integrity of the assembled refractory device, but deforms sufficiently to provide a buffer against sudden differential thermal stresses, thereby minimising the risks of micro-crack fracture through the body portion due to thermo mechanical stresses during pre-heat and at the start of the casting operation.
  • the material selected for use in the interface zone is structurally solid at temperatures up to about 700°C and becomes deformable without any appreciable chemical degradation at temperatures above about 700°C.
  • the material providing the interface zone comprises a pyroplastic ceramic material.
  • the interface zone comprises a ceramic material such as a paste or bonding agent or additional structural ceramic element exhibiting the aforesaid properties.
  • the pyroplastic material is a frittable composition applied over at least one of the co-operating assembly surfaces of the pouring tube element and the metallic can.
  • the ceramic support element is normally fully encapsulated within the metallic can, and fits with and around the upper part of the pouring tube element by virtue of said ceramic support element having an internal profile corresponding sufficiently to the external profile of the pouring tube.
  • the respective profiles are such as to provide corresponding interference fit surfaces or otherwise matching, e.g. tapering surfaces to facilitate assembly, and in-fill or insertion of the required shock-absorbing interface zone material.
  • the ceramic support element may be pre-formed from a ceramic material of low thermal conductivity, or formed in situ by a suitable casting operation of a type familiar to those in this art.
  • the refractory device may be otherwise finished as is known in the art to suit its intended purpose, e.g. with regard to provision of flat surfaces and outlet nozzles etc.
  • FIGS 1-3 cross-sectional views of prior art refractory devices including the two-part plate and tube assembly known generally in the prior art and the early monotube configuration discussed above.
  • FIG. 6 is a cross-sectional view of a refractory product according to one aspect of the present invention.
  • a refractory pouring device having a ceramic pouring tube element 10 such as for example of a pouring nozzle or sub entry shroud.
  • the pouring tube element is supported in a metallic can 11 , which maintains the desired geometrical configuration of the tube for mechanical integrity of the pouring mechanism.
  • a low thermal conductivity ceramic support element 12 is encapsulated within the metallic can, and fits with and around the upper part of the pouring tube element, by virtue of said ceramic support element having an internal profile corresponding sufficiently to the external profile of the pouring tube.
  • a stepped shoulder, interference fit arrangement is illustrated.
  • the low thermal conductivity of the ceramic support element reduces heat losses from the pouring tube during metal teeming thereby minimising the differential thermal stresses experienced by the pouring tube which could lead to propagation of stress micro-crack features.
  • a shock absorbing interface zone 13 is formed between the low conductivity ceramic support element 12 and the pouring tube element 10.
  • the zone is formed in accordance with one aspect of the invention by a layer of pyroplastic ceramic cement, the properties of which are chosen to provide optimum mechanical strength in temperatures below about 700°C to support the pouring tube during preheating operations and manipulation.
  • the cement has a degree of pyroplasticity at elevated temperatures encountered during use of the pouring tube in the metal teeming process to absorb any residual differential stresses, which may be created during this process.
  • the pyroplastic ceramic cement may be formed from an alumina-silicate mixture with an addition of fluxing agents to generate the pyroplastic behaviour.
  • a typical analysis of said pyroplastic cement being alumina 20%, silica 54%, potassium oxide 6%, boric oxide 12% and sodium oxide 8%.
  • Such a composition will provide for progressive melting from about 700°C to impart plasticity to the layer.
  • Figure 7 illustrates a further embodiment of the present invention wherein the pouring tube element 20 is coated with a pyroplastic surface layer 24 on its upper region to provide the desired low temperature rigidity and high temperature malleability.
  • the coated tube is then encapsulated within the metallic can 21 by a ceramic concrete 22, which provides mechanical support to the pouring tube during the teeming process.
  • the ceramic support element reduces heat losses from the pouring tube during metal teeming thereby minimising the differential thermal stresses experienced by the pouring tube which lead to propagation of stress microcrack features.
  • the pouring tube is mounted beneath the orifice of a vessel (not shown). Molten metal is poured through the pouring tube for example into a water-cooled mould (not shown). During the metal casting process, the external temperature of the pouring tube rises typically to between 700°C and 900°C. At temperatures up to about 700°C, the pyroplastic interface zone (13; 24) between the pouring tube element (10; 20) and the ceramic element (12; 22) encapsulated in the metallic can remains solid and provides structural continuity and additional mechanical support to the pouring tube. Thereby, structural integrity of the refractory device is provided for e.g. during handling for transport purposes, and initially during assembly into a pouring mechanism and pre-heat.
  • the pyroplastic interface zone becomes deformable, thereby minimising differential thermal stresses experienced by the pouring tube in the region supported by the metallic can. Therefore, in this way the possibility of micro-crack fracture through the refractory device and failure thereof is obviated or mitigated.
  • the present invention results in an improved refractory device that has better reliability and is less prone to damage from differential stress micro-crack features.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Compositions Of Oxide Ceramics (AREA)
  • Continuous Casting (AREA)
  • Ceramic Products (AREA)
  • Furnace Charging Or Discharging (AREA)
  • Casting Support Devices, Ladles, And Melt Control Thereby (AREA)

Claims (9)

  1. Feuerfeste Einrichtung zum Gießen einer Metallschmelze, mit einem rohrförmigen keramischen Gießelement 10, welches in einer metallischen Aufnahme 11 gehalten wird, in der ein keramisches Trägerelement 12 eingeschlossen ist, und einer schockabsorbierenden Zwischenzone 13 zwischen der metallischen Aufnahme 11 und dem rohrförmigen keramischen Gießelement 10, wobei in dieser Zone ein Material vorgesehen ist, dessen thermische Eigenschaften so sind, dass es bei Umgebungstemperatur im Wesentlichen fest ist aber bei erhöhten Temperaturen wie sie beim Metallguß auftreten, deformierbar wird.
  2. Feuerfeste Einrichtung nach Anspruch 1, bei der das Material, welches zur Verwendung in der Zwischenzone 13 ausgewählt wurde, bei Temperaturen bis etwa 700 °C strukturell fest ist und ohne wesentliche chemische Zersetzung bei Temperaturen oberhalb etwa 700 °C deformierbar wird.
  3. Feuerfeste Einrichtung nach Anspruch 1 oder 2, bei der das Material, welches die Zwischenzone 13 bildet, ein pyroplastisches keramisches Material umfaßt.
  4. Keramische Einrichtung nach Anspruch 1, bei der die Zwischenzone 13 ein keramisches Material wie eine Paste oder ein Bindemittel oder ein zusätzliches strukturelles keramisches Element umfaßt.
  5. Feuerfeste Einrichtung nach Anspruch 3, bei der das pyroplastische Material eine sinterbare Zusammensetzung ist, die über wenigstens eine der korrespondierenden Oberflächen von rohrförmigem Gießelement und metallischer Aufnahme aufgebracht ist.
  6. Feuerfeste Einrichtung nach einem der vorhergehenden Ansprüche, bei der das keramische Trägerelement 12 vollständig innerhalb der metallischen Aufnahme 11 eingeschlossen ist und mit und um den oberen Teil des rohrförmigen Gießelementes durch das genannte keramische Trägerelement 12 angepaßt ist, welches ein inneres Profil aufweist, welches im Wesentlichen dem äußeren Profil des Gießrohres entspricht.
  7. Feuerfeste Einrichtung nach Anspruch 6, bei der die wechselseitigen Profile so sind, um korrespondierende Zwischenoberflächen oder andere Paßformen bereitzustellen.
  8. Feuerfeste Einrichtung nach einem der vorhergehenden Ansprüche, wobei das keramische Trägerelement 12 aus einem keramischen Material geringer thermischer Leitfähigkeit vorgeformt ist oder in situ durch Gießen geformt ist.
  9. Feuerfeste Einrichtung nach einem der vorhergehenden Ansprüche, wobei die feuerfeste Einrichtung so bearbeitet ist, dass sie dem beanspruchten Zweck genügt.
EP99963335A 1998-11-27 1999-11-26 Verbesserungen an oder in bezug auf feuerfestprodukte Expired - Lifetime EP1133373B1 (de)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB9825986 1998-11-27
GBGB9825986.4A GB9825986D0 (en) 1998-11-27 1998-11-27 Improvements in or relating to refractory products
PCT/EP1999/009194 WO2000032337A1 (en) 1998-11-27 1999-11-26 Improvements in or relating to refractory products

Publications (2)

Publication Number Publication Date
EP1133373A1 EP1133373A1 (de) 2001-09-19
EP1133373B1 true EP1133373B1 (de) 2002-07-03

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Application Number Title Priority Date Filing Date
EP99963335A Expired - Lifetime EP1133373B1 (de) 1998-11-27 1999-11-26 Verbesserungen an oder in bezug auf feuerfestprodukte

Country Status (7)

Country Link
EP (1) EP1133373B1 (de)
AU (1) AU1967800A (de)
CA (1) CA2352299C (de)
DE (1) DE69902054T2 (de)
ES (1) ES2179694T3 (de)
GB (2) GB9825986D0 (de)
WO (1) WO2000032337A1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1590114B2 (de) † 2003-01-20 2011-10-26 Vesuvius Group S.A Giessdüse, drückvorrichtung für eine giessdüse und giessanlage
WO2014042611A1 (en) 2012-09-11 2014-03-20 Refractory Intellectual Property Gmbh & Co. Kg Refractory pouring device

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2697023T3 (es) 2010-03-30 2019-01-21 Akechi Ceram Co Ltd Buza de colada

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3401024C2 (de) * 1984-01-13 1986-01-16 Fried. Krupp Gmbh, 4300 Essen Aus mehreren Längsabschnitten bestehende Gießdüse zum Zuführen von Metallschmelze in eine Stranggießkokille und Verfahren zur Herstellung des Mundstücks einer derartigen Gießdüse
GB8704764D0 (en) * 1987-02-28 1987-04-01 Thor Ceramics Ltd Tubular refractory product
GB8705224D0 (en) * 1987-03-06 1987-04-08 Thor Ceramics Ltd Refractory assemblies
US5866022A (en) * 1997-03-24 1999-02-02 North American Refractories Company Refractory pour tube with cast plate

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1590114B2 (de) † 2003-01-20 2011-10-26 Vesuvius Group S.A Giessdüse, drückvorrichtung für eine giessdüse und giessanlage
WO2014042611A1 (en) 2012-09-11 2014-03-20 Refractory Intellectual Property Gmbh & Co. Kg Refractory pouring device

Also Published As

Publication number Publication date
ES2179694T3 (es) 2003-01-16
CA2352299C (en) 2009-09-15
AU1967800A (en) 2000-06-19
EP1133373A1 (de) 2001-09-19
WO2000032337A1 (en) 2000-06-08
DE69902054T2 (de) 2003-02-27
CA2352299A1 (en) 2000-06-08
GB9927467D0 (en) 2000-01-19
DE69902054D1 (de) 2002-08-08
GB9825986D0 (en) 1999-01-20

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