EP1133373A1 - Improvements in or relating to refractory products - Google Patents
Improvements in or relating to refractory productsInfo
- Publication number
- EP1133373A1 EP1133373A1 EP99963335A EP99963335A EP1133373A1 EP 1133373 A1 EP1133373 A1 EP 1133373A1 EP 99963335 A EP99963335 A EP 99963335A EP 99963335 A EP99963335 A EP 99963335A EP 1133373 A1 EP1133373 A1 EP 1133373A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- ceramic
- refractory device
- support element
- refractory
- pouring tube
- 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.)
- Granted
Links
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-0 346 378 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.
- 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:
- 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 body having a ceramic pouring tube element and a ceramic support element, said support element being adapted to be received within a metallic can, and there is provided between said elements a shock- absorbing interface zone wherein 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-hat 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 ceramic support element.
- 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.
- Figure 1 is a cross-sectional view of a two-part plate and tube configuration in accordance with prior art
- Figure 2 is a cross-sectional view of a prior art monotube configuration
- Figure 3 is a cross-sectional view of a monotube configuration showing a stress micro-crack fracture of the type minimised by the present invention
- Figure 4 is a section of modified version of monotube assembly as per US 5 866 022.
- Figure 5 is a diagram showing crack mark observed during service trials of such a configuration.
- Figure 6 is a cross-sectional view of a refractory device according to one aspect of the present invention.
- Figure 7 is a cross-sectional view of a refractory device according to a second aspect of the present invention.
- 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 pou ⁇ ng tube element, by virtue of said ceramic support element having an internal profile corresponding sufficiently to the external profile of the pou ⁇ ng tube.
- a stepped shoulder, interference fit arrangement is illustrated.
- the low thermal conductivity of the ceramic support element reduces heat losses from the pou ⁇ ng tube du ⁇ ng metal teeming thereby minimising the differential thermal stresses expe ⁇ enced by the pou ⁇ ng 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 pou ⁇ ng 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 pou ⁇ ng tube du ⁇ ng preheating operations and manipulation.
- the cement has a degree of pyroplas ⁇ city at elevated temperatures encountered du ⁇ ng use of the pou ⁇ ng tube in the metal teeming process to absorb any residual differential stresses, which may be created du ⁇ ng this process.
- the pyroplastic ceramic cement may be formed from an alumina-s ilicate mixture with an addition of fluxing a ⁇ er s to generate the pyroplastic behaviour .
- a typical ana l ys is o f sa id pyroplas tic cement being alumina 20% , s il ica 54 ° , potas s ium oxide 6° , boric oxide 12% and sodium oxide 8 % .
- Such a composi tion wil l provide for progress ive melting from about 700 °C to impart plasticity to the layer .
- Figure 7 illustrates a further embodiment of the present invention wherein t he pounng tube element 20 is coated with a pyroplastic surface layer 24 on i t s upper region to provide the desired low temperature ⁇ gidity and high temperature malleability.
- the coated tube is then encapsulated wi t hin the metallic can by a ceramic concrete 22, which provides mechanical suppor t to t he pou ⁇ ng tube du ⁇ ng the teeming process.
- the ceramic suppor t element reduces heat losses from the pou ⁇ ng tube du ⁇ ng me t al t eeming thereby minimising the differential thermal stresses experienced by the pou ⁇ ng tube which lead to propagation of stress micro- crack features
- the pou ⁇ ng t ube is moun t ed beneath the onfice of a vessel (not shown).
- Molten metal is poured through the pouring tube for example into a water-cooled mould (not shown)
- the external temperature of the pou ⁇ ng tube rises typically to between 700°C and 900°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.
- 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.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
- Compositions Of Oxide Ceramics (AREA)
- Continuous Casting (AREA)
- Furnace Charging Or Discharging (AREA)
- Ceramic Products (AREA)
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GBGB9825986.4A GB9825986D0 (en) | 1998-11-27 | 1998-11-27 | Improvements in or relating to refractory products |
GB9825986 | 1998-11-27 | ||
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 true EP1133373A1 (en) | 2001-09-19 |
EP1133373B1 EP1133373B1 (en) | 2002-07-03 |
Family
ID=10843138
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP99963335A Expired - Lifetime EP1133373B1 (en) | 1998-11-27 | 1999-11-26 | Improvements in or relating to refractory products |
Country Status (7)
Country | Link |
---|---|
EP (1) | EP1133373B1 (en) |
AU (1) | AU1967800A (en) |
CA (1) | CA2352299C (en) |
DE (1) | DE69902054T2 (en) |
ES (1) | ES2179694T3 (en) |
GB (2) | GB9825986D0 (en) |
WO (1) | WO2000032337A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8127972B2 (en) | 2003-01-20 | 2012-03-06 | Vesuvius Crucible Company | Pouring nozzle, pushing device for a pouring nozzle and casting installation |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
ES2697023T3 (en) | 2010-03-30 | 2019-01-21 | Akechi Ceram Co Ltd | Casting buza |
EP2895286A1 (en) | 2012-09-11 | 2015-07-22 | Refractory Intellectual Property GmbH & Co. KG | Refractory pouring device |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3401024C2 (en) * | 1984-01-13 | 1986-01-16 | Fried. Krupp Gmbh, 4300 Essen | Casting nozzle consisting of several longitudinal sections for feeding molten metal into a continuous casting mold and method for producing the mouthpiece of such a casting nozzle |
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 |
-
1998
- 1998-11-27 GB GBGB9825986.4A patent/GB9825986D0/en not_active Ceased
-
1999
- 1999-11-22 GB GBGB9927467.2A patent/GB9927467D0/en not_active Ceased
- 1999-11-26 DE DE69902054T patent/DE69902054T2/en not_active Expired - Lifetime
- 1999-11-26 WO PCT/EP1999/009194 patent/WO2000032337A1/en active IP Right Grant
- 1999-11-26 ES ES99963335T patent/ES2179694T3/en not_active Expired - Lifetime
- 1999-11-26 EP EP99963335A patent/EP1133373B1/en not_active Expired - Lifetime
- 1999-11-26 CA CA002352299A patent/CA2352299C/en not_active Expired - Fee Related
- 1999-11-26 AU AU19678/00A patent/AU1967800A/en not_active Abandoned
Non-Patent Citations (1)
Title |
---|
See references of WO0032337A1 * |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8127972B2 (en) | 2003-01-20 | 2012-03-06 | Vesuvius Crucible Company | Pouring nozzle, pushing device for a pouring nozzle and casting installation |
Also Published As
Publication number | Publication date |
---|---|
CA2352299C (en) | 2009-09-15 |
WO2000032337A1 (en) | 2000-06-08 |
CA2352299A1 (en) | 2000-06-08 |
GB9825986D0 (en) | 1999-01-20 |
ES2179694T3 (en) | 2003-01-16 |
GB9927467D0 (en) | 2000-01-19 |
DE69902054T2 (en) | 2003-02-27 |
EP1133373B1 (en) | 2002-07-03 |
AU1967800A (en) | 2000-06-19 |
DE69902054D1 (en) | 2002-08-08 |
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