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
  • B22D41/16—Closures stopper-rod type, i.e. a stopper-rod being positioned downwardly through the vessel and the metal therein, for selective registry with the pouring opening
  • B22D41/18—Stopper-rods therefor

Definitions

• the invention relates to an elongated stopper device for flow control of molten metal, i.e. for controlling the flow of molten metal from a metallurgical vessel, such as a tundish.
• stopper rods have also been used to introduce an inert gas, such as argon, into the molten steel for removing non-metallic inclusions from the molten metal.
• an inert gas such as argon
• stopper device In all cases the stopper device must withstand hours submerged in molten metal. It must also be capable of enduring the harsh thermal shock encountered on the start-up of casting and any mechanical forces imposed to it. Insofar many attempts have been made to improve the mechanical and thermal properties of such a stopper device and to improve its behaviour during use.
• EP 0 358 535 B2 discloses a one-piece refractory stopper rod adapted to a lifting mechanism, comprising an elongated stopper rod body of a refractory material, which body being provided with a bore hole, having a longitudinal axis and extending from an upper surface of said body downwardly. Within said axial bore hole a metal bushing is inserted to threadably receive a threaded part of a metal rod, inserted in said refractory body for attachment to a corresponding lifting mechanism.
• a stopper device providing an upper part of the bore hole embodying a ceramic insert.
• This insert provides an inner thread, corresponding to an outer thread of a corresponding metal rod threadably fixed within said insert after insertion of the rod into said threaded insert. Whilst the use of two ceramic materials reduces the risk of differential stresses between the body material and the holding insert problems remain associated with the difficulty in maintaining an accurate threadform in a high strength ceramic material at an acceptable cost.
• the invention provides a fixing means arranged predominantly perpendicular to the longitudinal axis of said body and/or said bore hole respectively and at a specific position along the length of the bore within said body.
• these fixing means are much smaller than a bushing, i.e. much less different material is introduced into the ceramic body and much less thermal and mechanical stresses between fixing means (anchor) and ceramic body are to be expected.
• the said anchor is arranged at a specific height of said elongated stopper device at a distance to its upper surface and at a distance to its lower end. Typically it is arranged at a place between 10 and 40 % of the total length of the stopper device, calculated from the upper end of the refractory body, which may be 5-25 cm, typically about 10 cm from the upper end.
• a generally radial fixing means presents a significantly reduced axial length than any insert or bushing extending along the longitudinal axis of a stopper. Any mechanical stresses generated in the ceramic body by the longitudinal thermal expansion effects arising from said generally radial fixing means are therefore much lower than those generated with prior art constructions. Further it may easily be fixed within the ceramic refractory surroundings (refractory body material), for example during isostatic pressing of said stopper device.
• the manufacturing may be done as follows: The aforementioned anchor(s), for example sheet like part(s) is (are) placed with their end portion located into corresponding slits of a suitable mandrel (core rod). A rubber outer mould is placed over the mandrel assembly and a refractory ceramic material is filled into the cylindrical space between the mandrel and mould. Thereafter the mould containing the refractory material, including the fixing means, is isostatically pressed.
• the outer mould is then removed and the mandrel, made of at least two longitudinally running parts, is removed from the compacted product leaving the outer portion(s) of the anchor(s) (sheet like parts) firmly embedded in the ceramic body with their inner extremity(ies) projecting into predetermined position(s) within the ceramic bore.
• a sealing member may further be placed within said mould, as will be described later.
• the invention relates to an elongated stopper device for flow-control of molten metal from a vessel, containing molten metal, said device comprising:
• said bore hole being equipped along its length with at least one anchor of a different material, fixed within said body between the upper surface of said body and a lower end of said bore hole and proj ection radially into said bore hole with its main surfaces running predominantly perpendicular to the longitudinal axis of the bore hole,
• said anchor being adapted to receive and fix one threaded end of a metal rod, inserted into said bore hole.
• said metal rod has an at least partially threaded section at its inserted end. This threaded section serves, together with the anchor (fixing means) for attachment of said metal rod within said bore hole of said refractory body.
• this fixing (anchoring) means should best have a certain circumferential length. It may extend over 20 to ⁇ 360° of the inner wall of said bore hole or even a bit more.
• said sheet like part with a certain declination (descending gradient or slope) with respect to the longitudinal axis of the bore hole, but not necessary to achieve the desired locking.
• the anchor (sheet like part) is more or less ring shaped, i.e. running in the circumferential direction around the inner bore hole surface for more than 180°, especially more than 270°C and it must be sloped when this part has a length of more than 360°.
• a snap ring design is one further possibility.
• said anchor may be designed as a ring, for example with a circumferen ⁇ tial length between 270° and ⁇ 360° or up to 450° or 300° to 400° it is also possible to prepare said fixing means by at least two anchors, each designed like a ring section and arranged at a distance to each other along an imaginary helical line.
• a further embodiment provides fixing means made of three anchors, each designed like a ring section and arranged at equal distances to each other along an imaginary helical line. Even two or three radially arranged pins, spaced to each other, may provide the necessary anchoring means for securing and holding the rod within the body.
• the anchor(s) may also be arranged along a plane, perpendicular to the longitudinal axis of the rod. It becomes clear from the explanation above that a one piece fixing means is the most convenient way for an easy production of said stopper device.
• Said fixing means may be made of any material, different from the material of the refractory body and strong enough to threadably receive the threaded part of the corresponding metal rod.
• the fixing means may be made of metal or special ceramics like silicon nitride, zirconia or alumina.
• a sealing member may be arranged along said bore hole and best adjacent to said fixing means.
• a corresponding sealing member may be placed upon a corresponding annular sealing surface, provided at a certain height of the bore hole.
• Said sealing means may also be arranged along a circumferential wall of said bore hole below or above said fixing part and extending radially into said bore hole and longitudinally along a certain length of said bore hole and adapted to receive said rod in a threadably manner.
• Said sealing member may have a cylindrical shape. It should protrude into the bore hole.
• That part of the bore hole, receiving the sealing member may be conically designed with its smaller part at its lower end.
• the rod may then have a smaller width at its part adjacent to said sealing member compared with its part on top.
• the sealing member may be made of any material withstanding high temperatures as may be present during use of stopper device.
• Graphite is one of those materials.
• a possible material is a compressed graphite material with a purity > 95 weight-% carbon and a density of approximately 1,4 g/cm 3 .
• the seal may have the form of a preformed component which can be either inserted into the stopper body immediately prior to the installation of the steel support rod or co-formed with the ceramic body of the stopper rod during the production process.
• the seal may be created during the fabrication process of the stopper by compression of a graphite element comprising either exfoliated graphite powder or a coil of a graphite foil, placed around the forming tool (mould) and then surrounded by the ceramic body material of the stopper during the mould filling process.
• a graphite element comprising either exfoliated graphite powder or a coil of a graphite foil
• the corresponding rod will be equipped with an axial bore through which the gas is fed.
• the corresponding bore hole of the body will then be provided with at least one opening at its lower end.
• the stopper device comprises an elongated refractory body 10 with a central bore hole 12, positioned coaxially with respect to body 10 and adapted to receive fixedly a metal rod 14 for its attachment to a (non-shown) lifting mechanism.
• the bore hole 12 is of more or less cylindrical shape and is running from an upper surface 1 Ou of the body 10 downwardly (arrow D) and terminating in a (non-shown) opening at a lower end of said body 10.
• a sheet like metal ring 16 is integrated in the refractory material of body 10. Said ring projects radially into said bore hole 12. Main surfaces (upper surface 16u; lower surface 161) are running predominantly perpendicular to a longitudinal axis A of said bore hole 12.
• said flat ring 16 is arranged such that is provides an angle ⁇ of ca. 3 degrees to a horizontal plane (perpendicular to longitudinal axis A). This angle may be adapted to match the pitch of the threadform on the metal rod 14. Said ring 16 is not closed but slit and encircles an angle of about 330°. Free ends of said ring are offset in the longitudinal direction of bore hole 12.
• This sheet like ring 16 serving as a fixing means for said rod 14, which will be described later, has been co-pressed with body 10. It protrudes (projects) into bore hole 12 over a certain width so as to threadably receive an outer thread 14t (symbolized by dots) of a lower part 141 of metal rod 14, which may have a central, longitudinal through passage 14c (symbolized by lines).
• Rod 14 is then further introduced into bore hole 12 (downwardly, arrow D) and then engages a cylindrical graphite gasket 18, arranged over a length L in front of an inner wall 12w of bore hole 12.
• a cylindrical graphite gasket 18 arranged over a length L in front of an inner wall 12w of bore hole 12.
• the gasket material penetrates into spaces of thread 14t, thereby providing intimate sealing between body 10 and rod 14 all over length L.
• the final position of rod 14 within bore hole 12 is characterized by a small projection of threaded end 14e past the end of sealing member 18.
• the threaded rod could finish within the length of the sealing element.
• Blocking means 20, 22 have a nut-like shape and are prepared with inner threads, corresponding to thread 14t of rod 14.
• the described design leads to an improved stopper device which may be used for different purposes, i.a. for feeding a gas along channel 14c and bore hole 12 into a metal melt.
• the intimate contact between gasket 18 and outer thread 14t of rod 14 are further responsible for the radial compression of the sealing element and improved tightness of said device.
• the expansion of the metallic rod at service temperature serves to further increase the sealing efficiency by maintaining compressive forces on the seal.
• the fixing means In the longitudinal direction the fixing means should be as small as possible. It may have a "thickness" of ⁇ 5mm, ⁇ 3mm, ⁇ 2mm or even ⁇ lmm, while the "length" (L) of said sealing means may be > 10 mm, > 20mm, > 30mm or > 40 mm.
• the invention includes embodiments with two or more fixing means at different positions along the longitudinal axis of the elongated stopper rod, i.e. the respective fixing means have a distance to each other (in the longitudinal direction of the bore hole). The distance may be in the range of a few cm or more. These distinct fixing means may coact with one or more outer threads of the metallic rod.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
• Vehicle Body Suspensions (AREA)
• Spinning Or Twisting Of Yarns (AREA)
• Special Conveying (AREA)
• Continuous Casting (AREA)
• Fishing Rods (AREA)
• Control Of Throttle Valves Provided In The Intake System Or In The Exhaust System (AREA)
• Dowels (AREA)
• Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (13)

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Citations (9)

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• 2004
  • 2004-07-29 ES ES04017978T patent/ES2268551T3/es active Active
  • 2004-07-29 DE DE602004001686T patent/DE602004001686T2/de not_active Expired - Fee Related
  • 2004-07-29 PL PL04017978T patent/PL1621270T3/pl unknown
  • 2004-07-29 EP EP04017978A patent/EP1621270B1/en not_active Expired - Fee Related
  • 2004-07-29 AT AT04017978T patent/ATE333957T1/de not_active IP Right Cessation
• 2005
  • 2005-07-09 MX MXPA06014280A patent/MXPA06014280A/es active IP Right Grant
  • 2005-07-09 BR BRPI0507548-3A patent/BRPI0507548A/pt not_active IP Right Cessation
  • 2005-07-09 RU RU2006126990/02A patent/RU2338626C2/ru not_active IP Right Cessation
  • 2005-07-09 US US10/597,076 patent/US20070138715A1/en not_active Abandoned
  • 2005-07-09 WO PCT/EP2005/007470 patent/WO2006012975A1/en active Application Filing
  • 2005-07-09 CN CNB2005800034172A patent/CN100384570C/zh not_active Expired - Fee Related
  • 2005-09-07 UA UAA200611160A patent/UA84324C2/ru unknown
• 2006
  • 2006-12-04 ZA ZA200610112A patent/ZA200610112B/en unknown

Patent Citations (9)

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