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WO1990008611A1 - Rotor - Google Patents

Rotor Download PDF

Info

Publication number
WO1990008611A1
WO1990008611A1 PCT/GB1990/000112 GB9000112W WO9008611A1 WO 1990008611 A1 WO1990008611 A1 WO 1990008611A1 GB 9000112 W GB9000112 W GB 9000112W WO 9008611 A1 WO9008611 A1 WO 9008611A1
Authority
WO
WIPO (PCT)
Prior art keywords
rotor
coupler
rotor stem
stem
pressed
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.)
Ceased
Application number
PCT/GB1990/000112
Other languages
English (en)
Inventor
Stephen John Lee
James Frederick Houghton
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.)
Thor Ceramics Ltd
Original Assignee
Thor Ceramics Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Thor Ceramics Ltd filed Critical Thor Ceramics Ltd
Publication of WO1990008611A1 publication Critical patent/WO1990008611A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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
    • 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
    • B22D41/186—Stopper-rods therefor with means for injecting a fluid into the melt

Definitions

  • This invention relates to a rotor stem forming part of a rotary valve assembly for use with apparatus for handling of molten material, especially metal.
  • the invention is particularly useful in apparatus for controlling the pouring of melt from a tundish into a mould such as in the production of ingots or in the continuous casting of steel for example.
  • Rotary valve assemblies of a known type comprise a replaceable outlet component locatable in the base of a vessel such as a tundish and having a throughbore to act as an outlet passage from the interior of the vessel to the exterior, with a cooperating rotatable closure component of generally columnar shape having an end surface adapted to bear upon a surface of the outlet component and having in that end surface an orifice registrable with the passage, and in its sidewall, an opening communicating with said orifice whereby a melt flow pathway out of the vessel may be formed by appropriate rotational control of the closure component.
  • These components may be conveniently referred to as "nozzle” and “rotor stem” components respectively.
  • the cooperating surfaces of these components are usually complementary convex/concave surfaces to facilitate location of one surface with respect to the other.
  • the rotor stem will be formed from particulate or granular refractory materials by an isostatic pressing method using arbors and void forming materials with appropriate curing and extensive machine finishing steps to provide a substantially cylindrical body having an axial throughbore and usually non-uniform exterior contour arising from the need to provide generally thicker material at the nozzle contacting end for strength and surfaces for receiving a driving assembly at the opposite end.
  • the rotor stem is installed in a substantially vertical position and a large proportion thereof immersed in molten material at very much higher temperatures than the upper end which is located in a drive assembly.
  • the drive assembly includes components which transmit pressure from an actuator mechanism to the rotor to maintain close mating surface contact with the nozzle component.
  • this invention provides a rotor stem comprising a longitudinal body, formed from refractory materials by an isostatic pressing method, having one end adapted to receive a driving component, wherein said end contains a coupler for attachment of a gas feed pipe which is co-pressed into the body during forming thereof by isostatic pressing.
  • the throughbore present in the rotor of the known type need not be of such large diameter at the driven end of the rotor and may instead be a significantly narrower bore internal channel the length of which is a matter of choice taking into account the amount of material required to form the shape and the strength required of the rotor.
  • the manner of forming such a channel can be by use of void formers or similar means as is already known in the art.
  • the rotor stem head is substantially solid in comparison with the known assembly.
  • the driven end of the rotor stem may be formed by moulding and machining to have a polygonal shape suitable for receiving a corresponding drive cap forming part of a driving mechanism for turning the rotor.
  • the coupler may be of thin metal, preferably the thinnest capable of fulfilling its intended purpose in order to minimise differential thermal expansion problems, and has a shape which resists rotation during assembly to facilitate insertion of the gas pipe and resist loosening of the coupling during use of the rotor.
  • the coupler may comprise a female threaded barrel portion having an external surface which is adapted to resist rotation by being non-circular, having flats, or having projections or recesses which will provide an interference fit with the surrounding refractory material in the pressed product.
  • the coupler will have a surface coating such as boro-silicate glass or the like to provide a bond between the refractory material of the rotor stem and the coupler.
  • the coupler geometry enables it to be incorporated readily in the tooling set up for pressing of the rotor body and the surface treatment of the coupler with a bonding agent ensures total adhesion and seal integrity between the coupler and the body of the rotor stem. This enables the problems associated with the prior art separate forming of vented plug insert and post-pressing assembly of the rotor stem head, with attendant gas leakage risks in such a multi-part head to be avoided.
  • the coupler may alternatively be pre-for ed from a durable high strength ceramic material to provide a suitably shaped insert having an internal threaded socket for receiving a gas pipe, which insert by its nature would be readily compatible with the refractory material used in pressing the rotor stem, allowing it to be co-pressed into the body of the rotor stem to provide a head design which would also avoid the stress raisers evident in the known design as discussed above.
  • a suitable ceramic material would be reaction bonded silicon nitride.
  • a further way of avoiding use of the separately formed vented plug arrangement involves formation of a compression joint between a gas pipe and the rotor stem body which is adapted according to the invention to receive the pipe by pressing of a blend of refractory materials in a region of the driven end of the rotor stem to form in that end a tapered opening having durable surfaces for engaging the gas pipe in a close fit arrangement, which engagement is ensured by providing a threaded portion on the exterior of the gas pipe and a corresponding thread on a cap component which is fastenable to said end of the rotor stem.
  • Fig. 1 is a longitudinal section through a rotor stem of the known type illustrating the cemented plug and pipe arrangement which can prove problematic in use
  • Fig. 2 is a longitudinal section through a rotor stem according to the invention illustrating the increased end section thickness which incorporates an integral fully sealed gas coupler fitment
  • Fig. 3 is an enlarged view, in section, of the end of the rotor shown in Fig. 2 illustrating one embodiment of the coupler according to this invention.
  • Fig. 4 is a view in section of the end of a rotor stem in accordance with this invention wherein a compression fitting of the gas feed pipe is provided.
  • a rotor stem is formed by isostatic pressing from particulate refractory materials, e.g. graphitised alumina, to provide an elongate body 1 of generally columnar shape having an axial throughbore 2.
  • the body 1 has a thickened end 3 with a concave surface 4 which, in use, bears upon a corresponding convex surface of a nozzle component (not shown) fixed in the base of a vessel (not shown) containing molten material.
  • This thickened end has an eccentric orifice 5 in the nozzle- contacting surface 4 which is registrable with an outlet passage in the nozzle.
  • a melt flow pathway out of the vessel may be formed by controlled rotation of the rotor stem about its longitudinal axis to bring the orifice 5 into register with the passageway.
  • Rotation of the rotor stem causes displacement of the orifice 5 so that it no longer corresponds with the passage which of course cuts off melt flow from the vessel.
  • Such rotation of the rotor stem is accomplished by means of a drive mechanism including a drive cap 9 attachable, conveniently by a simple press fit, to the other end 10 of the rotor stem which is generally thinner than the nozzle-contacting end and machined to fit into the drive mechanism.
  • the throughbore 2 is plugged at the nozzle- contacting end 3 by a vented plug 7 and at the other end 10 by a vented plug assembly 8 including a gas supply pipe 11. These plugs are inserted after pressing of the rotor stem body and cemented into position. Since the plug 8 is a separately pressed article made up of a threaded pipe coupling 12, voiding materials and refractory materials it is of relatively large size to provide strength, this requires the throughbore to be of relatively large diameter. The outer diameter of the rotor stem is constrained by the need to fit the drive assembly. This means that the body thickness at the driven end 10 may represent a source of weakness which could result in reduced operational life due to mechanical strength failure.
  • the nozzle contacting end 13 of the rotor stem can be equivalent to that of the prior art.
  • the driven end 30 is modified to provide, in a single forming step by isostatic pressing, an integral coupling 32 for a gas pipe 31 as is more clearly shown in Fig. 3.
  • the rotor stem according to this embodiment of the invention is formed by isostatic pressing from particulate refractory materials to provide an elongate body 21 of generally columnar shape having an internal gas duct 22 extending longitudinally from a thickened end 13 which has a concave surface 14 for a known purpose as indicated above with a corresponding convex surface of a nozzle component (not shown) fixed in the base of a vessel (not shown) containing molten material.
  • this thickened end has an eccentric orifice 15 in the nozzle- contacting surface 14 which is registrable with an outlet passage in the nozzle and, in its sidewall, an opening 16 communicating with the orifice 15 to define, in conjunction with the passage in the nozzle, a melt flow pathway out of the vessel when the orifice 15 is aligned with the passageway.
  • rotational control over the rotor stem is accomplished by means of a drive mechanism including a drive cap 19 attachable by pressing onto the other end 30 of the rotor stem which is substantially solid and formed to fit into the drive mechanism.
  • This end 30 is formed from refractory materials in which there is located a void former to provide a narrow bore channel 18 linking a gas supply pipe 31 with the gas duct 22.
  • the gas duct 22 has a vented plug 17 and at its other end whereby controlled supply of inert gas may be passed directly through the rotor stem in a manner generally known per se.
  • the modified rotor stem according to this invention provides a more efficient way of handling the gas due to elimination of all joints evident in previous systems apart from that between the gas pipe and the coupler.
  • the superior mechanical strength provided by the very much thicker upper end 30 provides increased operational life. Further improvements in resistance to impact damage and thermal shock are obtained by use of a smaller diameter gas duct 22 which is accompanied by a corresponding thickness in the body around it.
  • the duct 22 need not extend so far through the body 21 as shown in the drawing and may only be a small chamber in a lower portion of the rotor stem in which case the channel 18 will be of greater length. This is possible because there is no need to provide a large access aperture for receiving a vented plug and coupler assembly as in the prior art.
  • an improved rotor stem which is otherwise similar to that shown in Fig. 2 has an upper end 40 including an integral vented coupler 42 formed from refractory material, preferably zirconia/alumina or reaction bonded silicon nitride or the like, which has a surface 44 adapted to receive a tapered end 43 of a gas supply pipe 41 in a close fit under compression.
  • the upper end 40 is also shaped to receive a drive cap 39 in the crown of which there is a tapped bore 29 through which said tapered end 43 may pass to engage said surface 44.
  • the gas supply pipe has a threaded exterior surface portion 45 for locating the pipe in the drive cap ,29 which once fixed to the rotor stem head for use forces the gas pipe 41 into engagement with the coupler surface 44 to provide a compression seal.
  • a narrow bore gas channel 38 is used to convey gas from the coupler 42 through the rotor stem body which may then be substantially thicker in that region to improve mechanical strength.
  • Such an arrangement has advantages in simplicity of manufacture, reduction of the number of joints to a single metal-ceramic joint which is self closing due to the normal bearing loads on the drive cap which are required to provide good stem to nozzle contact also acting to maintain close fit between the metal pipe and ceramic coupler surface.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Ceramic Products (AREA)
  • Casting Support Devices, Ladles, And Melt Control Thereby (AREA)

Abstract

Une tige de rotor faisant partie d'un ensemble de vanne rotative utilisée avec un appareil de manipulation de matière fondue, notamment du métal, comprend un corps longitudinal (21), réalisé à partir de matériaux réfractaires selon un procédé de pression isostatique, comportant une extrémité (30, 40) adaptée pour recevoir un élément d'entraînement. Ladite extrémité contient, afin de permettre le raccordement d'un tube (31, 41) d'alimentation en gaz inerte, un raccord (32, 42) co-pressé dans ledit corps pendant sa formation par pression isostatique, et fait de métal mince ou de matière céramique hautement résistante, afin de permettre la fixation directe dudit tube d'alimentation par connexion filetée ou raccordement par compression à une tête de rotor solide.
PCT/GB1990/000112 1989-01-26 1990-01-26 Rotor Ceased WO1990008611A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8901683.6 1989-01-26
GB8901683A GB2228222A (en) 1989-01-26 1989-01-26 Rotor for molten material discharge control valve

Publications (1)

Publication Number Publication Date
WO1990008611A1 true WO1990008611A1 (fr) 1990-08-09

Family

ID=10650621

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1990/000112 Ceased WO1990008611A1 (fr) 1989-01-26 1990-01-26 Rotor

Country Status (4)

Country Link
CA (1) CA2008742A1 (fr)
GB (1) GB2228222A (fr)
WO (1) WO1990008611A1 (fr)
ZA (1) ZA90583B (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996016757A1 (fr) * 1994-11-29 1996-06-06 Didier-Werke Ag Organe de fermeture et/ou de reglage pour un recipient metallurgique
WO1999062659A1 (fr) * 1998-05-29 1999-12-09 Didier-Werke Ag Bouchon pour fermer des cuves contenant des metaux en fusion

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2120369A (en) * 1982-05-20 1983-11-30 Ksr Int Ltd An improved metallurgical lance
EP0196847A2 (fr) * 1985-03-26 1986-10-08 British Steel plc Vannes d'arrêt pour récipients contenant un matériau liquide
DE3511772A1 (de) * 1985-03-30 1986-10-09 Didier-Werke Ag, 6200 Wiesbaden Blaslanze
GB2210305A (en) * 1987-10-02 1989-06-07 Thor Ceramics Ltd Refractory monoblock stopper
EP0358535B1 (fr) * 1988-12-29 1992-05-06 Vesuvius France S.A. Quenouille monobloc

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2120369A (en) * 1982-05-20 1983-11-30 Ksr Int Ltd An improved metallurgical lance
EP0196847A2 (fr) * 1985-03-26 1986-10-08 British Steel plc Vannes d'arrêt pour récipients contenant un matériau liquide
DE3511772A1 (de) * 1985-03-30 1986-10-09 Didier-Werke Ag, 6200 Wiesbaden Blaslanze
GB2210305A (en) * 1987-10-02 1989-06-07 Thor Ceramics Ltd Refractory monoblock stopper
EP0358535B1 (fr) * 1988-12-29 1992-05-06 Vesuvius France S.A. Quenouille monobloc

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996016757A1 (fr) * 1994-11-29 1996-06-06 Didier-Werke Ag Organe de fermeture et/ou de reglage pour un recipient metallurgique
WO1999062659A1 (fr) * 1998-05-29 1999-12-09 Didier-Werke Ag Bouchon pour fermer des cuves contenant des metaux en fusion
EP1177845A1 (fr) * 1998-05-29 2002-02-06 Didier-Werke Ag Bouchon pour fermer des cuves contenant des metaux en fusion

Also Published As

Publication number Publication date
GB8901683D0 (en) 1989-03-15
ZA90583B (en) 1990-10-31
GB2228222A (en) 1990-08-22
CA2008742A1 (fr) 1990-07-26

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