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
• • 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 stopper rod for controlling the flow of molten metal, for example from a vessel, such as a tundish, to a mould, and more preferably, to a stopper rod for supplying an inert gas to the melt in the vessel.
• Such a stopper rod is well known, it being moved in the direction of its longitudinal axis by a lifting device external to the vessel in which the stopper rod is disposed, so that an outlet opening in the base of the vessel, into which the stopper rod fits at its lowest position, shutting it off completely, is opened either more or less. The flow of metal through the opening is thus controllable.
• An object of the invention is to provide a stopper rod in an improved form.
• a stopper rod comprising a refractory material stopper rod body having an internal passageway extending from a first end of the body towards a second end thereof, a metal carrier element having one of its ends received in said passageway, the carrier element having a laterally enlarged portion received in a laterally enlarged portion of the passageway, which passageway portion defines a seating surface, and sealing means between said seating surface and an underside of the laterally enlarged portion of the carrier element, wherein an insert is threadedly engaged with one of the carrier element and the stopper rod body at a position above said laterally enlarged portion of the carrier element, with further sealing means being disposed between said insert and the carrier element.
• the carrier element which serves, in use, to connect the stopper rod to a lifting device, has a gas supply passage extending therethrough.
• the sealing means is a graphoil seal.
• the insert is threadedly engaged with the carrier element.
• the further sealing means is a packing gland seal.
• the insert is threadedly engaged with the stopper rod body.
• the further sealing means is a graphoil seal, which is preferably thicker than the graphoil seal forming said sealing means.
• the insert is threadedly engaged with a ceramic insert which is preferably pressed into the stopper rod to form part thereof.
• the sealing means is disposed between complementary frustoconical surfaces respectively of the enlarged portion of the carrier element and said seating surface. Until the stopper rod heats up, the sealing means is compressed between the carrier element and the stopper rod body and provides a gas-tight seal therebetween. As the stopper rod heats up, gas tightness is maintained by the further sealing means, even if the seal provided by the sealing means starts to leak due to the expansion of the metal carrier element.
• the insert is engaged with a complementary thread on the carrier element.
• the insert is screwed down tightly on the further sealing means to effect radial sealing to the inner annular wall of the passageway of the stopper rod body.
• the whole assembly simply slides up fractionally, but the force on the further sealing means, and hence the gas-tightness, is maintained.
• the insert is a collar, which can be metallic or ceramic, threadedly engaged with a corresponding thread at an upper inner surface of the internal passageway in the stopper rod body.
• the thread can be pressed in the stopper rod body passageway, or provided by a pressed-in ceramic insert forming part of the stopper rod body.
• the insert is in the form of a nut screw-threadedly engaged on the carrier element, which nut, when tightened, effects axial compression of said further sealing means, resulting in sealing between the stopper rod body and the carrier element.
• the nut preferably effects axial compression of said further sealing means through the intermediary of a washer.
• the washer is located around the carrier element at one end of the stopper rod body.
• the washer is larger than the further sealing means, and particularly of larger diameter than the diameter of the upper end of the internal passageway in the stopper rod body, in which upper end the further sealing means is received.
• the further sealing means is preferably two graphoil seals which stand proud of said upper end of the stopper rod body when the nut is untightened, and are axially compressed into said upper end of the passageway when the nut is tightened onto the washer to cause the washer axially to compress the graphoil seals.
• Figure 1 is a schematic side view of the interior of the upper end of a prior art stopper rod
• Figure 2 is a view like Figure 1 , for a stopper rod of the invention.
• Figure 3 is a similar view to Figure 2, for a stopper rod according to a further embodiment of the invention.
• Figure 4 is a view like Figure 3 of a stopper rod according to a still further embodiment of the invention.
• Figure 5 is a split schematic cross-sectional view of the upper end of a stopper rod of the invention, the left half showing sealing means uncompressed, and the right half showing the sealing means compressed.
• Figure 1 schematically shows the upper end of a prior art stopper rod 10 having a conventional stopper rod body 11 of refractory/ceramic material.
• a circular cross-section longitudinal bore 12 Extending centrally, axially within the stopper rod body 11 from the upper end thereof is a circular cross-section longitudinal bore 12.
• Extending downwards from this surface 13 is a constant diameter circular cross-section part, which leads to a radially enlarged portion of the bore in which is secured a ceramic insert 14, the insert being secured to the stopper rod body 11. Below this insert 14, the remainder of the bore 12 has the same diameter as the part between the surface 13 and the insert 14.
• the insert could be of metal or of cermet material.
• a metallic carrier rod 15 which at its upper end outside of the bore 12 is fixed in any convenient manner to a lifting device for raising and lowering the stopper rod, in use, in a vessel such as a tundish, in the normal manner.
• the carrier rod 15 is of circular cross-section, but is provided with a laterally (radially) enlarged portion in the form of an annular collar 16, the external shape of which substantially matches the lower end of the bore 12 above the surface 13 together with the surface 13 itself.
• the upper part of the collar is cylindrical, as at 17, whilst the lower part is in the form of a frustoconical surface 18 matching the frustoconical seating surface 13.
• the carrier rod 15 is of its normal circular diameter, but this is provided with an external thread at the position of the insert 14, so that the engagement of the rod 15 with the insert 14 enables a lifting of the carrier rod 15 to be transmitted to the stopper rod body 11 so as to lift or lower the stopper rod 10 in use in the normal manner.
• a graphoil seal 19 there is disposed between the corresponding frustoconical surfaces 13 and 19 a graphoil seal 19.
• a problem with the prior art system shown in Figure 1 is that when the stopper rod becomes heated, in use, the thermal expansion of the carrier rod 15 leads to reduced pressure being applied to the graphoil seal 19, resulting in leakage.
• the embodiment of the present invention shown in Figure 2 is designed to solve that problem. As can be seen from the drawing, all the features of the stopper rod shown in Figure 1 are present in Figure 2 and have accordingly been numbered identically, but with the suffix a.
• the stopper rod shown in Figure 3 comprises a refractory /ceramic stopper rod body l ib with a longitudinal bore 12b extending therethrough from its open upper end.
• This upper laterally (radially) enlarged part of the bore 12b is formed with a seating surface 13b of frustoconical form, and spaced below this surface 13b there is pressed into the material of the body 11 a fixing insert 14b with which an externally threaded end of the metallic carrier rod 15b is engaged so that a lifting or lowering of the carrier rod will result in a corresponding lifting or lowering of the stopper rod in its vessel.
• the carrier rod 15b which is preferably metallic, has a central gas passage 22 extending therethrough. It is provided externally with a collar 16b made up of an upper cylindrical part 17b and a lower part which has a frustoconical undersurface 18b. As with the Figure 2 arrangement, a seal 19b, preferably a graphoil seal, is trapped between the frustoconical surface 18b and the seating surface 13b to provide a gas tight seal when the stopper rod is unheated.
• a seal 19b preferably a graphoil seal
• a screw thread 23 is provided, for example by pressing, into the inner surface of the upper part of the bore 12b and an insert in the form of an annular collar 24 or equivalent is screw-threadedly engaged with the thread 23, there being, as shown, radial clearance between the inner cylindrical surface of the collar and the outer cylindrical surface of the carrier rod 15b.
• This is in contrast to the Figure 2 arrangement, where this radial clearance can be provided between the external surface of the nut 20 and the inner cylindrical surface of the bore in which the nut is received.
• the collar 24 is screwed down onto the seal 25 which is compressed thereby. Accordingly when the stopper rod is unheated, there is sealing both by way of the seal 19b and also by way of the seal 25, both of which seals are under compression. However as the stopper rod is heated, and the carrier rod 15b expands, the seal 19b is likely to start to leak in the normal manner as the compression thereof decreases due to the expansion of the carrier rod 15b. However the upper seal 19b, which is restrained by the fixed screwed-in collar 24, will be subject to additional compressive forces between the expanding carrier rod 15b and the retained collar 24 to provide an effective gas-tight seal.
• Figure 3 shows a conventional washer 26 on the carrier rod 15b at the top of the stopper rod body l ib, this washer being Held down onto the top of the stopper rod body by a nut 27 which is screw threaded onto the carrier rod 15b, the washer and nut providing a conventional lock at the top of the stopper rod body.
• the stopper rod of the invention shown in Figure 5 is similar in several respects to that shown in Figure 3, having a stopper rod body l ie of refractory /ceramic material with a central, longitudinally extending circular cross-section bore 12c, which is open at the end of the stopper rod which is uppermost in use.
• This upper laterally (radially) enlarged part of the bore 12c is formed with a seating surface 13c of frustoconical form, and spaced below this surface there is pressed into the material of the body I le a (ceramic) fixing insert 14c with which an externally threaded end of the preferably metallic carrier element in the form of a rod 15c is engaged, so that a lifting or lowering of the carrier rod will result in a corresponding lifting or lowering of the stopper rod in its vessel.
• the carrier rod 15c has a central gas passageway through it. It has an external collar 16c made up of an upper cylindrical part 17c and a lower part with a frustoconical under surf ace 18c. A seal 19c, preferably a graphoil seal, is trapped between the surface 18c and the seating surface 13c to provide a gas tight seal when the stopper rod is unheated.
• a conventional washer 26c is received on the carrier element, as with the Figure 3 embodiment, with a conventional insert in the form of a nut 27c, also as in the Figure 3 embodiment, being engaged on the screw thread 28, to force the washer downwardly when the nut is tightened.
• the washer is of a diameter much greater than that of the bore 12c at the top of the stopper rod body.
• the washer could be sized to be received in the upper end of bore 12c and thus at least partly received therein when it axially compresses the seals 25a, 25b.
• the insert screw-threaded on the carrier rod, such as nut 27c could also at least partly be received in the bore 12c pressing down on the washer.
• the further sealing means could, in any embodiment, be a single seal or any suitable number of seals.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
• Continuous Casting (AREA)
• Treatment Of Steel In Its Molten State (AREA)
• Lift Valve (AREA)
• Coating Apparatus (AREA)

Priority Applications (12)

Applications Claiming Priority (4)

Publications (2)

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Family Applications (1)

Country Status (15)

Cited By (1)

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Citations (3)

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• 2006
  • 2006-06-01 KR KR1020087000086A patent/KR20080016723A/ko not_active Application Discontinuation
  • 2006-06-01 CA CA002610580A patent/CA2610580A1/en not_active Abandoned
  • 2006-06-01 EP EP06744052A patent/EP1885516B1/en active Active
  • 2006-06-01 JP JP2008514190A patent/JP2008542032A/ja active Pending
  • 2006-06-01 WO PCT/GB2006/001991 patent/WO2006129091A2/en active Application Filing
  • 2006-06-01 TW TW095119400A patent/TW200709873A/zh unknown
  • 2006-06-01 EA EA200702645A patent/EA200702645A1/ru unknown
  • 2006-06-01 DE DE602006020436T patent/DE602006020436D1/de active Active
  • 2006-06-01 AU AU2006253947A patent/AU2006253947A1/en not_active Abandoned
  • 2006-06-01 MX MX2007015023A patent/MX2007015023A/es unknown
  • 2006-06-01 AT AT06744052T patent/ATE500012T1/de active
  • 2006-06-01 US US11/921,090 patent/US20090152778A1/en not_active Abandoned
  • 2006-06-01 BR BRPI0610966A patent/BRPI0610966A2/pt not_active Application Discontinuation
  • 2006-06-02 AR ARP060102310A patent/AR055963A1/es unknown
• 2007
  • 2007-11-30 TN TNP2007000451A patent/TNSN07451A1/en unknown

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