Metallurgical apparatus – Process – Plugging or tapping
Patent
1997-02-26
1998-06-16
Kastler, Scott
Metallurgical apparatus
Process
Plugging or tapping
266230, 222594, B22D 4300
Patent
active
057665435
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a flow control device for the outlet of a molten metal handling vessel, e.g. a ladle or a tundish. It is particularly concerned to provide a device which limits the formation of vortexing effects during the discharge of the molten metal, e.g. molten steel from a tundish.
For convenience the invention will be further described below with particular reference to the discharge of molten steel from a tundish although it will be appreciated that its application is not so limited.
As steel empties through the discharge outlet in a tundish a vortex effect can commonly occur around the outlet. This is undesirable as it can cause the entrainment of slag or other impurities into the steel passing from the tundish.
There has been a number of prior proposals to eliminate or reduce this unwanted vortex effect. For example, International Application PCT/CA 93/00529 describes a flow control device comprising a baffle plate and a plurality of dividers radially disposed to space the plate above an outlet nozzle of, e.g. a tundish. The radial dividers cause the steel to approach the nozzle outlet in several convergent radial streams whereby vortex entrainment can be eliminated.
JP-A-63 0668 teaches a flow control device to prevent vortex-formation in a tundish, which device has a head portion in the form of four vertical spaced blades of cruciform plan form and which is attached by a support rod to the lid of the tundish.
One problem with most prior proposals to reduce vortexing is that the proposed device has to be positioned in the, e.g. tundish prior to filling with molten steel and must then last for the life of the sequence of casting being employed. Even though it is possible to manufacture devices with such a life span, they are subject to considerable build up of oxides created by the complex flow with the result that the outlet flow area can be restricted, which can cause unwanted problems with the casting.
The present invention aims to provide a flow control device that overcomes these deficiencies of the prior art.
Accordingly, in one aspect the invention provides a flow control device for the outlet of a molten metal handling vessel, the device having a head portion and a tail portion and flow channels defined between the head and tail portions, the tail portion being contoured to fit into a correspondingly contoured entrance to the outlet with the flow channels leading into the outlet, the device being attached to a refractory positioning means whereby it can be fitted into the outlet during flow of the molten metal through the outlet, wherein the head portion comprises a baffle plate to cover the outlet to reduce vortex effects in the molten metal.
In another aspect the invention provides a method of controlling the flow of molten metal through an outlet from a vessel in which a flow control device having a head portion and a tail portion is positioned so that its tail portion fits into a correspondingly contoured entrance to the outlet whereby flow channels defined between the head and tail portions lead into the outlet, characterised in that the head portion comprises a baffle plate which covers the outlet and the fitting is effected during the flow of the molten metal through the outlet by a refractory positioning means attached to the device.
The refractory positioning means may be, for example, a refractory arm or shaft, e.g. a tube, which may be disposable, attached at one end to the flow control device, usually to its head and of sufficient length to be manoeuvred from above the surface of the molten metal, preferably from outside the vessel. The shaft may, if desired, be integrally formed with the head of the device.
Most conveniently the flow control device is positioned in the outlet towards the end of the pouring of the metal through the outlet, whereby the aforesaid disadvantages of oxide build up may be avoided. Thus it may be inserted towards the end of the last "heat" being discharged in a sequence from a tundish.
The device may be manually positioned in the outlet usin
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Foseco International Limited
Kastler Scott
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