Dispensing – Molten metal dispensing – Flow controllers or assists
Patent
1998-02-07
2000-02-15
Kastler, Scott
Dispensing
Molten metal dispensing
Flow controllers or assists
266 45, 266275, 264314, C22B 4108
Patent
active
060242604
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a tundish impact pad, i.e. a pad of erosion resistant material positioned on the floor of a tundish to receive the incoming stream of molten metal poured into the tundish from a ladle.
U.S. Pat. No. 5,169,591 shows an impact pad for a tundish for continuous casting of steel that is a significant advance over the art. The impact pad, as illustrated and described in that patent, can substantially eliminate surface turbulence in a continuous casting tundish as well as providing other advantages including minimisation of slag entrainment within the liquid steel bath in the tundish, prevention of the break-up of tundish flux cover and reoxidation of the liquid steel bath and ensuring a proper flow path of the steel within the tundish.
The particular design of the impact pad actually illustrated in the drawings of the U.S. Pat. No. 5,169,591 may be ideally suited for certain combinations of tundish design and casting conditions, while for other combinations of tundish design and casting conditions a modification thereof is more desirable. It has been found, therefore, according to our U.S. Pat. No. 5,518,153, that particularly for combinations of tundish design and casting conditions where the additional benefits of increased inclusion flotation or reduced volume of mixed steel chemistry upon grade changes are sought, it is desirable to provide an impact pad having an annular (closed) configuration. It has also been found, according to that invention, however, that the annular configuration must be non-uniform. That is, the opening provided in the impact pad into which the liquid steel flows must be longer along the long axis of the tundish than it is along the short axis. The preferred configuration of the impact pad is rectangular, although oval or other polygon shapes may be provided as long as they are non-uniform (e.g. not circular or square).
Thus, in U.S. Pat. No. 5,518,153, there is described a tundish impact pad formed from a refractory composition capable of withstanding continuous contact with molten metal, said pad comprising a base having an impact surface and an endless outer side wall extending upwardly therefrom and fully enclosing an interior space having an upper opening for receiving a stream of said molten metal, said outer wall including an annular inner surface having at least a first portion extending inwardly and upwardly toward said opening, whereby, when a downwardly directed stream of molten metal from a location disposed above said impact pad strikes said impact surface, said stream is directed outwardly toward said annular inner surface and then redirected upwardly and inwardly toward the incoming molten metal stream.
More specifically, the impact pad described in one embodiment in that patent has an annular inner surface which further includes a second portion extending outwardly and upwardly from said impact surface towards said first portion of the annular inner surface. One or both of the first and second portions are of concave annular shape and the first and second portions may be continuous. Thus, the annular inner surface may be semi-circular about an axis substantially parallel to the impact surface thereby providing a sidewall with a semi-circular interior face around the entire periphery of the impact surface. This pad, therefore, has no interior corners so as to avoid the possibility of molten steel collecting in such corners and eroding the refractory material of the impact pad.
In U.S. Pat. No. 5,358,551 is disclosed an impact pad for a tundish, the pad having a continuous upstanding sidewall surrounding a flat impact surface, the sidewall having an inclined or curved inner surface forming an annular portion extending inwardly and upwardly to the opening into the pad.
In DE-A-2224482 is disclosed a tundish whose floor beneath a casting spout has an upwardly pointed, raised portion, conical in section, with a trough in the floor at each side of and adjacent the base of the conical section. This construction is intended to remove alumina inclusio
REFERENCES:
patent: 1177240 (1916-03-01), Gates
patent: 3470284 (1969-09-01), Hartmann
patent: 5169591 (1992-12-01), Schmidt
patent: 5358551 (1994-10-01), Saylor
patent: 5518153 (1996-05-01), Zacharias et al.
Isenberg-O'Loughlin, "Dishing It Out, The Latest in Tundish Utensils and High-Tech Tableware" Metalproducing, No. 33, Feb. 1996.
Jardine Bryce R.
Zacharias Donald R.
Foseco International Limited
Kastler Scott
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