Dispensing – Molten metal dispensing – Flow controllers or assists
Patent
1999-03-17
2000-02-22
Kastler, Scott
Dispensing
Molten metal dispensing
Flow controllers or assists
266271, B22D 4108
Patent
active
060269979
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION
This invention relates to a stopper rod and particularly to a means of attaching a stopper rod to a lifting and lowering mechanism.
Stopper rods are well known for use in controlling molten metal flow from a vessel, e.g. a tundish, into a mould. A stopper rod is raised and lowered by a suitable mechanism positioned adjacent the vessel and can thereby be used to close fully or partially or open fully the outlet from the vessel, thus controlling flow of the metal from the vessel.
Conventionally, a stopper rod is formed as an elongate one-piece bonded graphite structure by isostatic pressing in a suitable mould. The stopper rod usually has a hollow structure in that it is formed to have a longitudinal, centrally-disposed bore by use of a suitable removable core in the mould. The lower end of the stopper rod bore may be closed or it may be vented to allow gas, e.g. argon, to be passed through the rod.
Thus, in the conventional manufacture of a stopper rod, the desired graphite composition is placed around a removable core in a deformable mould, i.e. the graphite composition fills the mould space between the core and the deformable mould. The deformable mould is then placed in a tank of liquid, for example water, and the pressure of the liquid is increased by known means to the pressure required to convert the graphite composition to the desired self-supporting structure. After removal of the isostatically pressed product from the mould, the core is removed to provide the hollow stopper rod.
The upper end of the rod must be provided with means by which it can be attached to the lifting and lowering mechanism. Various prior proposals have been made, including co-pressing a threaded bush in the upper end of the stopper rod to receive a threaded shaft; forming the upper end of the bore of the rod with an internal thread to receive an insert, e.g. of ceramic material, and placing a retaining pin through coterminous holes drilled through the stopper rod and an attachment rod.
While each prior proposal has certain merits, none is entirely successful and it is, therefore, an object of the present invention to provide an improved means of attaching a stopper rod to a lifting and lowering mechanism.
Accordingly, in one aspect the present invention provides a means of attaching a stopper rod in the form of an elongate moulded body having a longitudinal bore to a lifting and lowering mechanism, the means comprising a first sleeve to be moulded in-situ in the stopper rod body to lie coaxially with the stopper rod body in an annular recess surrounding and coterminous with the bore, the sleeve having a pair of circumferentially-spaced inwardly-directed, arcuate flanges, a connecting rod of diameter to fit into the stopper rod bore and of length to extend outside the stopper rod while passing through the first sleeve when the sleeve is in position in the stopper rod, the connecting rod having a pair of circumferentially-spaced, arcuate shoulders of size to pass through the spaces between the flanges of the first sleeve, whereby the connecting rod may be passed through the first sleeve until its shoulders have passed beyond the flanges of the first sleeve and then rotated until its shoulders are in circumferential correspondence with the flanges, and a second sleeve of external diameter to fit in the bore of the stopper rod and having at one end a pair of circumferentially-spaced, arcuate, axially-extending projections, the projections having an internal radius sufficient to accommodate the connecting rod through the second sleeve and the projections being of a size to fit into the spaces between the flanges of the first sleeve whereby the shoulders of the connecting rod may be locked beyond the flanges of the first sleeve.
In a second aspect, the invention provides a stopper rod fitted with the means of attachment to a lifting and lowering mechanism as defined in the immediately preceding paragraph.
The connecting rod is preferably externally-threaded, at least for a portion of its len
REFERENCES:
patent: 5303905 (1994-04-01), Pohl et al.
patent: 5681497 (1997-10-01), Labod
patent: 5695675 (1997-12-01), Labod
patent: 5851414 (1998-12-01), Ando et al.
Kremer Alfred
Langer Gerhard
Foseco International Limited
Kastler Scott
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