Dispensing – Processes of dispensing – Molten metal
Patent
1991-12-03
1993-03-02
Kastler, Scott
Dispensing
Processes of dispensing
Molten metal
222595, 266239, B22D 4158, B22D 3906
Patent
active
051906740
DESCRIPTION:
BRIEF SUMMARY
The invention relates to method and apparatus for controlling the flow of molten metals from a melt-containing vessel, such as a tundish, into a melt-receptacle, such as a continuous caster.
Hitherto, especially in the field of continuous casting, regulating the flow of molten steel from one vessel to another has been accomplished by means of various refractory stoppers, sliding gate valves or rotary valves. A disadvantage with such devices is that they rely upon the integrity of refractory components moving together. Moreover, they can be expensive to acquire and maintain, and time-consuming to fit and remove. The only currently used flow-control method, of which the applicants are aware, having no moving refractory parts and where no activator is needed, is the metering nozzle system. The limitation of such a system is that the throughput cannot be altered in a controlled manner during casting and, moreover, any significant nozzle-bore erosion or blockage means that casting has to be terminated.
Several flow control systems have previously been described in which moving refractory components have been eliminated and flow of molten metal has been controlled instead through the use of gas pressure. Thus for example, U.S. Pat. No. 3,608,621 describes the use of a refractory column which is located above the discharge nozzle in a holding vessel for molten metal. The lower portion of the column is divided by a weir into an up-flow chamber which has a molten-metal inlet at its lower end, and a down-flow chamber which has an outlet leading to the discharge nozzle at its lower end. The up-flow chamber has an annular array of gas pipes or an annular gas-permeable refractory brick at its lower end just above the inlet. Molten-metal flow through the device is brought about by injecting gas into the molten metal such that the body of metal is caused to spill over the weir into the down-flow chamber. It would appear that this method requires a constant flow of gas during a metal pouring process. The use of a constant flow of gas would not only render the process significantly more costly but in addition could be expected to exert a significant chilling effect on the system.
U.S. Pat. No. 4,394,006 describes a flow control system wherein a gas bubble is created in a chamber above the discharge nozzle of the molten-metal holding vessel. The chamber is defined, in part, by a weir which separates the body of molten metal from the nozzle. The pressure of the gas bubble prevents molten metal from spilling over the weir into the nozzle. Molten metal flow is initiated by reducing the gas pressure in the chamber thereby allowing metal to pass into the chamber and spill over the weir. However, this method suffers from the disadvantage that it is essentially an on-off system which does not allow for fine control and adjustment of molten metal flow rate.
It is an object of the present invention to provide a reliable and sensitive flow-control system in melt-containing vessels, which is capable of being quickly assembled by non-technical personnel, and which requires neither modification of the melt-containing vessel, nor mechanical activation mechanisms. It is a further object of the present invention to provide a means of overcoming the problems of the aforementioned flow-control systems.
The present invention provides a method of controlling the flow of molten metal from a holding vessel such as a tundish through a discharge orifice into a receptacle such as a mould; the method comprising down-flow chamber separate from but in fluid communication with the interior of the holding vessel, the down-flow chamber having an outlet at its lower end, said outlet leading to or forming part of the discharge orifice, and an opening towards or at its upper end; allow molten metal from the holding vessel interior to pass through the opening to establish in the lower end of the down-flow chamber a column of the molten metal, with a volume of gas occupying the upper end of the flow control chamber and serving to separate the column of molten
REFERENCES:
patent: 3552478 (1971-01-01), Lauener
patent: 3608621 (1971-09-01), Bollig et al.
patent: 4340160 (1982-07-01), Van Geel
patent: 4394006 (1983-07-01), Bedell
Patent Abstracts of Japan, vol. 7, No. 104, (M212) [1249], May 6, 1983, & JP, A, 5825863 (Fuji Denki Seiko Ltd.), Feb. 16, 1983.
Buchanan Ingersoll
Kastler Scott
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