Metal founding – Means to shape metallic material – Continuous or semicontinuous casting
Patent
1991-03-06
1993-03-09
Lin, Kuang Y.
Metal founding
Means to shape metallic material
Continuous or semicontinuous casting
222594, B22D 1110
Patent
active
051919265
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a device for slag-free pouring into a continuous casting machine with a slide gate nozzle at the discharge orifice of a tundish and a starting pipe blocking the inlet of the discharge orifice when filling the tundish.
Such devices have as a goal to allow only clean or pure molten metal at as high as possible a temperature or without significant heat loss through cooling into the discharge opening of the tundish and thus through the slide gate nozzle into a mold of the continuous casting machine.
A refractory starting pipe with an ideal break point having the shape of an annular slot and breaking under the burn-through effect and/or the buoyancy of the molten metal is disclosed in DE-OS 3 701 707. The broken off piece of pipe floats and thus clears the way for the melt to the discharge orifice of the vessel via the remainder of the pipe that remains in position at the bottom of the vessel. Thus, the opening procedure is a function of the functional efficacy of the ideal break point at a desired instant. If the ideal break point does not break in time, the break must be produced by manipulating a rod from the outside, a process that is irksome and, especially in the case of multistrand machines, time-consuming and expensive. On the other hand, the ideal break point can function earlier than intended so that slag floating on the molten metal is carried along into the discharge orifice and deposited into the mold via a dummy bar head thereof. Such non-metallic nests in the mold always mean a risk associated with the breakthrough of the melt when the dummy bar starts to withdraw.
Therefore, in the practice one usually drops the application of covering flux for thermal insulation and air shielding of the melt directly after generation of a melt level in the tundish. This does not occur until after the release of the molten metal flow by means of the starting pipe so that a significant heat loss and reoxidation of the melt must be taken into account, a state that can be the cause of melt deposits or freezings forming by themselves in the slide gate nozzle.
SUMMARY OF THE INVENTION
The object of the present invention is to provide improvements with respect to the action of a starting device of the aforementioned type and to facilitate primarily automatically a timely release of slag-free melt at the starting pipe.
This object is achieved according to the invention in that a separate starting member, floating with the rising melt level starting from a predetermined filling level in order to release the molten metal flow, is loosely positioned relative to the starting pipe. In this manner, the release of the starting member and thus the release of the melt outflow is solely dependent on the buoyancy potential of the starting member, which is determined by the choice of body height and the free length of the starting pipe. This means that the liberating or release phase runs its course unimpeded, in contrast to ta device in which a detachable part is arranged on a stationary part by means of a connection that must be destroyed. When seen as a whole, the pouring of a continuous casting machine becomes more reliable, more accurate and more on time, even for multistrand continuous casting machines. In addition, the melt level forming in the tundish can be coated early with a covering flux, which keeps the melt warm and thus prevents freezings in the slide gate valve, without having to fear that the slat and covering flux will drain together with the molten melt into the mold.
In detail, the procedure according to the invention is that a hollow starting member forms an elongation of the starting pipe by resting loosely on an inlet end thereof. To this end, a hollow cylindrical member is advantageous in that it can be readily manufactured and can be effectively heated prior to use together with the tundish. Thus, it is advantageous to provide the starting member with a guide that forms an annular slot between the member and the pipe, that extends along the interior
REFERENCES:
patent: 4394006 (1983-07-01), Bedell
patent: 4526349 (1985-07-01), Schwer
Lin Kuang Y.
Metacon AG
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