Dispensing – Molten metal dispensing – Flow controllers or assists
Reexamination Certificate
2001-06-29
2003-04-29
Kastler, Scott (Department: 1742)
Dispensing
Molten metal dispensing
Flow controllers or assists
Reexamination Certificate
active
06554167
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a tundish impact pad, and more particularly to a tundish impact pad that reduces flashing and rebound due to a misaligned, incoming metal stream.
BACKGROUND OF THE INVENTION
Liquid metal, in particular liquid steel, is often poured from one vessel to another. For example, liquid metal may be poured from a furnace into a ladle, and then from a ladle into a tundish and from a tundish into a mold. When liquid is poured into the tundish from a ladle, it is normally poured into the tundish through an outlet in the bottom of the ladle. The stream of metal from the ladle is metered by a valve and the outlet stream may be enclosed in a ceramic tube, called a ladle shroud, which extends downward from the ladle bottom.
A typical tundish is a trough or box-shaped vessel having a generally horizontal or flat bottom with vertically arranged walls. The stream of metal poured from the ladle, i.e., incoming ladle stream or flow, enters the tundish and impacts the tundish bottom and spreads in all directions. It is known to use tundish impact pads to try and control an incoming ladle stream to reduce erosion of the tundish lining and to effect certain desirable flow patterns in the tundish. In this respect, prior patents purport to control the flow of the molten metal to prevent non-separation of slag and inclusion particles, to prevent disturbance of smooth, metal flow, and further to prevent thermal inhomogeneity, i.e., short circuit flow and different liquid metal residence times.
Attaining the desired flow patterns requires that the incoming stream from the ladle contacts the bottom of the tundish at a specific location, which is to say it encounters the impact pad at a specific location, generally the geometric center of the pad. However, exact control of an incoming ladle stream is difficult, and it is not unusual for an incoming stream to be slightly off center from its desired location. With cup-shaped impact pads, a misaligned ladle stream can cause the liquid metal to impact the upper surface of the impact pad thereby causing the incoming stream to splash in all directions. Such a misaligned stream would quickly erode the top and side wall of the impact pad, thereby defeating the purpose of the impact pad and possibly exacerbating the problems the pad was intended to overcome.
The present invention overcomes these and other problems and provides an impact pad having an upper collar adapted to redirect misaligned streams toward the center of the impact pad to reduce the likelihood of lateral splashing and rebounding.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided an impact pad for receiving a stream of liquid metal having a bottom wall with an upper surface against which said liquid metal is intended to impact, a side wall extending in an upward direction along the periphery of the bottom wall, and an annular wall extending inwardly from the side wall. The annular wall, together with the bottom wall and side wall, define a metal receiving chamber having an opening through the annular wall. An upward extending collar wall extends along the periphery of the impact pad above the throat opening. The collar wall has a contoured inner surface merging with an upper surface on the annular wall for directing a stream of liquid metal offset from the opening back toward the opening.
It is an object of the present invention to provide an impact pad for receiving a stream of molten metal.
It is another object of the present invention to provide an impact pad as described above that dampens and contains a stream of molten metal.
It is another object of the present invention to provide an impact pad that accommodates a slightly misaligned incoming metal stream.
It is another object of the present invention to provide an impact pad as described above which reduces the likelihood of lateral splashing of a slightly misaligned incoming metal stream.
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Metal Producing, pp21-23 and 47, “Taming the Thunder” Isenberg-O'Loughlin, Sep.-1994.
Jaffe Michael A.
Kastler Scott
Kusner Mark
North American Refractories Co.
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