Closing or regulating apparatus for a metallurgical vessel

An apparatus for closing and/or regulating the discharge or tapping of molten metal from a metallurgical vessel includes a refractory outer pipe member having therethrough a discharge passage defining outer and inner openings and a refractory inner pipe member positioned within the outer pipe member, the inner pipe member having therethrough a passage defining outer and inner openings. A first of the pipe members is movable with respect to a second of the pipe members between open and closed positions. In the opened position, the discharge passages of the pipe members are aligned to define a molten metal discharge channel for passage therethrough in a flow direction of molten metal from an inlet opening to an outlet opening of the discharge channel. The cross-sectional area of the discharge channel is a minimum at the inlet opening and is increased between the inlet opening and the outlet opening.

BACKGROUND OF THE INVENTION 
The present invention relates to an apparatus for closing and/or regulating 
the discharge or tapping of molten metal from a metallurgical vessel. More 
particularly, the present invention relates to such an apparatus including 
a refractory outer pipe member having therethrough a discharge passage 
defining outer and inner openings, and a refractory inner pipe member 
positioned within the outer pipe member, the inner pipe member having 
therethrough a discharge passage defining outer and inner openings. A 
first of the pipe members is movable, for example, rotatable or axially 
movable, with respect to a second of the pipe members between an opened 
position, whereat the discharge passages of the pipe members are aligned 
and with the inner opening of the outer pipe member confronting the outer 
opening of the inner pipe member, thereby defining a molten metal 
discharge channel that enables flow of molten metal through the pipe 
members in a flow direction from an inlet opening that receives molten 
metal from within the metallurgical vessel to an outlet opening to 
discharge the molten metal, and a closed position, whereat the discharge 
passages of the two pipe members are out of alignment and the inner 
opening of the outer pipe member and the outer opening of the inner pipe 
member are isolated from each other enclosed, thereby interrupting the 
discharge channel. 
A closing and/or regulating apparatus of this general type is disclosed in 
German DE 37 31 600. In this type of device however, when the apparatus is 
in a closed position, molten metal will fill the discharge passage or 
passages through the outer pipe member but will not flow since the 
apparatus is closed. This molten metal can solidify or partially solidify 
within such discharge passage and form a solidified metal skin or small 
metal plug. Thereafter, when the movable pipe member is moved to the open 
position to open the apparatus, this frozen metal skin or metal plug can 
cause clogging of the molten metal discharge channel and prevent tapping 
of the molten metal. Thus, opening of the apparatus cannot be ensured 100 
percent of the time, and this is an operational disadvantage. 
In U.S. Pat. No. 3,511,471 there is disclosed a rotary slide gate or 
sliding closure unit having through various members discharge passages 
than can be aligned to form a discharge channel. The inlet opening to this 
discharge channel converges in a downstream direction. The result is that 
when the slide gate is in a closed position, a metal skin or metal plug 
that will form in the inlet discharge passage cannot be discharged with 
certainty upon subsequent opening of the apparatus. This is true even 
though this known slide gate discloses the downstream portions of the 
discharge channel diverge in a downstream direction. 
Swiss Patent CH-PS 420,498 discloses a discharge apparatus where the 
relative position of a casting stream is changed by moving one member that 
partially forms a discharge channel. In this case, at least portions of 
the discharge channel converge in a downstream direction, and the above 
problem also occurs. 
SUMMARY OF THE INVENTION 
With the above discussion in mind, it is an object of the present invention 
to provide an improved apparatus for closing and/or regulating the 
discharge or tapping of molten metal from a metallurgical vessel, whereby 
it is possible to overcome the above and other prior art disadvantages. It 
is a more particular object of the present invention to provide such an 
apparatus whereby it is possible to ensure that when the apparatus is 
moved from a closed position to an open position, any solidified metal 
skin or metal plug formed in a discharge passage of an outer pipe member 
automatically and positively will be discharged in a downstream direction 
through the discharge channel. 
It is a further object of the present invention to provide inner and outer 
pipe members employable in such a closing and/or regulating apparatus. 
The above objects are achieved in accordance with the present invention by 
the provision that the flow cross section of the discharge channel is 
expanded from the inlet opening thereof to the outlet opening thereof. In 
other words, the cross-sectional area of the discharge channel is at a 
minimum at the inlet opening and increases between the inlet opening and 
the outlet opening. 
As a result of this structural arrangement, when the apparatus is in a 
closed position with molten metal in the metallurgical vessel, then molten 
metal that freezes in the discharge passage in the outer pipe member 
automatically will be expelled through the discharge channel without 
causing clogging thereof upon subsequent opening of the apparatus. More 
specifically, the molten metal can be allowed to freeze to form a metal 
skin or metal plug within the discharge passage in the outer pipe member, 
in the region of the inlet opening and optionally as far as the inner 
opening thereof. When the apparatus subsequently is opened, then due to 
the fact that the cross-sectional area of the discharge channel is 
expanded in the downstream direction, the pressure of the molten metal 
within the metallurgical vessel will push any solidified metal skin or 
metal plug in the flow direction through the discharge channel and 
outwardly of the outlet opening thereof. Thereby, it is possible to ensure 
that the apparatus of the present invention will enable, 100 percent of 
the time, opening of the apparatus and immediate tapping of the molten 
metal therethrough. 
In accordance with one embodiment of the present invention, the outer pipe 
member is a stator of the apparatus, and the inner pipe member is a rotor 
of the apparatus. Thus, the inlet opening of the discharge channel 
comprises the outer opening of the outer pipe member, and the outlet 
opening of the discharge channel comprises the inner opening of the inner 
pipe member. 
In accordance with one feature of the present invention, the 
cross-sectional area of the discharge passage through the outer pipe 
member increases from the outer opening thereof to the inner opening 
thereof, and in a particular embodiment, this increase is conically from 
the outer opening to the inner opening. Similarly, the cross-sectional 
area of the discharge passage in the inner pipe member can increase from 
the outer opening thereof to the inner opening thereof, and this increase 
may be conically from the outer opening to the inner opening. It is 
possible however to provide an arrangement whereby the increase occurs 
only in the discharge passage in the outer pipe member, with the 
cross-sectional area of the discharge passage in the inner pipe member 
being at least partially substantially the same as the cross-sectional 
area at the inner opening of the outer pipe member. 
In accordance with a further arrangement of the present invention, the 
cross-sectional area of the discharge passage in the inner pipe member is 
at least partially greater than the cross-sectional area of the inner 
opening of the outer pipe member. The cross-sectional area of the 
discharge passage in the inner pipe member may increase from the outer 
opening thereof to the inner opening, and this increase can be conically. 
In accordance with a further arrangement of the present invention, the 
cross-sectional configuration of the discharge passage in the outer pipe 
member is uniform from the outer opening thereof to the inner opening 
thereof. The cross-sectional area of the discharge passage in the inner 
pipe member may increase, for example conically, from the outer opening 
thereof to the inner opening thereof. Further, the cross-sectional area of 
the discharge passage in the inner pipe member may be greater than the 
cross-sectional area of the discharge passage in the outer pipe member, 
and the cross-sectional configuration of the discharge passage in the 
inner pipe member may be uniform from the outer opening thereof to the 
inner opening thereof. This cross-sectional configuration of the discharge 
passage of the inner pipe member may be circular or non-circular, for 
example oval. Further, the axial centers of the discharge passages in the 
inner and outer pipe members may be coincident or not coincident. When not 
coincident, the axial center line of the discharge passage in the outer 
pipe member may be at a level lower than the axial center of the discharge 
passage in the inner pipe member. 
In accordance with a further feature of the present invention, the 
cross-sectional area of the discharge channel increases stepwise, and this 
stepwise increase may be achieved by providing that the outer opening of 
the inner pipe member is larger than the inner opening of the outer pipe 
member. This arrangement facilitates the discharge of any frozen metal in 
the discharge passage of the outer pipe member into the larger discharge 
passage in the inner pipe member. Such stepwise increase additionally can 
be provided in the discharge channel of the outer pipe member or in the 
discharge channel of the inner pipe member. Even further, plural stepwise 
increases may be achieved in and/or between the discharge passages in the 
inner and/or outer pipe members.

DETAILED DESCRIPTlON OF THE INVENTION 
In FIG. 1 there is illustrated schematically a lower portion of a 
metallurgical vessel including a bottom 1 with a refractory lining and 
equipped with a closing and/or regulating apparatus 3 according to one 
embodiment of the present invention. Molten metal is intended to be filled 
into an interior 2 of the metallurgical vessel. 
The apparatus 3 includes a refractory ceramic outer pipe member 4 having 
positioned therein a refractory ceramic inner pipe member 5. Outer pipe 
member 4 is sealingly mounted within the bottom of the metallurgical 
vessel and thus forms a stator of the apparatus. Inner pipe member 5 is 
rotatable within outer pipe member 4 around a common longitudinal axis L 
of pipe members 4, 5. Inner pipe member 5 fits within an axial recess 
within outer pipe member 5. Inner pipe member 5 and outer pipe member 4 
have communicating internal channels that axially align to form an outlet 
passage 13. 
With particular reference to FIG. 2, outer pipe member 4 has therethrough a 
discharge passage 6 defining an outer opening 8 and an inner opening 9. 
Similarly, inner pipe member 5 has therethrough a discharge passage 10 
defining an outer opening 11 and an inner opening 12. Inner pipe member 5 
is rotatable relative to outer pipe member 4 about axis L to be moved 
between open and closed positions. At the open position, shown in FIGS. 1 
and 2, discharge passages 6, 10 are aligned with each other with inner 
opening 9 of outer pipe member 4 confronting outer opening 11 of inner 
pipe member 5. This thereby defines a molten metal discharge channel 7 
enabling flow of molten metal through the pipe members in a flow direction 
F from an inlet opening of the discharge channel formed by outer opening 8 
in outer pipe member 4 to an outlet opening of the discharge channel 
formed by inner opening 12 of inner pipe member 5. In a closed position, 
not illustrated, discharge passages 6, 10 are out of alignment, and inner 
opening 9 of outer pipe member 4 and outer opening 11 of inner pipe member 
5 are isolated from each other and closed, thereby interrupting the 
discharge channel and the flow of molten metal therethrough. 
When the inner pipe member 5 is moved to the closed position, then an outer 
peripheral surface of inner pipe member 5 will close opening 9. As a 
result, when molten metal is within interior 2 of the metallurgical 
vessel, such molten metal will enter discharge passage 6 and can solidify 
therein. In accordance with the present invention, the flow cross section 
of the discharge channel formed by discharge passages 6, 10 expands in the 
flow direction F of the molten metal. More particularly, the 
cross-sectional area of discharge channel 7 is a minimum at the inlet 
opening 8 and increases between inlet opening 8 and outlet opening 12. In 
the particular arrangement of the embodiment of FIGS. 1-2, the 
cross-sectional area of discharge passage 6 increases from opening 8 to 
opening 9, and this increase is conically. Similarly, the cross-sectional 
area of discharge passage 10 increases from opening 11 to opening 12, and 
this increase is conically. As a result, when inner pipe member 5 is 
rotated to the open position to align passages 6, 10, then any solidified 
metal within discharge passage 6 will be conveyed by the pressure of 
molten metal within the interior of the metallurgical vessel to pass into 
and through discharge passage 10 and into outlet channel 13. This 
specifically is due to the provision of the increase or expanded flow 
cross section of the discharge channel 7 from the inlet opening 8 thereof 
to the outlet opening 12 thereof. This solves a significant prior art 
problem. This problem particularly occurs with the apparatus in the closed 
position and when initially filling molten metal into the interior of the 
metallurgical vessel. The various elements of the apparatus and 
metallurgical vessel then are at their coolest temperature, with the 
greatest possibility of molten metal solidifying within the blocked 
discharge passage 6. When the apparatus subsequently is moved to its open 
position for teeming of the metal through the apparatus, any solidified 
metal skin or plug automatically and quickly is discharged through the 
remainder of channel 7 and into channel 13. The pressure of the molten 
metal in the metallurgical vessel is sufficient to ensure this operation, 
and this is done quickly and surely without the metal skin or plug 
blocking the channel. 
In the embodiment of FIGS. 1-3, discharge passage 6 expands conically, and 
discharge passage 10 also expands conically at the same conical angle and 
continuing the conical expansion of discharge passage 6. The opening 9 of 
outer pipe member 4 is approximately the same as the opening 11 of inner 
pipe member 5, but as would be understood by one skilled in the art could 
be negligibly or minutely larger. 
In the embodiments of FIGS. 4-8, the discharge channel 7 is expanded 
stepwise. This is achieved by providing that the outer opening of the 
inner pipe member is larger than the inner opening of the outer pipe 
member. Particularly, discharge passage 6 is illustrated as having a 
uniform cross-sectional configuration between openings 8 and 9, and 
particularly a circular-cylindrical cross-sectional configuration. 
In the embodiment of FIGS. 5 and 6, the discharge passage 10 in inner pipe 
member 5 is uniform between openings 11, 12 and is of oval configuration, 
with the longer axis of the oval cross-section extending parallel to 
longitudinal axis L. The center axes of the discharge passages 6, 10 are 
not coincident, i.e. they are staggered vertically as shown in FIGS. 5 and 
6. Particularly, the axial center of discharge passage 6 is vertically 
lower than the axial center of discharge passage 10. 
In the embodiment of FIGS. 7 and 8, discharge passage 10 also is of 
circular-cylindrical configuration. In this embodiment, the axial centers 
of discharge passages 6, 10 are coincident, but could be not coincident. 
In the embodiments of FIGS. 4-8, the cross-sectional area of the discharge 
channel 7 is expanded dramatically between passage 6 and passage 10. Thus, 
any molten metal that tends to solidify in outer passage 6 when the 
apparatus is in the closed position easily will be discharged into the 
abruptly larger cross-sectional area of discharge passage 10 when the 
apparatus subsequently is opened. 
It is to be understood that various combinations of the features described 
in the above embodiments may be combined as would be apparent to one 
skilled in the art. It furthermore is to be understood that other possible 
configurations incorporating the basic concept of the present invention 
are possible. For example, it would be possible to provide that discharge 
passage 6 is conical as shown in FIG. 2 and that the discharge passage 10 
is cylindrical as in FIGS. 7 and 8 or oval as in FIGS. 5 and 6, with 
opening 9 being significantly smaller than opening 11. Other possible 
modifications of the specifically described and illustrated features will 
be apparent to one skilled in the art and are intended to be encompassed 
within the present invention without departing from the scope thereof.