Note: Descriptions are shown in the official language in which they were submitted.
CA 02246351 1998-08-07
WO 971308~}7 PCT/EP97/~634
TUNI~ISH EOUIPPED WITH A TUBE CHAN(~ER
AND PLATE FOR THE TUI~E CHANGER
5 The present invention concerns a continuous casting tundish for a sIeel mill, equipped
with at least one tube changer, this changer being comprised of a chassis mounted on
the tl]n~lich, refractory pieces that delimit a pouring channel for passage of the steel
from the tundish to a continuous casting mold, those refractory pieces being comprised
of at least one fixed plate and a tube having a plate at its upper end, means for exerting
pressure for applying the plate of the tube against the fixed plate, their surfaces forming
a junction plane, a position for introducing a new tube, a casting position and a position
for ev~ou~tin~ a worn tube, guidance means that permit the new tube to pass from the
introduction position to the casting position and the worn tube to pass from the casting
position to the evacuation position~ ~tl~ting means for passing the new tube from the
1~ introduction positivn to the casting position and the worn tube from the casting position
to the evacuation position.
An example of such a device is described in the French patent application registered
under N~ 95 05 504. This device presents advantages over the other existing devices,
as described for example in the document EP 0 192 019. However, it has the
shortcoming of requiring cylindrical sliding surfaces for the fixed plate and ~or the tube
plate. To guarantee a good tightn~ss of the plates, it iS nPceC~ry that the radii of the
fixed plates and the tube plate be absolutely identical, which involves difficulties in
machining. Furthermore, these plates are subject to thermal stresses during casting and
it is not certain that the deformations caused by their thermal expansion are identical
over the entire periphery of the plates, which can cause a lack of tightness between
these plates. It is also known that the pouring channel in such a device is generally
under a lower pressure than atmospheric pressure. To avoid any aspiration of air tha~
would cause a chemical perturbation and degradation of the steel quality, at least one
groove that runs completely around the pouring channel is generally provided in one
of the fixed of mobile plates, this groove being supplied with a neutral gas undet
CONFIRMATION COPY
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pressure, such as argon for example, such that any aspiration is that of neutral gas that
does not cause a chemical degradation of the steel. The machining of such grooves on
cylindrical plates proves extremely difficult and costly.
S The present invention concerns a tundish equipped with a tube changer that has the
same advantages as the device described above but not the disadvantages.
According to the principal characteristic of the invention, the junction plane is inclined
at a nonzero an~le (o~) relative to the horizontal; the new tube passes from theintroduction position to the casting position and the worn tube from the castingproduction to the evacuation production by a sliding movement on the junction plane
following a trajectory at least partially not rectilinear, the combination of the angle of
inclination (~) of the junction plane, the dimensions and the trajectories of the tubes
being such that thc tubes avoid the casting mold during a tube change.
The combination of an inclined junction plane and a nonlinear movement makes it
possible to predetermine within a broad range the original and the final positions of the
tubes, an advantage the irnportance of which will be understood better in the following
descriptions.
According to a plerellcd characteristic of the inven~ion, the pla~es of ~he tubes have a
front support face and a rear support face~ the front and rear faces being defined with
respect to the direction of tube change~ the front support face of the new tube plate
coming in contact with the rear support face of the worn tube plate to push it toward
the evacuation position and replace it in the casting position.
According to another preferred characteristic of the invention, the continuous casting
mold has a larger dimension and a horizontal straight line of the Junction plane is
parallel to this larger dimension of the mold. This offers the maximum displacement
possible of the tube inside of the mold.
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According to another preferred embodiment, the tube change is effected along a circular
sliding movement of center O in the junction plane. A rotation in effect offers the
advantage of being extremely easy to effect mechanically.
S According to a particular embodiment of the invention, the center O of the circular
movement is higller than the level where the pouring challnel passes trough the ~unction
plane. This configuration makes it possible to introduce a new tube outside of the mold
and to introduce it by rotation to the inside of the mold while the tube in service
situated inside the mold is removed from the mold during the exchange rotation. This
configuration is adapted more particularly to molds for slabs, the shape of which is
elongated, and which permit movements of the tube longit~-lin~lly inside of the mold.
According to another particular implementation form of the invention, the center O of
the circular movement is lower than the level where Ihe pouring channel passes through
the junction plane. This configuration is particularly adapted for bloom molds. the
section of which is square or nearly square. In such molds the cl-AIlgi~g of an immersed
tube without raising the tundish implies that a new tube could be prepositioned
alongside the tube in service. Considering the narrowness of the rnvld, this implies that
the new tube is inclined so that its end is in the immediate vicinity of the end of the
tube in service at the center of the mold.
According to another particular embodiment, the junction plane between the fi-.ced pla~e
and the tube plate is vertical. The vertical plane is prefera~ly parallel to the major axis
of the mold. This configuration, which guarantees tube movements perfectly aligned
with the maJor axis of the mold is particularly adapted for molds for thin slabs.
According to another particular embodiment, the tube changer is located on the side on
the tundish instead of being placed under the tundish as is generally done. Thisconfiguration permits suppressing a bend in the pouring channel. It also makes a free
space available above the tube changer for the mechanical operations. In the continuous
casting of steel, a device for regulating the flow of steel, e.g., a stopper rod or a slide
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valve, is generally used. The present invention offers new possibilities for combining
the tube and the slide valve closure device. ~n particular, according to one embodiment.
the tundish is equipped with a slide gate between it and the tube changer.
S According to another particular embodiment, the plates of the tubes have rectilinear
support faces, these support faces being inscribed in a sector of center O and with an
angle to the center e~ual to the angle of rotation of the plates during a tube change.
This configuration permits two tube plates to be pushed during the exchange without
ever allowing any play between their support face when the sliding movement on the
junction plane is a rotation.
When the sliding movement is not entirely a rotation, the tube plates preferably have
support faces in the form of concave and convex arcs of a circle, the front support face
of a plate being adapted to the rear support face that precedes it, the support faces
rem~inin~ in contact over a suf~lcient ~iist~nce to completely cover the pouring orifice
at least when the support faces traverse the orifice of the fixed plate during the tube
change. This configuration permits two plates/tubes to be pushed during the exchange
while permanently closing off the pouring orifice.
~0 In a tube changing system the pouring channel is normally perpen~ic~ r to the junction
plane between the fixed plate and the mobile plate. When this junction plane is vertical
or close to vertical, it implies that the pouring channel has the form of a bayonet
between the upper container and the entrance into the fixed plate. This bayonet form
of the pouring channel can present disadvantages. On the one hand, the wear of the
pouring channel can be increased at the level of the bends. On the other, the bends can
favor deposits, e.g., of alumina and cause a sealing of the pouring channel.
To reduce these shortcomings, a particular embodiment of the invention provides for
the pouring channel to cut the junction plane at an inclined angle hl order to reduce the
bayonet effect.
,
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s
in effect, by inclining the angle with which the pouring channel intersects the junction
plane between the fixed plate and the mobile plate it is possible to bring the axis of the
pouring channel closer to the vertical and thus reduce the bayonet effect.
S According to a particular implementation mode, the pouring channel intersects the
junction plane along an inclination angle complementary to the angle of inclination o~
of the junction plane relative to the horizontal so that the pouring channel is rectilinear
over its entire length.
On the other hand, the invention concellls a fixed pla~e for a tube changer equipping
a tundish according to the present invention, as well as a plate/tube assembly for a tube
changer according to the present invention.
The invention is also concerned with a tube adapted to equip a tube changer. It
~5 colllpli~es a tube and a plate having a junction plane adapted to be applied against a
fixed plate of the tube ch~n~r. The junction plane is inclined at a nonzero angle
with respect to the holi;~o~ I when the tube is in casting position.
Other feaLIlres and advantages of the present invention will become evident from a
reading of the following description of implementation examples given by means of
illustration wlth reference to the attached Figures.
Figure I is a Gross sectional view of a preferred embodiment of the invention.
Figure 2 is a perspective view of the tube ch~nging device showll in Figure 1.
Figures 3 and 4 are front views of the tube changing device shown in Figures 1 and 2.
Figures 5 and 6 are respectively a front view and a side view of another implementation
rnode of the invention, in which the center of rotation is lower than the level where the
pouring channel traverses the junction plane.
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Figure 6a is a top view of a mold for blooms.
Figures 7 and 8 illustrate two implementation modes of the invention in which the tube
changer is located on the side of the tundish.
Figure 9 is a view showing the shape of the plates where the circular movement is a
rotation of center 0.
Figure 10 is a view in the Junction plane showing the shape ot the plates when the
movement is different than a pure rotation.
~n Figure 1 a tundish designated by the general reference 2 is comprised of a thick
bottom wall of steel 4 covered with a layer of refractory material 6. A piece ofrefractory material 8, called the fixed plate in the present application, perpendicularly
traverses the bottom wall 4 and the layer of refractory material 6. The fixed plate 8
delimits a pouring channel 10 in its central part. Its upper part 12 forms a seat for a
stopper rod 14 that makes it possible to regulate the flow of the molten steel contained
in the tundish 2 ~llrwgll the pouring channel I0. A bottom plate 16 is fixed under the
bottom of the tl~n-lich. A tube changer designated in its entirety by the general reference
18 is mounted under the bottom plate 16.
The changer 18 is comprised of a chassis 20 mounted in a fixed position under dle
bottom plate 16. The chassis receives the fixed piate 8. For this effect, this plate has
a plane surface 22 by which it rests on the chassis. A rotor 24 is mounted rotatin~ on
the chassis 20 by means of bearings 26. The rotor 24 supports a plate/tube assembly
28 comprised of a plate 30 and of a tube 32. The fixed plate I 8 and the plate 30 of the
plate/tube assembly 28 each have a working face. These working faces are in contact
with each other and define a ~unction plane 34. The plate 30 is applied against the fixed
plate 18 by means for applying pressure 36. In the implementation example shown.these means for applyin~ pressure are comprised of six components with a spherical
head 38 applied on the plate 30 by the springs 40. The pouring channel lO runs through
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the plate/tube assembly to bring the molten steel from the tundish 2 into a castin~ mold
42 into which the tube 32 dips.
Figure 2 is a perspective view of the tube changer shown in Figure 1. The tundish 2
S and the bottom plate 16 are not shown.
It can be seen that the plate 30 essentially has the form of a sector of approximately 9û~
of angle to the center. In the implementation example shown the tube 32 has a quite
elongated section because it is designed for a casting mold for thin slab 42 of very
narrow section.
~igure 2 also shows the ~ct~ i7~tion of the actuating means that permits passing a new
tube from an introduction position (see Figure 3) to the casting position shown in
Figures I and 2, and the worn tube from the casting position to the evacuation position
(see Figure 4). These ~ct~-~ting means are comprised of a pusher 46 having a cross
section in the form of an angle iron that is fitted on an angle of the plate 30. The
pusher 46 is solid and an arm 48 mounted on the rotor 24. The arm 48 is entrained by
means of a jack 50. The jack cylinder 50 is mounted on the boetom plate 16 while its
rod is fixed to the articulated arm 48.
The guidance means that permit the new tube to pass from the introduction position to
the casting position and the worn tube to pass from the casting position tO the
evacuation position are comprised on the one hand of the working face that co",~rises
the junction plane of the fixed plate 8 and on an other hand of the spherical heads 38
of the means for applying ples~ule 36. Due to these means, the working face of the
plate 30 effects a sliding movement on the surface of the junction plane while rem~ining
permanently applied against this surface with a sufficient application force to produce
a rightn~ss to the molten steel.
Figures 3 and 4 are front views of the tube changer shown in Figures 1 and 2. Figure
3 shows a new plate/tube assembly 28a in the introduction position (on the left in the
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Figure). It is introduced into the rotor along a direction perpendicular to the junction
plane. The pusher 46 is equipped with a prepositioning surface 52 on which the plate
30 of the assembly 28a is supported. ~n the other hand, the wor~ing face of the fixed
plate 8, which is a front view on Figures 3 and 4, is not entirely covered by the plate
30 of the plate/tube assembly in the casting position. Two zones designated by 54 are
not covered. The zone 54 situated on the left-hand part of the working face of the fixed
plate 8 (according to the representation of Figure 3) con~tit~-teC a guidance surface that
permits a perfect alignment of the working face of the plate 30 of the new tube with the
junction plane. The zone 54 situated on the right-hand side of the working face of the
fixed plate permits guiding the worn tube during its evacuation.
Figure 4 is identical to Figure 3 with the exception that the new tube was placed in the
working position, and the worn tube in the evacuation position 28b. To pass from the
position shown in Figure 3 to the position shown in Figure 4, the arm 48 was pivoted
by an angle equal to the angle of tube change, in other words, equal to the angle
formed by the sector in which the plate 30 is inscribed. When the new tube passes from
the introduction position to the casting position, it stays clear of the edge of the mold
28. The same is true when it passes from the casting position to the evacuation position.
According to the principal feature of the invention, the junction plane 34 i3 inclined at
a nonzero angle o~ with respect to the horizontal. In the actualization example shown
in Fig 1-4 the angle c~ is equal to 90~. In other words, the junction plane 34 is vertical.
On the other hand, the new tube passes from the introduction position to the casting
position and the worn tube from the casting position to the evacuation position by a
sliding movement on the junction plane, following a trajectory at least partially
nonrectilinear. In the actualization examples of Figures 1-4, this trajectory is circular
with center 0. The point 0 is the center of rotation around which the rotor 24 turns.
This is also the point where the extensions of the support faces of the plates 30
intersect. This actualization variant presents the advantage of being particularly simple
~o realize mech~nir-~lly. It is applicable in particular to thin s}ab casting because it
permits precisely guiding the tube in the mold. It also permits the introduction of the
,
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new tube into the rotor outside of the steel and to withdraw the worn tube entirely
outside of the steel. In this actualization the junction plane 34 is parallel to the large
dimension of the mold.
S Figure ~ shows the working faces 54a and 54b of two plates 30a and 30b (for the sa3ce
of simplification, the tubes are not shown in this Figure). Each of the plates 30a and
30b respectively has a rear support face 56a, 56b and a front support face, 58a and 58b.
The front 58 and rear 56 support faces are defined witll regard to the direction 60 of
plate change. It is evident that the front support face 58a of the plate 30a is in contact
with the rear support face 56b of the plate 30b. These faces are entirely contiguous.
They are applied against each other without leaving a gap for the passage of molten
metal during a plate change. The support faces 56 and 58 intersect at the center 0 of
the circular movement of plate change. The elongated and ellipLical form of the section
of the pouring channel lû at the level where it intersects the junction plane 34 is also
noted on Figure 9. This elongated form is the result of the inclined angle (essen~ially
45~ in the example of Figures 1-4) at which the pounng channel intersec~s the junction
plane. It is also noted that the center 0 of the circular movement is higher than the level
where the pouring channel 10 traverses the junction plane.
''O ~igures S and 6 show another implementation o~ the present invention. The junction
plane 34 is inclined relative to the horizontal at an angle ~ essentially equal to 45".
This angle is the complementary of the angle with which the pouring channel 10
intersects the junction plane. In this manner, the pouring channel is rectilinear over itS
entire length. Contrary to the implementation mode of Figures 1-4t the center ofrotation 0 is lower than the level where the pouring channel passes through the junction
plane 34. Since the angle of plate change is very small. the point 0 is not shown in
Figure 5. This implementation mode is particularly applicable to a mold of s~uare cross
section (mold for blooms) as shown in Figure ~a. A horizontal straight line of the
junction plane 3~ is parallel to the large dimension of the mold 28. which is comprised
here of itS diagonal. In this manner. a new tube 28a and a tube in the casting position
28b can be located at the same time in the mold. A tube change can then be carried OUt
- CA 022463~1 1998-08-07
without raising the distributor by bringing the new tube 28a into the casting position and
the tube 28b into the evacuation position 28c.
Figure 7 shows an implementation variant in wllicll the tul e c'l1anger 18 is located on
the side of the distributor 2 instead of being under it, as is generally the case. This
arrangement pern~its suppressing a bend in the pouring channel 10. It also offers more
space for the mechanism of the tube changer. Finally, a sli-iing plate 62 can beinterposed hetween the working surface of the fixed plate 8 and the working surface of
the fixed plate 30 of the plate/tube assembly 28. The sliding plate 62 regulates the flow
of the molten metal without having to use a stopper rod as is generally done.
Another implementation mode of the invention is shown in Figure 8. The tube changer
is also located on the side of the distributor. The pouring channel 10 is inclined relative
to the horizontal, which makes it possible to reduce the angle of the bend formed by the
pouring channel in the plate/tube assembly 28. A stopper rod 14 is used in this
embodiment to regulate the flow of molten metal in the mold 42.
As Figure 9, Figure 10 shows the working faces of two plates 30a and 30b, viewed in
the junction plane 34. The plates 30a and 30b have support faces in the form of a circle
arc. The rear support faces 56a and 56b have the forms of a concave circle arc. The
front support faces are 58a and 58b. The front support face 58a of the plate 30a fits on
the rear support face 56b of the plate 30b. Their profiles are completely contiguous
without a gap, such that the rnolten metal cannot pass through during a plate change.
The plates 30a and 30b are thus articulated one each other andl one can be displaced
relative to the other in order to follow any profile given by the adapted guides. This
profile can include rectiline~r parts, circu1ar parts or curves of any shape. The front
support face 58a of the plate 30a remains in contact over a sufficient ~ t~nce with the
rear support face 56b of the plate 30b to cover the pouring orifice 10 completely at least
when the support faces 58a and 56b pass through the pouring orifice 10 during a tube
change.
AM~Nl ED SHEET
