Note: Descriptions are shown in the official language in which they were submitted.
CA 02298399 2000-02-16
BACKGROUND OF THE INVENTION
This invention relates to an apparatus for extracting an
insert from the bottom of a steel-making ladle . More part-
icularly the invention relates to an apparatus which extracts
both a porous plug and a nozzle from a ladle while the ladle
is at normal operating temperature.
Steel is conventionally made in a ladle heated to a temp-
erature at which the constituents of the steel become molten.
The constituents are mixed by gases which are introduced
through a so-called "porous plug" into the ladle . Molten steel
is drawn from the ladle through a nozzle at the bottom of the
container.
The nozzle and porous plug are conventionally mounted
within blocks formed of refractory material and the blocks
extend through openings in the bottom of the ladle. Mortar is
usually used to bind the nozzle and plug to the blocks.
After repeated use, a nozzle and a porous plug become
eroded to a point where they are no longer useful. When the
plug and nozzle are to be replaced, the mortar which binds
them to the block must first be broken. The steps involved in
breaking the mortar are difficult and time consuming. First
the ladle must be emptied then cooled to ambient temperature.
The mortar must then be chipped away by means of a jack-hammer
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to separate the nozzle and plug from the block so that they
can be removed and replaced.
The condition of the block and the refractory lining of
the ladle is severely damaged at the time the nozzle and por-
ous plug are being removed. The reason is that the thermal
shock sustained by the refractory material as its temperature
drops from operating to ambient temperature causes it to
spall. The violent vibrations caused by the hammering action
of the jack-hammer also causes spalling. Major repairs of the
lining and the blocks are usually required before the ladle
can be returned to service.
SUMMARY OF THE INVENTION
The extracting apparatus of the subject invention over-
comes the problems described above . The nozzle and porous plug
are removed smoothly by pneumatic means and not violently by
a jack-hammer. Moreover they can be removed while the ladle is
at operating temperature so that the refractory lining and
blocks are not damaged by thermal shock.
Removal of the nozzle and porous plug at operating temp-
erature gives rise to a significant savings in the cost of
energy over the conventional practice of removal at ambient
temperature. The conventional practice requires that the ladle
be reheated to restore it to operating temperature after the
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nozzle and porous plug are removed. Considerable time and en-
ergy ire required to accomplish that . No such time is lost nor
energy expended according to the practice of the subject in-
vention.
The subject extracting apparatus has a gripper for re-
moving a porous plug and a nozzle-extractor for removing a
nozzle. The two parts are interchangeable so that both a
nozzle and plug may be extracted by the same apparatus.
DESCRIPTION OF THE DRAWINGS
The extracting apparatus of the invention is described in
detail with reference to the accompanying drawings in which:
Figure 1 is an elevation of the extracting apparatus used
to remove a nozzle in conjunction with a steel-making ladle
and a dolly for supporting the apparatus;
Figure 2 is an enlarged elevation of the extracting
apparatus used to remove a porous plug in conjunction with a
steel-making ladle and a dolly;
Figure 3 is an enlarged end view of the gripper for
extracting a nozzle, partly cut away, in conjunction with a
ladle;
Figure 3A is an enlarged elevation of the forward end of
the nozzle extractor;
Figure 4 is an enlarged elevation of the gripper for
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extraction of a porous plug, partly cut away, in conjunction
with a ladle.
Figure 5 is an enlarged end view of the carriage il-
lustrated in Figures 1 and 2;
Figure 6 is a plan view of the dolly for supporting the
extracting apparatus;
Figures 7 and 8 are enlarged elevations of the gripper
for extracting a nozzle;
Figures 9 and 10 are enlarged elevations of the gripper
for extracting a porous plug; and
Figure 11 is a perspective view of the gripper for ex-
tracting a porous plug.
Like reference characters refer to like parts throughout
the description of the drawings.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
With reference to Figures 1,2 and 3, the extracting ap-
paratus of the invention, generally 10 is connected to a dolly
12. The apparatus is adjacent to a steel-making ladle 14 which
has a porous plug 16 and a nozzle 18. The size of the plug and
nozzle is exaggerated relative to the ladle for a better un-
derstanding of the apparatus. In some drawings the plug is
above the nozzle, for example in Figures 1 and 3 and in some
the plug is below the nozzle, see for example Figures 2 and 4.
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As is well known, gases used in the steel making oper-
a.tion'are introduced into the molten steel through a pipe 20
(Figure 3) which extends from the exterior of the ladle and
through the porous plug to the interior of the ladle. Molten
steel in the interior of the ladle is extracted through the
nozzle.
With reference to Figure 4, the interior of the ladle is
lined with refractory material 22 and both plug and nozzle are
mounted in blocks 24, 26 also formed of refractory material.
As is conventional the plug and nozzle are attached to the
blocks by means of mortar or other binding agent to prevent
leakage of the molten steel through the space between the
blocks and the nozzle and plug.
With reference to Figures 1,2 and 6, the dolly has an up-
right mast 30 which extends upwardly from a base in the form
of a rectangular frame composed of parallel end members 32,
32a and side members 36, 36a. The frame is reinforced by par-
allel intermediate members 34, 34a. The frame is mounted on
castors 38.
The extracting apparatus is attached to a carriage 40
having wheels 42 which run along opposite sides of the lower
flange 44 of an I beam 46. The I beam is attached to the mast
by means of a cylinder 48 which is welded to one end of the I-
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beam. The cylinder is pivotally mounted in bushings formed in
spaced ears 54, 56 and the ears are connected to a plate 58.
The plate is attached to the mast by means of bolts 60 which
extend through apertures in the plate and in the mast. A num-
ber of such apertures are formed in the mast so that the
height of the beam can be varied.
An upper horizontal beam 62 is welded to the upper end of
the mast and an ear 64 extends downward from the end of the
beam for supporting a chain hoist as described below.
Preferably the components which make up the dolly are I-
beams or channels formed of steel.
With reference to Figure 3 the nozzle-extracting ap-
paratus of the invention includes a housing 70 within which an
elongated rod or ram 72 is mounted. An actuator 74 such as a
hydraulic or pneumatic cylinder is also mounted within the
housing and the ram extends through the actuator and outwardly
through an opening in the forward end of the housing. The act-
uator causes the ram to advance toward the ladle and to with-
draw from it in a direction coaxial with the longitudinal axis
72a-72a of the ram.
The ram is composed of two segments, a rear segment 72b
within the housing and a forward segment 72c partly inside and
partly outside the housing. The two segments are intercon-
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nected by means of a joint 76 composed of a vertical hub 78
and a~pair of horizontal pegs 80. The pegs extend outwardly
from diametrically opposite sides of the hub and into openings
in the two ram segments. The ram segments are maintained in
the openings by means of cotter pins (not illustrated) which
extend through apertures in the pegs and the rams. By removal
of the cotter pins, the two ram segments may be disconnected
from the joint.
A nozzle-extractor is pivotally mounted to the forward
end of the ram. The extractor is in the form of a bar or pin
90 which pivots between first and second positions. In the
first position illustrated in Figure 3A, the pin is horizontal
and its longitudinal axis coincides with the longitudinal axis
72a-72a of the ram as extended. When the pin is in this pos-
ition, it fits into the bore 92 of the nozzle 18 so as not to
inhibit the advance and retraction of the ram within the bore.
In Figure 3 the pin is in the second position. In that
position the pin is vertical and is adapted to contact the
interior end wall 94 of the nozzle such that when the ram is
withdrawn from the bore, the pin draws the nozzle from the
ladle.
One end 90a of the pin is heavier than the other end and
when ram 72 is horizontal, gravity will cause the heavier end
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to swing downward. As a result the pin will normally be in the
second position. In that position, the pin may bind with the
wall of the bore of the nozzle as it is being inserted through
the bore of the ram. To hold the pin in the first position so
that it can be inserted into the bore without binding, duck
tape is wound around the pin and ram. If the pin is inserted
quickly, the tape will hold the pin in the first position un-
til the pin is beyond the interior end wall 94 of the nozzle.
The heat from the ladle will cause the tape to burn and when
that happens, the pin will swing to the second position.
Other frangible material which will break in the heat
from the ladle can be substituted for duck tape.
With reference to Figures 4 and 9-11, a gripper 100 is
substituted for the forward ram segment 72c and the joint 76
of Figure 3 when the apparatus of the invention is used to
extract porous plug 16. The gripper has a channel 101 having
a peg 102 which fits into the opening in the rear segment 72b
of the ram. The gripper may thus be attached to the ram in the
same way as joint 76 of the nozzle extractor.
The gripper has a pair of j aws 104 , 106 pivotal ly mounted
to ears 107 attached to the channel. A boss 108 is attached to
each jaw and a second boss 110 is attached to each flange of
the channel. A coil spring 112 interconnects each pair of
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bosses and serves to resiliently bias the jaws apart from each
other .'
With reference to Figures 9 and 10, an annular shoulder
114 is formed on the inside wall of housing 70. When the ram
is withdrawn, the jaws come into contact with the shoulder and
the jaws pivot toward each other. The shoulder accordingly
serves to oppose the bias of the coil springs.
OPERATION
The steps involved in removing a nozzle using the ex-
tracting apparatus include first~adjusting the height of beam
44 by means of a chain hoist (not illustrated) suspended from
ear 64 of the upper beam. Bolts 60 are removed from the mast
so that I beam 46 may move up and down relative to the mast.
The beam should support the extracting apparatus such that the
ram is at the same level as the bore of the nozzle. When the
apparatus is at the correct position, the bolts are inserted
into the mast to hold the apparatus in position.
Forward ram segment 72c having nozzle-extracting pin 90
at its forward end is then attached to the ram and the pin is
taped into the first position. The pin is advanced into the
bore by means of actuator 74 until it is beyond the interior
end wall 94 of the nozzle. The heat in the bore will cause the
tape to burn away and the pin will rotate into the second pos-
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ition.
The ram is then withdrawn by means of the actuator. The
pin will bear against the interior end wall 94 of the nozzle
with sufficient force to cause the mortar which binds the
nozzle to the block to fracture.
The force required to fracture the mortar is in the order
of 10 tons. The actuator is capable of causing the pinto ap-
ply a force of as much as 100 tons to the interior end wall so
that there is ample force to fracture the mortar.
The nozzle can then be removed from the block and the
dolly rolled away from the ladle. At this point, the hot used
nozzle can then be removed from the extraction apparatus and
discarded.
The steps involved in removing a porous plug using the
extracting apparatus include most of the steps for removal of
the nozzle. The forward segment 72c of the ram and joint 76
are removed and the gripper assembly is attached to the joint
by insertion of pin 102 into the rear ram segment and securing
it therein by means of a cotter pin or other means.
The ram is then extended sufficiently by means of the cy-
linder until the jaws of the gripper are outside housing 70.
The dolly is positioned such that pipe 20 of the plug is be-
tween the jaws of the gripper. The ram is then retracted by
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means of the actuator thereby bringing the shoulder 114 of the
housing into contact with the jaws with resulting clamping of
the jaws to the pipe.
Further withdrawal of the ram causes the bond between the
plug and the block in which it is located to fracture . The
plug can the be removed in a manner similar to removal of the
nozzle.
At the time the nozzle and porous plug are being extract-
ed, the ladle will be under continuous fire. There is no ne-
cessity to allow it to cool during this time.
It will be understood of course that modifications can be
made in the preferred embodiments illustrated and described
herein without departing from the scope and purview of the
invention as defined in the appended claims.
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