Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to rotating
joints and, more particularly, to an improved
rotating joint for tilting furnaces.
It is common for metallurgical furnace
vessels to be tiltable in order to discharge molten
metal therefrom. A discharge conduit :Eor the molten
metal which is connected to the furnace has its
longitudinal axis coincident with the axis of
rotation of the furnace. As the discharge conduit is
stationary, it is necessary to provide a rotating
joint at the junction of the tiltable furnace with
the fixed discharge conduit.
It is standard for such a junction to
include a pair of flanges with a seal positioned
therebetween. One of the flanges is provided near
its periphery with a series of arcuate slots with
bolts extending through these slots and through the
seal and the other flange. This allows for one
flange to rotate as the bolts slidably displace along
the slots.
Such an arrangement allowing a limited
freedom of angular displacement is also used in other
technical fields such as, for instance, in
concrete-pipe joints (U. S. Patent No. 1,475,867
issued on November 27, 1923 to Peterson)..
The above flanged pipe or trough joints of
bolt and slot type are however characterized by a
substantially low life expectancy as either the head
of the bolt or the nut displaces under heavy friction
against the stationary flange when the furnace is
tilted.
U.S. Patent No. 3,291,472, issued on
December 13, 1966 to Hoff, discloses another type of
joint. Indeed, an annular ring is fixedly secured at
right angles to the outer periphery of a drum of the
furnace. The ring thus extends in a radial direction
with respect to the drum. A faceplate which is
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fixedly mounted at the end of a discharge conduit is
juxtaposed to the ring. The faceplate is recessed so
that it is provided with a shoulder which is
juxtapased to the outer peripheral surface of the
annular ring. A backup plate surrounds the drum and
is provided with an inner peripheral diameter which
is smaller than the outer peripheral diameter of the
annular ring with the ring being disposed
intermediate the faceplate and the backup plate. The
faceplate and the backup plate are held in assembled
relationship by means of a plurality of bolts which
extend therethrough at a location outwards of the
annular ring. Therefore, the annular ring will
rotate with the furnace within the groove formed by
the faceplate and the backup plate. Again, heavy
friction is encountered as the annular ring displaces
within this groove while being in contact with both
the faceplate and the backup plate. It is
nevertheless noted that the discharge conduit of the
Hoff Patent reduces the °'down time" to approximately
one half hour which, is insufficient for the furnace
to cool down. However , it is questionable how much
productian is improved as the invention does not
reduce the frequency of repair.
It is therefore an aim of the present
invention to provide a rotating joint for tilting
furnaces which is practically maintenance-free for
resolving the problems associated with down time and
joint changes.
Lt is also an aim of the present invention
to provide a rotating joint wherein the bolt which
joins the rotating flange to the non-rotating flange
is provided with a roller construction adapted to
bear against one of the flanges, and will thereon
upon a rotational relative displacement of the
flanges while maintaining the seal therebetween.
A construction in accordance with the
present invention comprises a rotating joint for
installing between first and second conduit means
which rotate relative one to the other. about an axis
of rotation. The rotating joint comprises first and
second parallel flange means extending radially about
the axis. The flange means are mounted to adjacent
ends of respective ones of the first and second
conduit means and face each other. At least one
arcuate slot means is defined in the first flange
means about the axis. At least one elongated member
extends through the first and second flange means and
is slidable in the arcuate slot means. A roller
means is rotatably mounted at least at a first end of
the elongated member outwards of the first flange
means and is adapted to bear thereagainst. A
retaining means is provided at a second end of the
elongated member outwards of the second flange means
to secure the first and second flange means together.
Therefore, upon relative rotational movement of the
pair of flange means about the axis, the elongated
member displaces relative to the slot means with the
roller means rolling on the first flange means while
maintaining a seal between the first and second
flange means.
In a more specific construction in
accordance with the present invention, the roller
means comprises two par allel rollers disposed on each
side of the slot means. The retaining means
comprises a nut engaged on and completely covers the
second end while bearing against the second flange
means.
In a still more specific construction in
accordance with the present invention, the tie rod
means has a cross-section within the arcuate slot
means which is substantially of rectangular shape.
In a still more specific construction in
accordance with the present invention, a pin means is
fixedly mounted at the first end of the tie rod means
and extends transversely thereto with a longitudinal
axis o:E the pin means extending parallel to a radius
of the flange means. The rollers are rotatably
mounted to the pin means.
In a still more specific construction in
accordance with the present invention, the first and
second flange means a.re respectively mounted to the
first and second conduit means. The first flange
means is stationary whereas the second flange means
is adapted to rotate with the second conduit means.
The tie rod means passes through the second flange
means through a hole defined therein which is smaller
than the nut.
In a still more specific construction in
accordance with the present invention, the slot means
has a length corresponding to a limited rotation
angle of the second flange means.
In a still more specific construction in
accordance with the present invention, more than one
of the slot means and of the hole are, respectively
defined in the first and second flange means. The
slot means are all similarly shaped. One tie rod
means, one nut and one pair of rollers are provided
for each corresponding hole and slot means.
In a still more specific construction in
accordance with the present invention, four equally
spaced slot means are distributed near a periphery of
the stationary first flange means.
In a still more specific construction in
accordance with the present invention, a ceramic seal
gasket is provided between the first and second
flange means.
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Tn another specific construction in
accordance with the present invention, the rotating
second Flange means is mounted to a tilting
metallurgical furnace, whereas the stationary first
flange means is mounted 'to a stationary launder means
adapted for conveying molten metal produced by the
furnace.
It is noted that Applicant's prior rotating
joints had a frequency of replacement of one or two
per week per tilting furnace. The first rotating
joints in accordance with the present invention
remain as efficient today as when they were installed
a few months ago and their failure is not anticipated
in the near future. These same rotating joints still
provide leak free and infiltration free seals between
the furnace and the launder. It is noted that each
previous joint change required approximately ten
manhours of work.
Having thus generally described the nature
of the invention, reference wilt now be made to the
accompanying drawings, showing by way of illustration
only a preferred embodiment thereof, and in which:
Fig. 1 is a top plan view of a tilting
furnace provided with a rotating joint in accordance
with the present invention;
Fig. 2 is a cross-sectional view taken
along lines 2-2 of Fig. 1 and showing a front view of
the rotating joint;
Fig. 3 is a cross-sectional view taken
along lines 3-3 of Fig. 2; and
Fig. 4 is a cross-sectional view taken
along lines 4-4 of Fig. 3.
Fig. 1 is a top plan view illustrating a
tilting metallurgical furnace F, a stationary launder
L, th at is a discharge conduit or trough for the
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molten metal produced by the furnace F, and a
rotating joint J in accordance with the present
invention provided therebetween.
The :Furnace F is mounted on bearings 24
with motor means which are not illustrated being
provided in order to cause the furnace F to rotate
along 'the direction shown by arrow 10 and about axis
12 so that the molten metal contained therein may be
discharged from the furnace F through a furnace
opening 14 defined by a cylindrical outlet pipe 16.
The molten metal is then fed through the rotating
joint J into the stationary launder L.
The rotating joint J includes a rotating
flange 18 and a stationary flange 20 and a ceramic
seal gasket 22 provided therebetween. The rotating
flange 18 is installed at the end of the outlet pipe
16 whexeas the stationary flange 20 is installed to
the launder L. The rotating joint J and the outlet
pipe 16 share an axis which is coaxial with the axis
12 of furnace tilt or rotation.
The flanges l8 and 20 are attached together
with four adjustable screws 26 with roller mountings
28. To receive these adjustable screws 26, the
rotating flange l8 defines a respective hole for each
one of the screws 26, whereas the stationary flange
20 defines arcuate slots 30, there being the same
number of arcuate slots 30 than 'there are adjustable
screws 26.
In the present preferred embodiment, there
are four adjustable screws 26 with roller mountings
28 and, thus there are also four equally spaced holes
defined in the rotating flange 18 and four equally
spaced similar arcuate slots 30 defined in the
stationary flange 20.
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The arcuate slots 30 are curved in order to
be coaxial with the rotating joint J and therefore
the tilt axis 7.2 of the furnace f. The arcuate slots
30 are of length equivalent to the angular
displacement or tilt of the furnace F.
Each adjustable screw 26 includes a tie rod
32 which passes through a respective one of the
arcuate slots 30 of the stationary flange 20, through
the ceramic seal gasket 22 and through a respective
one of the holes defined in the rotating flange 18.
The portion of the tie rod 32 which coincides with
the arcuate slot 30 of the stationary flange 20 has a
generally rectangular cross-section for reasons which
will be presented hereinafter.
A first end 34 of the tie rod 32 is
threaded for receiving thereon a nut 36 which is
adapted to cover completely the portion of threaded
end 34 which extends beyond the rotating flange 18 in
order, for instance, that molten metal does not
accumulate on the threads and damage the same. The
nut 36 is provided with a pair of perpendicular
diametrical apertures 37 which are used to tighten
the nut 36 by way of a rod (not shown) passed
therethrough. The nut 36 is large enough to ensure
proper pressure and solid contact on the rotating
flange 18. A second end 38 of the tie rod 32 has the
shape of a short cylinder transversely mounted in a
fixed relationship to the tie rod 32 so that the
cylindrical end 38 has its axis a-t right angles to
the axis of the tie rod 32. A pin 40 extends
centrally through the cylindrical second end 38 of
the tie rod 32 and is fixedly secured thereto by way
of a mounting pin 41 extending transversely through
the second end 38 and the pin 40.
The roller mountings 28 include a pair of
rollers 42 rotatably mounted to the pin 40 on each
side of the cylindrical second end 38 of the tie rod
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32 and maintained to the pin 40 by a pair of snap
rings 44. The thickness of the cylindrical second
end 38 is substantially equal to the width of the
arcuate slots 30 in order that the cylinder-shaped
rollers 42 can be positioned to bear against the
stationary .flange 20 on each side of a respective one
of the arcuate slots 3U thereof.
The flanges 18 and 20 are secured one to
the other with the ceramic seal gasket 22
therebetween by passing the threaded first end 34 of
the tie rod 32 through the arcuate slot 30 of the
stationary flange 20 and then through the seal gasket
22 and the corresponding hole defined in the zotat:ing
flange 18. The pin 40 of the adjustable screws 26
are then positioned parallel to a radius of the
flange 20 in order that the rollers 42 will bear
against the stationary flange 20 on each side of the
arcuate slot 30 thereof when the nut 36 is engaged on
the threaded part of the threaded first end 34 of the
tie rod and tightened against the rotating flange 18.
The rectangular portion of the tie rod 32 located
within the arcuate slot 30 of the stationary flange
20 prevents the tie rod 32 from rotating with respect
to the stationary flange 20 and thus ensures that the
axis of rollers 42 remains parallel to the flange
radius and that the rollers 42 remain parallel to the
rotating movement.
From the above, it is readily understood
that a tilting motion of the furnace F will cause the
outlet pipe 16 to rotate therewith and 'thus also the
rotating flange 18 to rotate thereby causing the tie
rods 32 to displace along the arcuate slots 30 and
the rollers 42 to rotate about the pin 40 while
rolling on the stationary flange 20. This allows a
free motion of the furnace tilt while keeping a
constant pressure on the flanges 18 and 20, The
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ceramic seal gasket 22 used in between of the flanges
18 and 20 has high insulating properties and can be
compressed.
Hence, the novelty resides in the
substitution of the rollers 42 to bear against the
outer stationary flange 20 of the rotating joint J
around the molten metal pour central opening of the
joint J while the .furnace F is being tilted in place
of a nut such as the nut 36 which bears against the
inner rotating flange 18 of the rotating joint J.
The rollers 42 ensure a durable and efficient seal to
the rotating joint J.
From the above, it is easily understood
that the arcuate slots could be defined on the inner
rotating flange while holes would be defined on the
outer stationary flange as long as the rollers are
positioned to roll against the inner rotating flange
and thus on each side of the arcuate slots. In such
a case, the tie rods would remain stationary with the
outer stationary flange while the arcuate slots of
the inner rotating. flange would displace therewith
thereby causing the rollers to rotate about
stationary axes.
A various number of arcuate slots may be
provided as well as slots of different length in
order to accommodate various relative tilting angles
between the flanges.
The above innovative rotating joint J has
been installed in Applicant"s plant and has provided
the assurance of a reliable seal against infiltration
and leaking while molten metal flows through the
joint. The rotating joint provides a practically
maintenance free unit which has therefore resolved
problems associated with down time and joint changes.
Again, the previous joint had a frequency of change
of one or two per week per tilting furnace whereas
the above new rotating joint has maintained a same
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efficiency a few months after its installation. It
has been observed that the rollers make a
surprisingly big difference in mainte>nance costs.
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