Note: Descriptions are shown in the official language in which they were submitted.
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A COOLING ROLL
This invention relates to a roll suitable for
transferring heat between the roll and the material in
contact with it. A particular, but not sole, application of
the invention is to a roll suitable for use in a two-roll
strip caster.
A strip caster usually consists of a pair of
rolls, arranged side-by-side with their axes of rotation
horizontal, and which are spaced apart to provide a gap
between them. On the upper side of the rolls, the ends of
the roll barrels can be provided with dams to form a space
above the roll gap into which molten metal is poured. The
rolls are usually liquid cooled to absorb heat from the
molten metal which come into contact with them and form
solidi~ied skins which thicken as the rolls rotate. As the
rolls are rotated they ~orce the solidi~led skins o~ metal
together and through the gap between the rolls to form a
continuous metal strip.
In an effort to increase casting output, it is
desirable to increase the speed of rotation o~ the rolls,
but care has to be taken that the rolls absorb su~ficient
heat from the metal in contact with them to form two
solidified skins whose total thickness is greater than the
end product.
US-A-4019846 discloses a roll employed in a
briquetting machine. The roll comprises an arbor with an
annular sleeve mounted on the arbor. There are axially
extending passageways for cooling liquid in the sleeve and
manifold ring assemblies mounted externally of the roll
enable the cooIing liquid to be supplied to the passageways.
Two rings mounted externally of the roll are connected to
opposite sides of the arbor and sleeve th¢reby preventing
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relative movement between them.
DE-A-3839110 discloses a roll for a twin-roll
continuous caster. The roll comprises an arbor on the
circumference of which are first and second sleeves. The
first sleeve is a shrink fit on the arbor and the second
sleeve is a shrink fit on the outer periphery of the first
sleeve. Cooling liquid is supplied to the interface between
the two sleeves and passes in the axial direction of the
roll along the interface.
An object of the present invention is to provide
an improved roll construction which permits
greater throughput together with a stable roll design, which
can readily be refurbished at the end of its
useful life.
According to the present invention a cooling roll
comprises a rotatable arbor; an annular sleeve structure
mounted on the arbor with a shrink fit interface between
the outer peripheral surface of the arbor and the inner
surface of the annular sleeve structure; said sleeve
structure having internal passages for the flow of liquid
coolant therethrough; ducts in the arbor in communication
with the internal passages whereby, in use, liquid coolant
flows through the ducts and the passages to form an annular
thermal barrier in the sleeve structure; characterised in
that the sleeve structure comprises either a single annular
sleeve or inner and outer sleeves joined together without a
shrink fit interface between them.
The sleeve structure may be provided with a
plurality of internal passages each extending paralLel to
the longitudinal axis of the arbor. These passages may be
formed by boring holes along the axis of the sleeve.
Alternatively, there may be a plurality of
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internal passages extending around the sleeve structure and
coaxial with the periphery thereof.
In order to absorb as much heat as possible from
the molten material, it is necessary for the part of the
roll which contacts the molten material to be of a high
conductivity metal, such as steel, copper, or any of their
alloys.
The surface of the high conductivity metal may be
covered with a protective surface layer, which for example
could be a stainless steel with good thermal fatigue
properties or a nickel or nickel/chrome layer or a metal
matrix composite layer such as tungsten carbide/cobalt alloy
or chrome carbide/nickel-chrome composite.
At the end of its useful life the 51eeve structure
may be removed from the arbor by externally heating to
expand the sleeve structure whilst omitting all cooling.
The sleeve structure could then be re~urbished
prior to re-assembly.
The sleeve structure serVes as the roll barrel
and, since an external force can be exerted upon it, there
has to be a shrink fit between the sleeve and the arbor to
prevent it rotating around the arbor.
In use, care has to be taken that the temperature
of the sleeve structure relative to that o~ the arbor is not
such that will cause differential expansion between the
arbor and the sleeve structure so as to remove the interface
joint between them. By arranging for a thermal barrier to
be located between the outer surface of the sleeve
structure and the i~te~face between-&le~ve structur~ and the
arbor, a limited mini~um amount of the heat applied to the
outer surface of the sle~ve structure penetrates to the
interface between the sleeve and the arbor. At the same
time, the liguid cooled sleeve structure efficiently removes
heat ~rom the outer sur~ace of the sleeve structure thereby
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permitting rapid cooling of the material which iq in contact
with it.
~ he interference fit betwesn the sleeve structure
and the arbor provides a tensile stress in the sleeve
structure which helps to negate the thermally induced
compressive stresses.
In order that the invention may be more readily
understood, it will now be described, by way of example
only, with reference to the accompany drawings, in which:-
Figure 1 i5 a view, partly in sect~on, of acooling roll in accordance with the present invention;
Figure 2 shows to an enlarged scale the part o~
the roll within the broken lines of Figure l; and
Figure 3 shows a sectional view o~ an alternative
cooling roll also in accordance with the invention.
A roll suitable for use in a metal caster
comprises an elongate arbor 1 having cylindrical portions 3
ad~acent each end ~or receiving bearing assemblies (not
shown). Substantially at the centre of the arbor there is a
cylindrical sur~ace 5 on to which an annular copper-alloy
sleeve stxucture 7 is shrunk. At one end of the surface 5
there is an annular rib 9 which i8 integral with the arbor.
An annular recess 10 is formed in the adjacent end wall 11
of the sleeve and a plurality of fitted bolts (not shown)
extend through the rib into the sleeve 11 to provide
additional securement for the sleeve on to the arbor. The
recess 10 is closed off by an annular ring 12 which is
secured to the rib 9 by a plurality of bolts 13.
An -ax-ial-- bore- i5 ex~ends-- into t~e arbor 1 from
the non-drive end 16. A pair of annular channels 17A,
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17B are formed in the surface 5 of the arbor beneath the
sleeve 7. A plurality of radial bores 19 extend from
the channel 17A to the bore lS and, similarly, a
plurality of radial bores 21 extend from the channel 17B
to 1:he bore 15. In the end face 11 of the sleeve 7,
there is an annular channel 22 and a similar channel 23
is formed in the end wall of the opposite end of the
sleeve. The two channels 22, 23 are connected by a
multiplicity of passages 25 which extend between them in
a direction substantially parallel to the longitudinal
axis of the arbor 1. The passages 25 are spaced apart
around the entire annular sleeue. In addition, the
channel 22 is connected to the channel 17B by a bore 27
within the sleeve and, similarly, the channel 23 is
connected to the channel 17A by an internal bore 28.
The channels 22, 23 are closed o~f by cover plates 29
which may be of the same material as the sleeve 7 and
fixed in position by any convenient means such as
welding along lines 30.
A tube 34 with a central enlarged outer
diameter and seal 35 is located within bore 15 and
provides a barrier between two annular areas 17A and 17B
one of which communicates with radial bores 19 and the
other communicates with radial bores 21 for the passage
of outgoing and incoming liquid coolant.
In use, liquid coolant, usually water, is
passed along the space between the tube 34 the bore 15
and into each of the bores 19 where it flows to the
channel 17A at the interface between the sleeve and the
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arbor. The water then flows along the bore 28 to the
channel 23 extending around the adjacent end face of the
sleeve.
From this channel, the water floYs through the
mu1tiplicity of bores 25 to the channel 22 in the end
face 11 of the sleeve.
T~e water flowing through the passageways 25
cools the adjacent parts of the sleeve and,
consequently, a cooled zone extends around the sleeve in
the vicinity of the passageways. This cooled zone
serves as a barrier which reduces the flow of heat from
the outer surface of the sleeve to the interface between
the sleeve and the arbor, thus preventing the
temperature of the sleeve in the vicinity of the
interface with the arbor from rising to a level where
the shrink fit interface between the sleeve and the
arbor is destroyed. The cooled zone serves to cool the
outer surface of the sleeve thereby causing metal to
solidify in contact ~ith the surface.
From the channel 22 the water flows along the
bore 27 to the annular channel 17B and then via the
bores 21 to the annulus formed by the pipe and bore 15
on the opposite side of the seal 35 and through the tube
34. The coolant may be made to flow in the reverse
route to that described previously. A rotary coupling
(not shown) is coupled to the end 16 of the ar~or to
permit coolant to circulate through the roll as the roll
is rotated.
An annular seal 33 is located at each end of
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and between the sleeve and the arbor to prevent leakage of
coolant from between the arbor and the sleeve. These seals
can be fitted after assembly of the sleeve which will aid
~aintenance in the event o~ failure as vell as negate the
requirement to assemble the seals prior to the shrink
fitting of the sleeve 7 on to the arbor 1.
The sleeve can have a hard facing layex 31 on its
outer periphery. This layer may comprise of chrome on
nickel or stainless steel or a metal matrix composite such
as tungsten carbide/cobalt alloy or chrome carbide/nickel-
chrome composite. The barrel ends of sleeve 7 also can have
similar hard facing layer 32.
Figure 3 shows sleeve structuxe 35 formed by
welding or otherwise suitably joining together two separate
sleeves 35a, 35b at joints 36. Coolant enters the arbor 38
along a hole 39 and then passes via radial bores 40 to a
slot 41 at the shrink fit interface bet~een the sleeve
structure and the arbor.
From ~lot 41, the cooling water passes through a
series of radial holes 42 to circumferential grooves 43 at
the interface between the two sleeves where it splits into
two directions to pass circumferentially around the sleeve
structure until the two flows unite to exit by a second
series of radial holes 44. The cooling water passes from
radial holes 44 to a second slot 45 which is connected to
the outlet hole 46 in the arbor 38 by radial bores 47.
Figure 3 also shows an alternative method of
providing the rib 9 shown in Figures 1 and 2. The rib is
formed by ~ixing-a-disc 48-to_the arbor 38 wi-~ bolts 49.
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