Note: Descriptions are shown in the official language in which they were submitted.
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10-84~ Continuous Castinq ~p~aratus
~nd~
Technical Field
The present invention relates generally to contin-
uous casting processes and in particular to a method
and apparatus for continuously casting relatively thin
strip, both outer surfaces of which, have been cast
against a chill surface.
Backaround Art
Various apparatus and methods or continuously
casting two sided metal strip utilizing opposed moving
chilled surfaces, are known or have been suggestecl in
the past. In such instances, two confronting, moving
surfaces are employed. In a "Bessemer" machine (U.S.
Patent No. 49053), a pair of confronting but spaced
apart rolls define the moving surfacesr The axes of
the rolls are typically parallel and horizontally posi-
tioned and the roll surfaces form a nip where the rolls
are closest to each other which defines the casting
thickness. Molten metal contained between upper
portions of the roll and side dams above the nip,
freezes on the chilled periphery of the rolls.
In theory~ a continuous solidified strip of metal
is discharged vertically downward from the nip of the
rolls. It has been found, however, that the process of
using rolls and side dams for containing the pool can
be very difficult to control. In particular, in the
fixed gap mode of operation, (i.e., where the roll
center to center distance is fixed) if sufficient
contact time is not provided between the metal being
solidiied and the chilled surfaces, "break out" can
occur in which molten metal in the center of the strip
ruptures through the hardened outer layer. If the
contact time is excessive, the rolls may jam because the
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2 ~2~ 3'?
total thickness of material solidified on each of the
rolls is greater than the nip dimension. In addition,
free2ing of material on the side dams causes jams and/or
other process problems.
The Bessemer-type machine is considered a "conver-
ging gap" type machine (as opposed to a "constant gap"
machine) since the pool of molten metal carried above
the confronting rolls has a transverse dimension that
decreases as the nip is approached. In a Bessemer
machine the contact time is determined by the dimension
of the rolls and their speed and the pool depth.
In an effort to overcome some of the difficulties
of the Bessemer machine, an "inside-the-ring" (ITR)
type machine has been suggested in the past in which a
large rotating vertical ring contains a pool of molten
metal at the bottom. As the ring rotates, molten metal
freezes on an inside surface to form a strip of material
that is discharged spirally from the ring. The ring
normally has cooled metal side dams which contain the
pool of molten metal. To make the process two-sided, a
roll or drum is rotatable with the ring and defines a
gap or nip between itself and the inside of the ring.
An example of such an apparatus is shown and descxibed
in U.S. Patent No. 3,773,102. In this type of machine,
"ear loss" that is, the material which is cast against
the side dams and must later be trimmed becomes a
concern. It should be appreciated that molten metal
freezes on any chilled surface and in the case of an
"ITR" machine, material can be expected to solidify on
the side dams and the sides of the drum. Generally the
"ears" can be cut from the strip and rP-used as scrap
metal.
Constant gap strip casting machines ~such as the
Hazelett twin belt machine which is well known in the
industry) do not in general have an ear problem in that
3 ~ 3 ~
they cast strip of a rectangular rather than a channel
-shaped cross-section. In the typical constant gap
machine liquid metal fills the gap at the input end of
the machine and as the metal moves down the machine and
freezing progresses from the walls, the central core of
liquid metal gradually decreases from the full thickness
of the constant gap to zero. Such machines use constant
thickness blocking means to keep the :Liquid from running
out at the ends; such blocks may run along with the
moving casting surfaces.
5enerally the most serious problem encountered
with constant gap machines is providing a means for
introducing the molten metal into the casting gap.
Since in all constant gap machines, a gap corresponding
to the final casting thickness is defined between the
two casting surfaces, for small thickness strip
material, verv little access is provided for introducing
molten metal.
Several methods have been used for preventing the
metal from running out at the ends in converging gap
machines. Although attempts have been made to contain
the metal with insulators which are supposed to operate
at a high temperature so that no metal is cast against
them, the general method of interest here involves
containing the converging gap with casting surfaces.
Two such methods are exemplified by the inside-the-ring
machine (U.S. Pat. No. 3,773,102) and the Schloemann
drum-belt machine (U.S.Pat. No. 3,627,025). In both of
these a pool of metal is restrained at the sides by
metal (or coated metal) side dams which preferably move
contiguously with the ring or belt of the machine. In
the Schloemann machine, the ears are straight up (i.e.
at right angles to the strip). In the ITR machine the
ears project upward at some greater angle than 90~ to
the strip. However, in both of these machines, a gap is
~ 3 ~ ~ ~ 3 r~
provided between the end of the drum and the rlng side
dam. This gap must be at least wide enough to accom-
modate the thickness of metal that is frozen on the
drum ends and on the side dams. This gap is typically
open ended at the top.
Another machine utilizing cast in ears as an edge
restraint is seen in U.S. Pat. No. 2,450,428 (Hazelett)
and features a drum with rounded ends proximate to and
forming a nip with either the outside or the inside of
a large ring that is fitted with side dams which cast
ears of arcuate shape. Here the ears are arcuate and
taper to zero thickness at the top. It is noted that
the side dams of the ring each touch the adjacent
rounded end of the drum at essentially only one point.
This point is a point of tangency of a circle on the
drum and another circle on the ring.
In all of the converging gap desiyns cited above,
the depth of the pool is at most the height of the side
dam of the r-ng, and in the case of the Hazelett roll
outside the ring machine it is less.
Another important consideration is the productivity
of a given machine. As indicated above, the speed at
which a machine can produce a solidified strip is a
function of "contact length" of the molten metal with
the chilled surface or surfaces. It is well known from
actual experiments that the thickness of casting that
builds up against a chill surface varies at least
approximately according to the relation
x = K ~ -B where
x = inches of casting thickness
t = seconds of immersion time
X and B are constants depending on the parameters
of the system (materials, temperatures, etc.)
It follows that if a given thickness is to be cast,
a certain immersion time is required to cast it. This
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time may be realized for example by either a short
immersion length in a slowly moving machin~ or a long
immersion length in a fast moving machine. Obviously
machines with long immersion lengths are faster and more
productive, and an otherwise small machine with a long
immersion length is to be preferred from a first cost
and a productivity standpoint.
For converging gap machines with appreciable
contact time, the formation of ears blecomes a serious
problem. It should be appreciated that the increased
contact time which allows a greater productivity of
strip also increases the time during which the ears can
be formed and hence greater ear thickness may result.
In all inside the ring or belt machines of converging
gap design where an open pool is employed (e.g. the ITR
or the Schloemann machines), the ear height is at least
as great as the depth of the open pool.
Disclosure of the Invention
The present invention provides a new and improved
method and apparatus for continuously casting metal
strip in which high productivity can be realized with
reduced ear loss. In the preferred and illustrated
embodiment, a machine having the advantages of extended
contact time, converging gap, and metal rather than
refractory side dams etc. is provided.
According to the invention, two converging casting
surfaces are defined into which molten casting material
is introduced. Edge constraints usually termed "side
dams" contain the casting material between the converg-
ing casting surfaces. According to the invention, theedge constraints are configured to accommodate the
growth of "ears" along the edge of the metal strip as it
moves through the casting arc or casting path. As is
known, the size of the ears increase as the cast strip
approaches the end of the casting path. With the
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present invention, the side dams are configured to
accommodate the increasing size of the ears so that
interference, or so called "ear crushing" does not occur
at the exit nip or end gap defined by the casting
surfaces.
In one embodiment of the invention, a belt and
drum together define non-concentric, circular casting
surfaces and in effect form a converging gap. Side
dams in association with the belt move about an axis of
rotation that is different from the axis of rotation of
the drum. In addition, the side dams or cheeks define
a recess for receiving ear material as it is formed.
The recess defined between the cheek and a side of the
drum increases in the radial direction as the end of
the casting arc is approached.
The side of the drum is vertical and at right
angles to the cylindrical drum surface. During one mode
of operation, material is cast on the side of the drum
as well as the cheek. The expanding recess provides a
2Q relief for this material so that jamming does not occur
at the point where the belt and drum are closest.
According to a feature of this embodiment, the
cheeks are defined as the inner surfaces of a pair of
rings rotatable about an axis that is off-set from an
axis of rotation of the drum. A recess is formed on an
inside radial face of each ring member such that the
recess, narrowing in the direction of decreasing radius,
is defined between confronting portions of the drum
(i.e. the vertical sides of the drum) and the cheek
ring. Each ring also defines a circumferential surface
against which an endless belt rides for a portion of
its travel. A converging casting gap is thus defined
between a casting surface on the drum surface and an
inside belt surface, the variable distance at which the
belt is spaced from the drum being determined by the
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ring members and their eccentricity with the drum. In
the preferred and illustrated embodiment, the radi.us of
rotation for the belt when in contact with the cheek
members is selected to be larger than the radius of the
drum, the difference in the radii being equal to the
eccentricity between the rings and drum plus the thick-
ness of strip being cast. With the disclosed construc-
tion, a converging gap machine can be realized in which
extensive contact length is provided while controlling
or reducing ear loss.
According to another feature of the invention, the
cheek members are biased by springs or other forces
towards a side surface of the drum to inhibit leakage
of molten material between the cheek and the side of
the drum. In the preferred emhodiment, a frame member
mounts a bearing arrangement which in effect defines a
fixed, non-rotatable bearing race that captures ball
bearings which in turn rollingly support the cheek
member. The cheek member includes surfaces defining a
cooperating, bearing race. In the preferred and
illustrated embodiment, driving arrangements are
provided for driving the drum at a predetermined speed
as well as driving the belt and ring members. Preferab-
ly, the ring members and belt are driven at constant
speed so that the belt and cheeks move in unison. To
compensate for the greater distance that must be
traveled by the belt since its radius of movement is
larger than the drum, the belt and cheeks may be driven
at a somewhat greater surface speed than the drum for
reasons that are described in U.S. patent No. 3,811,491.
In another embodiment of the invention, a drum
rotating within a rotating ring define non-concentric,
circular casting surfaces which together form a
converging gap. This is often termed an "in-the-ring"
c~
or ITR type machine. In this embodiment, an oscillating
cheek, defining a tapered recess, is used on both sides
of the machine to constrain the molten pool in the
casting arc. As in the first embodiment, an expanding,
ear receiving recess is defined between a cheek and its
associated side of the drum. In operation, material is
cast on the side of the drum as well as the associated
cheek. The recess expands tin the radial direction) as
the end of the casting arc is approached and provides a
relief for the cheek material so jamming does not occur
at the point where the drum and ring are closest.
In another embodiment, the principles of the
invention are applied to a Bessemer type machine in
which the casting surfaces are defined by tWQ spaced
apart rolls. In this embodiment, the edge constraints
(for containing the molten pool) are defined a pair of
belts disposed on each side of the rolls and which in
effect, defined an expanding recess associated with each
roll. It should be notPd that in the above two
described embodiments, the cast strip was substantially
U-shaped in cross section with the ears defining the
legs of the U-shaped section. In the Bessemer type
embodiment, the cast strip resembles an I-Beam in cross
section since an expanding recess is defined for each
drum side and there are four sides. In this embodiment,
the belts are substantially vertical oriented and travel
in substantial synchronization with the strip material
as it is being cast. The belt pairs are arranged at an
angle with respect to their associated roll sides and
thereby define tapered recesses. The juncture of the
belts define the center line of the cast strip.
In still another embodiment, the principle of the
invention is applied to a converging belt type machine.
In this embodiment, ear receiving recesses are defined
by a belt of cheek blocks that travel along the edges of
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the belts. In the preferred construction, one belt is
vertically oriented whereas the other belt rides along a
curved guide in a confronting relationship with the
first belt to define the converging gap. The belt of
blocks abuttably contacts the surface of the vertical
belt and the side of the curved guide. In effect, the
belt of blocks (when in contact with he casting belts)
defines an expanding recess between 1:he inside of the
confronting blocks and the side of the casting belt
guide that expands as the end of the casting arc is
approached. In this embodiment of the invention, the
resulting metal strip is substantially U-shaped in cross
section with the legs of the "U" defined by tapered
ears.
In general, th~ various casting members and
components of all of the embodiments are water cooled by
various known techniques.
Additional features of the invention will become
apparent and a fuller understanding obtained by reading
the following detailed description made in connection
with the accompanying drawings.
Brief Description of the Drawinq~
Figure l is a schematic representation of an
apparatus embodying the present invention;
Figure 2 is a fragmentary, sectional view of the
apparatus shown in Figure l as seen from the plane indi-
cated by the line 2-2 in Figure l;
Figure 3 is a fragmentary, sectional view as seen
from the plane indicated by the line 3-3 in Figure l;
Figure 4 is a fragmentary, sectional view as seen
from the plane indicated by the line 4-4 in Figure l;
Figure 5 is a side elevational view of a casting
machine embodying the present invention;
Figure 6 is a fragmentary vertical sectional view
lo ~ `? ~ CJ~ ~
of the machine as seen from the plane indicated by the
line 6-6 in Figure 5;
Figure 7 is a fragmentary view of the machine shown
in Figure 5 with parts omitted for clarity; and,
Figure 8 is a top elevational view of the machine
shown in Figure 5;
Figure 9 is a side elevational v:iew of a belt
adjusting mechanism;
Figure 10 is a top plan view of a Bessemer-type
embodiment of the present invention, shown somewhat
schematically;
Figure 11 is a side-elevational view of the
apparatus shown in Figure 10;
Figure 12 is a view of the cast strip as seen from
the plane indicated by the lines 12-12 in Figure 11;
Figure 13 is a side elevational view of another
embodiment of the invention as applied to a converging
belt type machine, shown somewhat schematically;
Figure 14 is a sectional view as seen from the
plane indicated by the line 14-14 in ~igure 13;
Figure 15 is another sectional vi~w as seen from
the plane 15-15 in Figure 14;
Figure 15a is an enlarged, fragmentary view of a
belt of cheek blocks forming part of the embodimnet
shown in Figure 13;
Figure 16 is another sectional view as seen from
the plane indicated by the lines 16-16 in Figure 14;
Figure 17 is a side e~evational view of another
embodiment of the invention as applied to an in-the-ring
type machine, shown somewhat schematically;
Figure 18 is a sectional view as seen from the
plane indicated by the line 18-18 in Figure 17; and,
Figure 19 is another sectional view as seen from
the plane indicated by the line 19-19 in Figure 17.
Best Mode for Carryinq Out the Invention
` ~2~ J~7~
Figure 1 schematically illustrates an apparatus
constructed in accordance with a preferr~d embodiment
of the invention. The apparatus includes a casting
drum 10 rotatable about an axis 12. A belt 14 supported
between rolls 16, 18 moves below the drum 10 in a spaced
relationship, the distance between a drum surface lOa
and an inner belt surface 14a decreasing such that a
converging gap, indicated generally by the reference
character 20 is defined.
Rotatable side cheeks 22 (only one cheek is shown
in Figure 1) are disposed on either side of the drum 10
and each cheek defines a peripheral, circumferential
surface 22a against which the belt 14 is supported as
the belt moves below the drum 10. Each cheek member is
preferably annular or ring-like in construction7 An
axis 26 sf rotation for the cheek members ~2 is spaced
from the axis of rotation 12 of the drum. The radial
distance between the peripheral surface 22a and the
axis of rotation 26 is larger than the radius of the
casting surfac lOa of the drum 10. The cheeks 22 are
supported for rotation by bearings 28, shown schemati-
cally.
Molten metal is injected or delivered into the gap
20 by a nozzle 30 so as to fill the pool to the level
L. In operation, as the drum 10 and cheeks 22 rotate in
the counterclockwise rotation (as viewed in Figure 1)
molten metal freezes on the belt surface 14a and drum
surface lOa since these surfaces are normally chilled.
These partial strips are indicated by the reference
characters 32, 34. As expected, the thickness of the
strips gradually increase as the contact time in-
creases, i.e., as the chilled surfaces move towards the
end of the casting arc. At or near the end of the
casting arc indicated by the reference character 38, the
individually cast strip portions 32, 34 fuse together
~ 3~ ~ ~?2
and exit the casting arc as a unified strip of material
indicated generally by the reference character 40. The
cast strip 40 then proceeds through an additional arc of
travel maintaining contact with the belt until the belt
is stripped from the casting when it changes curvature
by being payed onto roll 18. To ensure this action, a
very slight overspeeding of the drum may be employed.
The apparatus shown in Figure 1 may include a
cutter assembly indicated generally by the reference
character 42 which is operative to trim the "ears" from
either side of the strip as the strip exits the
machine. The cutter is preferably positioned so that
the ears are cut off before the casting is bent to a
different radius of curvature from that shown at 40.
Referring also to Figures 2-4, the construction of
the cheek members 22 and their cooperation with the
drum 10 will now be explained. Figures 2-4 represent
sectional views of the apparatus as one proceeds along
the casting arc. In Figure 2I the distance between the
belt 14 and periphery of the drum 10 is relatively large
and facilitates the introduction of molten metal by the
nozzle 30. As seen in these Figures, each cheek member
22 defines an inner tapered surfa~e 44 such that in
section, the transverse dimension of the cheek member
narrows with a radially increasing distance. Each cheek
member also defines a short, radial abutting surface 46
which slidingly and sealingly engages a side of the
drum 48 in order to define a closed ear cavity or recess
50 when the cheeks move through the casting arc 20. The
width of the cavity 50 between the cheek and the drum
as shown in Figure 4 increases with increasing radial
distance.
The ring cheek construction as described represents
a novel way of edge containment in a casting machine in
that the ear cavity is closed (and slidably sealed) at
~ ~ 2 ~
13
the top for a considerable length, thus permitting a
liquid metal pool to exist which is of considerably
greater depth than the height of the ears cast by the
machine. The height of the ears is essentially the
width of the open pool surface into which liquid metal
is poured and (insofar as the dimensions and design of
the metal input means, e.g., nozzle, can be minimized)
this dimension and hence the ear loss can be minimized.
However, even with this width so minimized, this design
affords an adequate width of pool many times the thick-
ness dimension of the strip being cast.
It is recognized that the shape of the recess in
the cheek may be varied for best results - generally to
~ provide a just-sufficient space for the ear during its
formation without allowing the ear thickness to encroach
on the space between the curved face of the drum and
the belt while still keeping to near zero the amount of
liquid that flows around to the flat side of the drum.
Obviously some amount of shearing and/or tearing of
just-solidified ear material may occur. Since the ears
are removed and remelted, their quality does not matter.
As described above, the centers of rotation for
the cheek members and drum are different. They are
selected such that, for the portion of rotation through
the casting arc, each cheek member moves radially
inwardly with respect to the drum. This relationship
can be seen in Figures 3 and 4 where it should be noted
that the distance between the drum surface 10a and the
inner belt surface 14a decreases substantially. As seen
in Figures 3 and 4I since the cheek member 22 defines a
tapering surface 44, a gradually increasing recess 50
is defined between the drum and the cheek member. The
recess 50 receives just cast ear material as the strip
approaches the nip 38.
~ 3 ';~
14
It must be remembered that material will freeze on
any chilled, uninsulated, or unheated surface. Each
cheek member 22 and the sides 48 of the drum each con-
stitute a chilled surface. Even though these surfaces
may, by design, be coated with insulating material to
mollify the rate of free2ing that will occur thereon,
it is recognized that some freezing will certainly
occur. As a result, during the casting process, material
will freeze on the drum surface lOa, belt surface 14a,
the portion of the drum side 48 that confronts the
surface 44 on the cheek and the cheek surface 44. As
the strip is formed, the thickness will increase as it
approaches the casting nip 38. This is illustrated by
the strips 32, 34 shown in Figure 4. If the cavity 50
is sufficiently wide in the axial direction, material of
comparable thickness will also form on the drum surface
48 and the cheeX surface 44. Because of the tapering
recess 50 that has an increasing transverse dimension,
this increasing ear thickness is accommodated. Hence,
with the present invention, jamming does not occur due
to ear formation.
In addition, under carefully controlled conditions,
and in general for a lower speed than for operating
under the conditions cited above, the ear formed on the
cheek surface 44 can mask the portion of the drum side
48 enclosed by the cheek member and, in effect, prevent
the freezing of material on the side of the drum. Under
these optimum conditions, substantially reduced ear
loss can be obtained.
However, if the operating speed chosen for a
machine with a given ear cavity is too low, the machine
will jam because more material will freeze on the cheek
surfaces than the cavity between the cheek and the flat
side of the drum can accommodate: the too-thick material
than grows out into the space between the curved surface
i
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of the drum and the belt where it is squashed and tends
to lift the drum.
It is seen that although a preflerred embodiment
features ~ drum that is spring or weight loaded against
the belt (floating drum), that an optional method of
operation is to fix the drum (constant nip dimension).
Turning now to Figures 5-8, a machine embodying
the present invention is detailed. ~omponents in
Figures 5-8 which have similar counterparts in Figures
l-4 will be designated with the same reference character
followed by an apostroph (').
Referring first to Figures 5 and 7, the belt
supporting apparatus and casting drum are best il-
lustrated. A first belt support roll 100 is supported
on a tail shaft 102. ~he casting belt 14' is reeved
under the casting drum 10' and cheek assembly, and is
reeved around a drive roll 104 supported for rotation by
a head shaft 106. The drive roll 104 is power driven by
a motor 108 ~shown in Figure 8) via a differential
assembly 109 (also shown in Figure 8). The lower
section of the belt 14' is supported by an idler roll
110 (shown in Figure 5) which includes an adjustment
mechanism indicated yenerally by the reference character
112 for adjusting the tension and/or tracking of the
belt 14'.
As seen best in Figure 7, a plurality of support
roll assemblies defining an upwardly spring loaded
roller apron 116 defines a circular path below the
casting drum 10' and provides support for the belt 14'
in the casting arc. Water conduits 12Oa, 12Ob are
provided and include a water inlet and header 122 for
feeding cooling water onto the belt between the fins
226 of the finned belt rolls 100, 104, respectively.
A doctor blade 130 is positioned above the casting
drum 10' and is located between a pair of cheek members
!
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16
22', 22a', 22b' (shown best in Figure 6). The doctor
blade includes a leading, angled blacle portion 130a
that guides any wayward leading edge of the strip
leaving the casting drum 10' into the cutter assembly
42'. The cutter assembly 42' includes a pair o~ upper
and lower cutters 132, 134 at either edge of the strip
so that ears formed on the strip can be trimmed as the
strip leaves the machine.
It will be evident to those ski:Lled in the art
that the trimming of the ears however done is most
desirably done before the strip is unbent from the.
radius at which it is cast. The inner edge (the smaller
radius) of the ears so trimmed are preferably con--
tinuously bent up by a scraper arrangement (not shown)
so that the trimmed ear exits the machine in a con-
tinuous spiral helix (in a manner completely analogous
to the spiral helix form of continuous chip generated by
a lathe tool in turning down a shaft). These continuous
spirals may be broken up by appropriate means.
As seen in Figure 7, the axis of rotation for the
cheek members 22' is indicated by the reference charac-
ter 140. The axis of rotation of the drum 10' is indi-
cated by the referenc2 character 144 and is defined by
a movable support system including bearing assemblies
146 (only one is shown in ~igure 5) which form part of
a yoke assembly 148. The yoke assembly 148 is movable
and is used to adjust the desired casting thickness or
alternately the drum pressure should a floating drum
operation be used. In the latter case the yoke assembly
148 may be spring loaded to adjust this pressure or to
allow the drum and belt to separate should the strip
thickness increase unexpectedly. In the disclosed
embodiment the illustrated yoke assembly 148 is spring
loaded by an adjustable spring assembly 150 to be
described further on.
17
Referring again to Figures 5 and 6, the supporting
frame for the various rolls and casting drum is
detailed. In particular, the frame comprises a pair of
upstanding supports 160, 162 which extend upwardly from
the floor or other rigid base. Transversely extending
cross members 164 (only one cross member is shown)
extend hetween and are supported by the upstanding
supports 160, 162. A pair of pillow blocks 16~ are
rigidly ~ixed at the upper end of the frame support 160
and to a cantilevered bracket therefrom and rotatably
support the tail shaft 102. Similarly, and as best
shown in Figure 8, the head shaft 300 is rotatably
supported by a pair of pillow blocks 170 bolted to the
upper ends of the upstanding support 162 and to a
cantilevered bracket therefrom. Supports 160, 162 occur
only on the near side of the belt in Figure 5 and the
frame structure for supporting far side pillow blocks
166, 170 is cantilevered out (away from the viewer) from
these supports so that belt replacement from the far
side is facilitated.
The cheek suppor' assemblies and associated
components are supported by a pair of plates 172
disposed on either side of the casting drum 10' and
bolted to the cross members 164. The plates 172 termin-
ate, at their tops in respective mounting pads 174 towhich pillow blocks 176 are bolted. The pillow blocks
176 rotatably support a shaft 178 to which the upper
cutters 132 are mounted.
A doctor blade supporting bracket 182 is located
on either side of the casting drum 10' and as seen in
Figure 5 is pivotally mounted on hollow shafts 214,
21~. Rotation of the doctor blade support brackets 182
is prevented by a strut which extends from the bracket
to a frame member (not shown). A shaft 188 is supported
by bearings in the doctor blade and rotatably mount the
~ 3 ~ 3 2
18
lower cutter wheels 134. Ring ~ears 190, 192 (shown
best in Figures 6 and 8) mounted to respective cheeks
220', 226' engage drive gears 194, 196 attached to and
forming part of the upper cutters 132 so that the cutter
shaft 178 driven by sprocket 1001 (on head shaft 300)
which drives sprocket 1000 through chain 1002 insures
the synchronization of the strip 40', the belt 14' and
the drum lO'.
As indicated above, the yoke assembly 148 which
rotatably supports the casting drum 10' is spring biased
by an adjustable spring assembly 150. In particular,
the yoke assembly 148 includes a pair of lateral support
members 148a, 148b interconnected at one end by a cross
piece 200. A pillow block 202 (shown best in Figure 5)
is bolted to each lateral member and pivotally supports
the yoke assembly about the head shaft 106.
The spring assembly 150 includes a threaded rod
20~ fixe~ to an extension plate 206 that is attached to
the frame member 162. A gusset plate 206a rigidizes
the mounting of the extension plate 206. The threaded
rod 204 extends through an apertured tab 208 extending
from the yoke assembly 148. A spring 210 acting between
a nut 212 and the tab 208 applies an adjustable spring
biasing force to the yoke assembly 148.
The bearing assemblies 146 which are bolted to the
iateral yoke members 148a, 148b, rotatably support
hollow shafts 214, 216 attached to opposite sides of the
casting drum 10'. The hollow shaft 214 communicates
with a water outlet 218 through which cooling water is
discharged from the inside of the casting drum 10'
whereas the hollow shaft 216 communicates with a water
inlet 219 through which cooling water is introduced into
the casting drum 10'.
The inside of the casting drum 10' is preferably
cooled by a fast moving fluid such as water. Design
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19
parameters such as quantity and velocity of water flow,
drum and belt thickness and conductivity, etc., are
varied by methods wall known to those skilled in the
art to provide adequate cooling of the casting and of
the various machine parts.
Referring to Figure 7, a cooling gap is defined on
the inside of the casting drum 10' between an outer
cylindrical shell 220 and an inner shell 222. Vanes
224 and inlet and outlet apertures (not shown) are
arranged to pump trapped air from the drum by directing
it to the outlet conduit (hollow shaft) 214. Water is
directed into the drum 10l by the inlet conduit (hollow
shaft~ 216. The side cheeks 22a', 22b are cooled by
spray nozzles or other suitable cooling arrangements
known in the art.
The belt drive roller 104, as best shown in Figure
8, comprises three equally spaced disc plates 226 fixed
to a support hub 228. The support hub in turn is keyed
to the through head shaft 3~0 which as described above
is rotatably supported by the pillow blocks 170~ With
the disclosed construction, sufficient support for the
belt 14' is provided by the roller while providing
clearance and accPss space for the cooling conduits 120b
~shown in Figure 7) through which cooling water is
1 25 sprayed onto the underside of th belt 14'.
¦ Turning now to Figures 5 and 9, a belt
1 position/tension adjustment indicated generally by the
¦ reference character 112 is illustrated. The apparatus
1 112 is used to make belt tracking adjustments to the
¦ 30 belt 14'. In the illustrated embodiment, a pair of
self aligning pillow blocks 230 support an idler shaft
232 to which the idler drum 110 is attached. The pillow
blocks 230 are adjustably supported be}ow the frame
cross pieces 164 by two parallel, downwardly ~xtending
~- 35 rods 236, 238, each of which is swivelably supported on
!
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its upper end by clevises 1003, 1004. These clevises
are pivoted on pins which also go through blocks 1005
which are affixed to Prame 164. 'rhreaded adjustment
members 240, 242 adjust the vertical position (with
respect to the cros~ piece 164~ o~ thle pillow block
230. A horizontal adjustment plate 244 bearing a pair
of horizontally positi~ned adiustment screws 246 are
used to adjust the horizontal position of the pillow
block on the vertical threaded shafts. Apertures (not
shown) in the pillow block 230 through which the
vertical shafts 236, 23B extend are enlarged in order to
allow relative, horizontal movement between the pillow
block 230 and the shafts 236, 238.
Bearings 230 are self-aligning via spherical seats
- 15 and the threaded rods 236, 238 (which appear on both
sides of the machine~ with their pivoting action working
I in conjunction with the swiveling action of the
i spherical bearing seats allow the shaft 232 to move in
the direction of its length (i.e., in and oui of the
paper in Figure 5).
A rigid tongue 1006 extending downward ~rom either
side of the machine frame 164 is fitted with an
adjusting screw 1007 so that the roll 110 can be
positioned sidewardly thus allowing pressure from
flanges 1008 to be exerted on one ~dge or the other of
belt 14' so that the belt is kept on track. The
distance between the inside of the flanges on roll 110
is equal or just somewhat greater than the belt width.
Turning now to Figure 6, details of the casting
drum 10' and cheek mounting are illustrated. Each of
the cheeks 22a', 22b' de~ines an annular recess 250 to
accommodate water cooling jets or sprays for cooling
the cheeks 22a', 22b'. The ring gears 190, 192 which
run with the upper cutters 132 are bolted to the side
of respective cheeks by a plurality of threaded
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fasteners 256~ As described above, surfaces 46'
confronting and sealingly engage sides 48l of the
casting drum lO'. The tapered surfacP 44' defines the
ear receiving recess 50~ on each side of the casting
drum lO' which increases in the radial and transverse
dimensions as the end o the casting arc is approached.
The cheeXs 22a', 22b' are suppo~:ed by ball
bearings 262. Each chPek member defines a curved
surface 266 defining an outer race for the bearings
262. A spring loaded annular member 264 defines an
inner race engaged by the bearings. Threaded pins 268
acting against springs 270 are used to place an
adjustable biasing force on the outer race member 264.
The pins 268 are threadedly mounted in the support plate
172 which is bolted to support base lO09 (which is
bolted to the cross piece 164).
Turning now to Figure 8, the drive system for the
machine is illustrated. As indicated above, a drive
I motor is used as a motor force for imparting rotation
1 20 to the casting drum 10' and the belt 14' by means of a
chain drive. In order to provide a means for driving
the belt 14' and casting drum 10' in opposite directions
and at slightly different speeds, the differential
mechanism indicated generally by the ~eference character
109 is utilized. The differential mechanism comprises
, input and output side gears 288, 286 respectively
positioned on each side of a pinion carrier 290 which
rotatably carries at least two pinion gears 292 that are
coengaged by the side gears 286, 288. An input shaft
300 is driven by the drive motor (not shown) through a
j chain drive or other suitable arrangement. A sprocket
~ 1010 freely turning on the input shaft 300 is operative-
¦ ly connected via sprocket chain 1011 to a drive sprocket
l 302 fixed to the drive shaft 214 for the casting drum
~, 35 10' so that rotation of sprocket 1010 rotates the
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22
casting drum 10'. The speed of rotation of the castiny
drum is directly adjustable by adjusting the ~peed o~
the drive motor 108. SprocXet 1010 iS turned in the
opposite direction ~rom shaft 300 (and rolls 100 and
104) by means which will now be described.
The input side gear 288 is rigidly affixed to the
head shaft 300 throuqh a conventional keyed hub arrange-
ment 289. The differential carrier 2'30 includes a
sprocket 312 which is connected to an auxiliary drive
314 by a chain or other suitable arrangement. When the
differential carrier 290 is prevented from rotating, the
rotation in the input shaft 300 will be transferred to
the side gear 286 in a one-to-minus one relationship,
i.e. one revolution of the input shaft 300 will produce
one revolution in side gear 286 in the opposite
rotational direction and hence the sprocket 1010 will
drive sprocket 302 via chain 1011 which thus drives drum
10' through shaft 216 in the opposite direction to
- roller 104. The ratio of diameters of sprocket 1010 to
sprocket 302 is nearly the same as the ratio of
diameters of roller 104 to drum 10' so that the drum and
belt surface speeds are nearly the same. If the
auxiliary drive 314 i~ energized to cause the carrier
290 to slowly rotate, the speed of the output side gear
286 relative to the input side gPar 288 will be reduced
-i- or increased depending on the direction and rate of
-~ rotation. By varying the speed of the auxiliary drive
314, precise differential speeds can be imparted to tne
drive sprocket 1010 to adjust for differences in surface
speed between the casting drum 10' and the belt 14'.
The auxiliary drive 314 may be powered by an adjustable
electric motor, hydraulic drive motor and other drive
mechanism known in the art.
In operation, the drive motor is adjusted to
produce a desired surface speed of the belt in order to
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23
provide sufficient contact time for the molten metal in
the casting arc 20'. The auxiliary motor driving the
differential mechanism ~when used) is then adjusted to
produce the requisite surface speed of the drum 10'.
¦ 5 Once the pxoper speeds have been reached, drum, belt and
' cheek cooling water is turned on and molten metal is
intrsduced into the casting arc 20' by way of a conduit
316 which feeds molten metal to a downwardly direct
nozzle 318. It should bP noted that other arrangements
1 10 for introducing molten metal are also contemplated by
'7 the present invention and this invention should not be
`1 limited to the disclosed conduit and nozzle. Additional
3 post nip strip cooling sprays ~not shown) are also of
value to further reduce the temperature of the offcoming
strip.
Turning now to Figures 10-12, another embodiment of
the invention is illustrated. In this embodiment, the
~ principles of the invention are applied t9 a Bessemer
'~ type machin~. As is known, in a Bessemer machine, two
1 20 parallel rolls 400, 402 rotate about horizontal axes
404, 406. The rolls 400, 402 define converging casting
surfaces 400a, 402a, respectively. A nip indicated
1 generally by the arrow 406 is defined between the rolls
! and determin~s the casting thickness of the strip.
A molten pool 410 is confined between the rolls
400, 402 above the nip 406 by edge constraints formed by
pairs of belts indicated generally by the reference
~ character 412, 414. The edge constraint 412 is defined
:~ by a pair of belts 412a, 412b reeved around pulleys 416,
418. The belts 412a, 412b are positioned in a jux-
~l taposed, but angled position. Outer edges of the belts
.l ride against respective sides 400b, 402b of the casting
! rolls 400/ 402. As in the first embodiment, the belts
,~ in effect define expanding/ ear-receiving recesses 419
j 35 associated with the sides of the rolls. These recesses
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24
accommodate the growth of the ears e' as the cast strip
s' is formed on the casting surfaces 400a, 402a. The
ears e' are Eormed on the surfaces of the belts 412a,
412b and the sides of the rolls 400b, 40Zb that are in
confronting relation with each other.
Unlike the first embodiment, the strip formed by
this embodiment is substantially an "I-beam" in cross
section as seen in Figure 12. In the preferred
arrangement, the belts forming a give~ pair abut each
10 other near the center line of the strip. Preferably
guides or belt restraints 420, 422 and 424 are used to
inhibit leakage of molten material at the belt junctures
and the belt/drum junctures. With the disclosed
arrangement, the recesses defined by the belts on either
15 side of the roll 400, 402 accommodate the ears as they
are formed during the casting process so that ear
crushing or interference does not occur at the nip.
Turning now to Figures 13-16, the invention is il-
lustrated as it would be embodied in a converging
20 belt-type machine. In this embodiment, casting surfaces
are defined by a pair of continuous belts 450, 452 which
are reeved about rollers 454, 455, respectively. In the
preferred construction, the belt 450 is substantially
vertically oriented and defines a vertical casting
25 surface 456. The belt 452 defines an arcuate casting
surface 458 that converges towards the belt 450. The
curved path for the belt 452 is provided by a guide 460
which includes, as best seen in Figure 15 side members
460a, 460b. The belt 452 rides along the edge of side
30 members 460a, 460b. Seal members 466 may be provided to
prevent leakage of molten material and coolant betwaen
the side members 460a, 460b and the underside of the
belt 452.
The side members 460a, 460b are so shaped that in
35 the illustrated embodiment, an arcuate-shaped upper
~ 3 ,~ ~ 5~ 3 r3
portion is defined having a radius R. The arcuate upper
portion may merge into a straight portion having a
length A, as shown in Flgure 14. The straight portion
would provide support for the strip s " during an
additional cooling time for the ~trip.
As seen in Figure 15, the belt 452 is preferably
narrower than the confronting belt 450. The molten pool
is contained by edge constraints which are each de~ined
by a belt of cheek blocks 470. The cheek blocks 470a
~ 10 are hingedly interconnected by hinge connections 471.
t As seen in Figure 15, each individual cheek block 470a
is tapered in cross section and includes an inner
recess-like surface 472 which curves inwardly and merges
with a substantially flat side surface 474. The side
surface 474 abuttably engages a side surface 462, 464 of
the associated guide member 460a, 460b.
, In the preferred arrangement, the belts of blocks
470 move in synchronism with the belts 450, 452.
' Because of the curvature of the guide 460 (provided by
¦- 20 the side members 460a, 460b), an expanding recess 475 is
defined between each belt of blocks 470 and the
~ associated side surface of the side members 460a, 460b,
'! as the end of the casting arc is approached. With this
i arrange~ent, the growth of the ears is accommodated as
j 25 the strip being cast proceeds from the top of a molten
., pool to the end of the casting arc. As seen in Figure
16, the resulting strip s " is substantially U-shaped in
crvss section with tapered ears e " defining the legs of
the U.
In the illustrated embodiment a clearance c (see
~ Figure 15a) is provided between the cheek brocks 470a so
il they will not "clap" when running at high speeds. It is
believed that a clearance c of .010 inches will provide
satisfactory resu-ts. With this relatively small
clearance space, fins will not form because of flashing
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~3
26
between the blocks. Any such flash will be trimmed away
when the ears e " are removed ~rom the strip ".
It should also be apparent that hoth sides of the
machine could be built with a curved be}t 452 ~instead
of one straight belt 450 and one curv~sd belt 452). In
this alternate embodiment, the recess defined by the
cheek blocks would be similar to the recess defined by
the belts in Figures 10 and 11. In otherwards, the
resulting strip would be I-beam-shaped in cross section.
In this alternate arrangement, both casting belts would
be the same width.
Figures 17-19 illustrate another embodiment of the
invention. In this embodiment, the principles of the
~ invention are adapted to an "in-the-ring" (ITR) type
j 15 machine. The machine is defined by a drum 500 rotating
¦ within or inside a ring 502. Casting surfaces are
defined by a cylindrical surface 500a defined by the
exterior of the drum 500 and an inner cylindrical
, surface 502a defined by the inside of the ring 502. A
converging casting arc 504 is defined between the drum
and the ring. The molten pool is contained by edge
constraints (only one is shown) which are defined by
arcuately oscillating cheeks 506. ~ethods and apparatus
for oscillating the cheeks are known and are considered
conventional and therefore the mechanism for producing
oscillations in the cheek 506 will not be discussed
' further.
~' As seen Figure 18, the cheek 506 is an arcuate
segment in configuration and has radius of curvature
that preferably conforms to the radius of the ring 502.
The cheek 506 defines a tapered surface 510 which merges
with a side surface 512. The side surface 512 abuttably
engages a side 514 of the drum 500. The cheek 506 also ,
includes a ring engaging portion 506b which includes a
side surface 516 that rides against a side 502b of the
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3~J.
` 27
ring 502. As is the case with the other embodiments,
each cheek 506 defines an ear accommodating recess 519
that expands in the radial direction as the end of the
casting arc is approached. In this way, the growth of
ears e " ' as the ~tr~p Bl I I iS formed between the
casting surfaces, is accommodated.
In this embodiment, the cast strip s " ' is
~ substanti~lly U-shaped in cross section with the ears
j e " ' defining the legs of the "U". As seen in Figures
I 10 17 and 19, a mechanism for trimming the ears from the
I cast strip is illustrated. The trimmer includes a
cutter wheel 520 rotatable about a substantially
vertical axis 522 which also rides against the side 502b
of the ring S02. A second cutter 524 rotatable about a
: 15 slightly skewed axis 526 overlaps the edge of the cutter
520 and thus cuts the ear from the strip as the ear
passes between the cutters. As seen in Figure 17, the
trimmed ears spiral from the ring 502. The strip itself
preferably spirals from the inside of the ring in the
manner disclosed in U.S. Patent No. 3,756,304.
Although the invention has been described with a
certain degree of particularity, it should be understood
that those skilled in the art can make various changes
to it without departing from the spirit or scope as
hereinafter claimed.
