Note: Descriptions are shown in the official language in which they were submitted.
~9237~
BACKGROUND OF THE INVENTION
This invention relates to continuous casting machines
for continuously casting metal ingot, strip, slab or bars
directly from molken metal in a casting region defined between
spaced portions of a pair of revolving, flexible, endless
casting belts which are moved along with the metal being cast,
often called twin-belt casting machines or twin-belt casters.
The invention is described as embodied in the structure
and operation of twin-belt casting machines in which the molten
metal is fed into a casting region between opposed, portions
of a pair of moving, :Elexible belts. The moving belts confine
the molten metal between them and carry the metal along as it
soli.difies into a bar, strip, slab, or ingot, hereinafter
called the "cast product" or "product being cast" or similar
words. Back~up means, usually rollers having narrow circum-
ferential ridges or fins support and guide the belts while
holding them accurately positioned and aligne~ as they move
along so as to produce the cast metal product.
These back-up rollers are positioned across the
machine carr;.ages so as to roll passively when the casting
belt grazes each of them under pressure of the head of molten
metal and/or the weight of the metal Their circumferential
fins permit the passage of cooling llquid along the respective
casting belt without notably impeding heat transfer themselves.
The fins have often been made separately from the roller shafts,
but in current machines the ~ins and shafts are now oEten
made integrally as one piece of metal. Vast quantities of
heat liberated by the molten metal as it solidifies are
~1~237~
withdrawn through the portions of the two belts which are
adjacent to -the metal being cast. This large amount of heat
is withdrawn by cooling the reverse surfaces of the belts by
means of the rapidly moving liquid coolant traveling along
these surfaces. The edges of the molten product are contained
between a spaced pair of side dams in the form of a plurality
of hlocks strung together on flexible metal straps to form a
pair of endless flexible assemblies suitable for containing
the molten metal as it solidifies.
Background information on twin-belt casting machines
will be found in U. S. Patents:
Patent Mo. Inventor(s~
2,640,235 Hazelett
2,904,860 Hazelett
3,036,348 Hazelett et al
*3,123,874 *Division of No. 3,036,348
*3,142 r 873
*3,228,072 " " " "
3,041,686Hazelett et al
3,167,830 " " "
3,310,849 " " "
3,828,841 " " "
3,848,658
3,864,973 Petry
*3,921,697 *Division of No. 3,864,973
3,865,176 Dompas et al
*3,955,615 *Division of No. 3,865,176
*4,155,396 " " "
3,878,883 Hazelett et al
- *3,949,805 *Division of No. 3,878,883
*3,963,068 " " "
3,937,270 Hazelett et al
*4,002,197 *Division of No. 3,937~270
*4,062,235 ,- Il 11
*~,082,101 " 17 11
3,937,274 Dompas
4,092,155 Dompas et al
4,150,711 Hazelett et al
--4--
~ 7 ~
In machines of this type, the moving belts are thin
and are cooled by substantial quantities of liquid coolant,
usually water containing corrosion inhibitors. This coolant
withdraws heat through the casting ~elts and serves to cool
the metal from its molten state as it enters at one end of the
machine causing it to solidify as it passes through the machine.
The molten metal pushes outwardly on the belts due to
metalostatic pxessure or "head". Solidification of the metal
product takes place from outside to inside so that, through
some of its passage through the machine, it is in the form of
a solidified shell having a molten, constantly decreasing,
interior volume. It will also be understood that, as the
metal cools and solidifies, it shrinks. The shrinkage is
very slight but, nevertheless, is sufficient to cause surface
regions of the metal sometimes to pull away from the moving
belts or from the side dams. When this separation between
areas of the metal surface and the cooling surface occurs,
non-uniform cooling is caused, which results in non-uniformities
in the parameters of the casting region and in non-unifor~ities
in the cast product.
~ his invention in certain aspects is especially
applicable to casting machines which produce ingot or slab
of a width in excess of 25 inches (635mm). Such twin-belt
casting machines are genera:Lly inclined downward in use, so
as to result in a head - tha~ ist a static pressure -- of
liquid metal in order to ~ill out the casting region, i.e.
the mold cavity, and to thereby press the casting belts
decisively against their back-up supports. Further, by use
of open-or closed-pool pouring technique, the entry o~ molten
metal into the machine is facilitated by operating the machine
--5--
at some downward incline. The aforesaid head of molten metal
depends on the angle of incline, the density of the molten
metal being cast, and the distance to the point of final
solidification in the machine~
The force of such liquid metal head is exerted upon
the casting belts and thence upon the guides or back-up supports
for the belts, which we commonly call the mold back-up. Most
immediate]y, this back-up consists of transversely disposed
finned back-up rollers. These rollers and their supports
have previously been made rigid in order that the ingot or
slab of accurately defined and controlled gauge may be cast.
The headers bearing liquid coolant can be made to serve the
additional duty of providing rigid supports for the back-up
rollers. Some wide machines have in their carriages central
longitudinal beams or sills -~o lend their additional rigidity
to the back-up system, for resisting the force of the molten
metal to be counteracted as it presses outwardly on the
wide casting belts.
The very rigidity of the above described prior art
back-up means can combine with the shrinkage inherent in the
freezing and cooling of the product being cast to allow air
spaces to intervene between the freshly cast surface and the
casting belts. These intruding spaces substantially reduce
the rate of heat transfer and may render it non~uniform, with
a corresponding effect on the rate and uniformity of product
cooling and solidlfication. The reduced rate and uniformity
of ooling limits the production rate, or else it requires
the use of longer casting machines than would otherwise be
needed.
--6--
~23'73
An associated problem w.ith the aforesaid air spaces
or gaps occurring between the cast metal surface and the mold
surEaces defining the casting region is the consequent degrada-
tion of the desired fine, quick-chilled crystalline structure
in the cast product into coarser crystalsO Such air spaces
or gaps can perm.it the localized remelting of the cast product
with consequent bleeding, or sweating of molten materiaL from
the previously cast shell itself and/or from the molten metal
inside of the shell causing segregation and/or porosity in
the cast product. This reheating or remelting will not occur
if good mold contact is maintained.
Problems o local excess pressure can occur with a
rigid mold when excess thickness is somehow frozen locally.
Thus, the relatively thin casting belts will become locally
overheated with a corresponding localized area of increased
heat transfer due to the high localized belt pressure against
the partially solidified product. Also, if a frozen piece
of metal of e~cess thickness is inadvertently drawn into the
caster, a slitting of the belt by the narrow fins of the
back-up rollers or considerable damage to the precise, rigid
mold back-up mechanisms can result.
_UMMARY OF THE INVE~rrION
It is an object of the present invention to provide
methods and systems for continuously casting metal products
of high quali.ty directly from molten metal wherein flexibi]ity
and con-trol of -~he transverse shape of the casting region
are provided.
Continuous casting methods and systems are advanta-
geously provided wherein the con-tact pressures between the
casting belts and the metal product are controlled and are
maintained along the length of the metal to insure uniform
heat extraction from the solidifying metal product.
One preferred method of shaping the casting region
by action of the back-up system is to arrange for constant
parallel thickness in the upstream casting region, before the
product being cast is solidified enough to retain its shape,
and to allow springy bowable rollers and back-up supports
to converge in the downstream portion of the casting region
as the largely solid product contracts due to loss of heat
It is convenient in twin-belt casting machines to
make structural use of the transverse headers carrying the
cooling liquid to the nozzles which apply the coalant over
the casting belts. This convenien~e is important in view of
the lack of space for transverse beams in the belt carriages.
In downstream areas of the carriages where less coolant is
needed because the product has already formed its solidified
shell, there is room for such special transverse ~eams. The
relative bowability of such transverse support beams and
coolant headers enters into the total effective bowability
of the array of back-up rollers.
There are various aspec-ts of the methods and systems
of the present invention for shaping the casting region. ~n
certain aspects, the "head" of the molten metal is predetermined
and is used as the driving force for bowing or deflecting
the back-up rollers and their support systems in one carriage
only, preferably those in the upper carriage while the back-up
rollers and support systems in the other carriage are rigid;
_~ ~
~12373
and predetermined bowability is intentionally provided in the
back-up rollers and in their support systems in said one
carriage for responding to this force of the head of rnolten
metal, while the back-up rollers in the other carriage are
rigidly constrained. In certain other aspects mechanical
adjustment means are used for applying bending forces to the
back-up rollers and/or to their support systems for producing
bowing of the back up rollers in one or both carriages for
shaping the casting region. In certain additional aspects,
remotely controllable bowing means are used for controllably
applying bending forces to the bowable back-up rollers in
one or both carriages for shaping the casting region.
In accordance with certain aspects of the present
invention a first one of the casting belts is flexibly constrained
in a predetermined relationship versus the molten metal head
values occurring at different locations in the downwardly inclined
casting region for enabling this first belt to bow transversely
away from the casting centerline due to the predetermined molten
metal head values occurring at the various locations, with the
second casting belt being rigidly constrained and being trans-
versely bowed toward the casting centerline in a predetermined
inward convex configuration that compensates for the various
displacements of the flexibly constrained belt, resulting in
a uni~orm transverse cross section for the cast product, while
providing improved casting parameters.
Among the advantages of this invention are those
resulting from continuously casting metal product directly
from molten metal wherein the shape and con-tact pressure and
parameters of the belt supports may be controlled by manual
adjustment or by remote control.
_g_
3~
In carrying out this invention in certain illustrative
embodiments thereof, methods and systems are provided for
casting metal product directly from molten metal in order -to
promote uni~orm heat transfer ~rom the cast metal to the belts
which are continuously liquid cooled. The upper back-up rollers
are selec~ively bowed down either by manual adjustment or by
remote control, and the lower back-up rollers are allowed to
~ield or "float", or vice versa. The methods and systems as
disclosed include intentionally rigidizing the upper or lower
back-up rollers or sections thereof while the back-up rollers
on the other side are allowed to flex in predetermined amounts
with the surface of the casting. These methods and systems
include bowing both sets of the back-up rollers either inwardly
or outwar~ly; bending structural frame members which are in
support relationship with the rollers for flexing the rollers
to contrvl belt contour and belt contact with the cast product,
etc.
The maintenance of contact between the casting belts
and the cast product is controlled by either manual adjustment
or remote actuation. In any of the methods and systems the
mold con~iguration may be tapered from the upstream to the
downstream end of the continuous casting machines for co~pensat-
ing for shrinkage in the solidi~ying metal and for providing
predetermined mold contact pressures and heat transfer
characteristics.
BRIEF DESCRIPTION O~ T~E DRAWINGS_ __
The invention, toge-ther with further objects, aspects,
advantages and features thereof will be more clearly understood
from a consideration of the following description taken in
conjunction with the accompanying drawings in which like
elements will bear the same reference designations throughout
the various E[GURES:
~10-
~2~7~
FIGURE 1 is a perspective view of the inpu-t or
upstream end of a continuous casting machine embodying the
present invention, as seen looking toward the machine from a
position in front of and outboard beyond the outboard side of
the two belt carriages.
FIGURE 2 is an elevational view, partly broken
away and in section, of a prior art machine as seen looking
toward the outboard side of the two belt carriages, showing
the casting region downwardly inclined at a predetermined
angle of inclination.
FIGURE 3 is a cross~sectional view of portions of the
two belt carriages of the prior art machine including the liquid
coolant headersr back-up rollers, casting belts and side dams
showing such back-up means and the associated belts and side
dams rigidly defining the casting region.
FIGURE 4 is a top or plan view of the lower carriage
of this prior art machine with the belt and parts of other
elements cut away for revealing the structure.
FIGUR~ 5 is a partial side view of this machine
enlarged as compared with FIG. 2; for convenience of illustration
the casting region is shown horizontal, but it is to be under-
stood -that the casting region is inclined downwardly as shown
in FIG. ~.
FIGURE 6 is a transverse sectional view o~ the casting
region, showing a segmented back-up roller below the lower
casting belt, with the segments disposed along a shallow,
convex upward arc, in opposi-tion with a f:Lexible back-up
roller above t~e upper belt as it would appear under the
pressure o~ a head of molten metal exerting force from within
the casting region between the belts.
~9~373
FIGURES 7A, 7B and 7C show an enlaryed elevational
view of a three-segment back-up roller with integral circumferentic
fins.
FIGURE 8 is a further enlarged partial sectional view
of a portion of FIG. 6 showing the means for interconnecting
the adjoining ends of two segments of a se~mented back-up roller.
FIGURE g is a view similar to FIG. 6 showing intermed-
iate, flexible snubbing bearing back-up means for the flexible
back-up roller for providing predetermined control of its
degree of flexibility.
FIGURE 10 is a transverse section of a twin-belt
caster in which the belt shape and contact control is provided
by transversely do~nwardly bowing the upper back-up rollers and
by mechanical adjustment and allowing the lower back-up rollers
to yield.
FIGURE 11 is a transverse section of a twin-belt
caster as illustrated in FIGURE lO showing another mechanical
adjustment means.
FIGURE 12 is a transverse section similar to FIGURE
11 in which the mechanical adjustment for the back-up rollers
includes a compliance member. FIG. 12A is an enlargemen-t.
FIGURE 13 is a transverse section of a twin-belt
caster similar to FIGURES 10, ll & 12 illustrating remote
control bowing of the back-up rollers using fluid cylinder
actuation.
FIGURE 14 is a transverse section of a twin-belt
caster illllstrating the use of rigidly supported lcwer back-u~ rollers
with a stiffened center section in the bowed upper back-up
rollers for control of belt contact with the product being
cast.
~12-
~v~v ~ ~
FIGURE 15 is a transverse section of the caster of
FIGURE 14 lllustrating the use of remote control for belt
contact control.
E'IGURE 16 is a lonyitudinal, elevational section of
the casting region illustrating the use of a selectively tapered
mold configuration along -the casting region.
FIGURE 17 is a transverse section of a twin-belt
caster employing symmetrical inward bowing on both the upper
and lower back-up rollers by remote control through fluid
cylinder actuation.
FIGURE 17~ is a modification of the method and
system of FIG. 17.
FIGURE 18 is a transverse section of a bar-type
twin-belt caster illustrating the casting zone before shrinkage
of the product being cast.
FIGURE 19 is a transverse section of the bar caster
shown in FIGURE 18 after shrinkage has occurred, illustrating
piston rod actuation for bending the back-up rollers to
maintain belt contact in the downstream portion of the casting
region.
FIGURE 20 is a transverse section of a wide caster
illustrating the bending of a structural frame member in order
to bow the back~up roller supported by such frame memberO
FIGURE 21 is a transverse section of a wide caster
similar to FIG. 20 utilizing a more bendable (compliant)
member in order to bow a stiffer frame member in order to
provide a finer (more precise) bowing adjustment of such
frame member.
FIGURE 22 is a transverse section of a wide caster
illustrating the bending of a lower frame member by a remotely
actuable fluid cylinder connected to the center of the frame
member.
FIGURE 23 is a transverse section of a wide caster
illus-trating the bowing of a structural frame member in the lower
carriage using a more compliant member and a remotely actuatable-
fluid cylinder connected to the center oE the compliant member.
FIGUR~ 24 shows the use of a more compliant member
for bending a stiffer member, with two ac~uatable fluid cylinders
located at the respective ends of this compliant member.
FIGURE 25 shows the progressive tapering of the down-
stream portion of casting region by means of a fulcxumed lever
driven by a fluid-actuated cylinder for simultaneously bowing a
plurality o~ transverse frame members, each one slightly more
~han the preceding one.
FIGURES 26 and 27 show two different embodiments of
resilient gauge spacers mounted between the side frames of the
upper and lower carriages.
DESCRIPTION OF THE PREFERRED EMBO~IMENTS
Re~erring now to FIGURE 1, a continuous casting
machine, referred to generally with the reference character
10, has molten metal fed into the upstream end or entry 11
of the machine 10 between upper and lower endless flexible
casting belts 12 and 14u The molten metal is solidi~ied in
a casting region ~ (FIGURE 3) defined by the spaced parallel
surfaces of the upper and lower casting belts 12 and 14.
It is noted that FIGURE~ 1, 2, 3, 4 and 5 show
prior art structures, and it is helpful to the reader to
understand these prior structures as background for the
present invention.
The cas~ing belts 12 and 14 are supported and
driven by means of upper and lower carriage assemblies ~Jhich
-14-
3 ~2~3
are indicated in FIGURES l, 2 and 3 at U and L, respectively.
The carriage assemblies are supported in cantilever relationship
from a main frame 23, as seen in FIGURE l. Hence the side of
each carriage assembly near this main frame 23 is referred to
as being "inboard" while the other side is referred to as
"ou-tboard".
The upper carriage U includes two main roll-shaped
pulleys 16 and 18 (FIGU~ES 2 and 5) around which the casting
belt 12 is reYolved as indicated by the arrows. The pulley
16 near the input end of the machine lO is referred to as the
upstream pulley or nip pulley and the other pulley 18 is
called the downstream or tension pulley. Similarly, the
lower carriage L includes main upstream (or nip~ and downstream
roll-llke pulleys 20 and 22, respectively, around which ~he
lower casting belt 14 is revolved. In order to drive the
casting belts 12 and 14 in unison, the upstream or nip pulleys
16 and 20 of both the upper and lower carriages are jointly
dri~en through universal-coupling-connected drive shafts 24
and 25 by a mechanically synchronized drive 26 driven by an
electric motor (not shown).
During the casting operations, the frame l9 (FIG. l~
of the upper carriage assembly U is supported on the frame 21
of the lower carriage assembly L through gauge spacers 17
positioned along the length of the casting region on either
side, and the precise thickness of these gauge spacers
establishes the mold thickness dimension between the opposed
casting faces oE the casting belts 1~ and 14 and correspondingly
the resulting thickness of the cast metal product. Two edge
dams 28~only one of which is seen in FIGIJR~ 2) are interposed
between the opposed casting faces of the casting belts and
~15-
3~3
are guided. Each edge dam is laterally constrained to estab]ish
the cast metal width at the nip or upstream end of the casting
machine by an edge dam guide assembly 30~
These -two edge dams are driven through frictional
contact with the casting belt 12 and 14. The two opposed
inner casting faces of these edge dams, together with the
two opposed casting faces of the upper and lower casting
bel-ts 12 and 14 form four moving casting faces of a moving
mold in the casting region C having a generally rectangular
cross sectional configuration as seen in FIG. 3. As will
be observed in FIG. 2 from the angle "A", the upper and lower
carriages U and L are slightly inclined with respect to hori-
zontal so that the casting region C slopes slightly downwardly
~rom the upstream end 11 of the machine 10 to the downstream
or exit end 31. Usually the downward inclination "A" is less
than 20 from horizontal, and it can be adjusted by means of
the jack mechanism 29.
Casting belts 12 and 14 are relatively thin metal
belts, for example, of steel which require back-up support
and an enormous amount of cooling in order to be able to hardle
the heat liberated by the solidifying metal in the casting
region C. It is desirable to maintain the casting belts 12
and 14 in intimate contact with the cast metal as it solidifies
in the casting region, for avoiding air spaces or gaps between
the surfaces of the solidifying metal and the casting belts
12 and 14, for reasons as discussed ahove in the background
section. Among the problems is that the metal shrinks as
it solidifies. Furtherrnore, such shxinkage varies somewhat
in different areas of the casting region C. The molten
metal is initially fed in between the casting belts 12 and
14 from a tundish 32 (FIG. 2) at -the upstream end 11 of
-16
~ 3~3
the casting region C. The molten metal in the downwardly
inclined casting region pushes outwardly,i.e.,upwardly and
downwardly, against the belts due to metalostatic "head"
pressure. As it continues downstream in the casting region
this "head" pressure increases. Even after a thin shell of
cast metal forms around the molten core the head continues
to increase, pressing this shell forcefully outward. Then,
as the shell thickens and the molten core begins to solidify,
the head ceases its outward pressure and thereafter shrinkage
of the solidifying product becomes progressively greater in
the downstream portions of the casting region.
Generally speaking the shrinkage tends to take place
away from the upper belt 12, because the weight of the cast
product rests upon the lower belt 14. Thus, the conductive
transfer of heat from the solidifying metal into the lower
belt tends to be more uniform than the transfer of heat into
the upper belt in the downstream portions of the casting
region. Wherever the upper belt is locally separated from
the upper surface of the solidifying product there is no
heat transferred by conduction and a radiant or convective
heat transfer occurs. ~ny separation gaps or spaces between
areas of the solidifying metal surface being cast and the
belts to which coolant is applied creates hot spots and non-
uniform heat transfer which result in crystallographic
degradations, segregations, porosity, and imperfections
in the cast product as discussed in the background section
above.
As will be seen in FIGURES 2, 4 and 5 the upper
and lower belts 12 and 14, respectively, are backed up
by a plurality of upper back-up rollers 33 and lower back-up
17-
~9t2
373
rollers 34, respectively, e~tending transversely above and
below the casting region C. The lower frame 21 in the lower
carriage L incl~ldes a core section 36 therein, which may be
built to be removable as a whole unit. This core section 36
includes a plurality of ri~id coolant headers 38 and a frame
member 40 by which the lower back-up rollers 34 are supported.
As will best be seen in FIGURE 3, the upper carriage
U has an upper frame 19 including a similar core section 37
therein which includes a frame member 44 and a plurality of
rigid coolant headers 46 which support the upper back-up
rollers 33. This core section 37 may be built to be removable
as a whole unit.
It is to be understood that these prior art coolant
headers 38 and 46 together with their respective frame members
40 and 44 were made as rigid as possible. The coolant headers
38 were each formed with a large rectangular cross sectional
shape in the nature of a box beam for resisting significant
deflection. The liquid coolant is fed into the rigid headers
38 and 46 through the li~uid supply connections 48 and 49.
In order to rigidly mount the lower and upper back-up rollers
34 and 33 onto the rigid headers 38 and 46, there are a
plurality of laterally spaced longitudinally extending
stringers in each carriage in the form of lower L-shaped
members 50 and upper L-shaped members ~2 secured to the
respective headers by brackets 53 (FIG. 4). For Eur-ther
in~orma-tion concerning the structures shown in FIGS. 2, 3, 4
and 5, the reader's attention is invited to Patent ~o.
3,828,841 mentioned in the background section.
-18~
The back-up rollers 33 and 34 had solid shafts 43
and S~, respectively, which were either seymented or continuous.
When these shafts were segmented, their ends were mounted in
bearings rigidly supported on the stringer members 50 and 54
for being as rigid as possible. The inboard and outward ends
of the shafts 43 and 54 were mounted in bearing 56 and 58,
respectively, so as to be freely rotatable by the moving belts
12 and 14 as they revolved in the carriages. Back-up rollers
33 and 34 have narrow circum~erential ridges or fins 55 which
are contacted by the upper and lower belts 12 and 14~ The
cooLing fins 55 provide access around the back-up rollers 32
and 34 so that coolant from the headers 38 and 46 may be
app:Lied to and maintained travelling rapidly along the reverse
sur~aces of the casting belts 12 and 14. The headers 38 and
4~ have a series of nozzle openings 60 (FIG. 5) along the
length thereof and applicator scoops 61 so that li~uicl
coolant is continuously applied to the belts and maintained
traveling rapidly along the~. By cooling the belts heat is
extracted by conduction through the belts from the casting
region C which liberates enormous amounts of heat as the molten
metal therein cools and solidifies.
In FIG. 5 the casting machine is shown in horizontal
position for convenience of illustration, but it is to be
understood that the machine ac-tually is inclined downwardly
in operation as shown in FIG. 2.
To this point the description of FIGS~ 1 through 5
is of conventional structures which have proven to be advanta-
geolls over other types of continuou,s casting methods and
Machines. In accordance with the present invention a variety
of methods and systems are provided for shaping ~he casting
region in a ~win-belt casting machine for improving heat
--19--
transfer and product uniformity and for enhancing machine
performance. Among the advantages oi such shaping are that
the be]ts will maintain contact with the surfaces of the metal
being cast in the casting region in order to provide uninter-
rupted contact between the belts and the product being cast
for providing a predictable heat extraction from the solidifying
metal into th~ belts which is comparable for both the upper
and lower belts.
In order to assure maintaining contact of both belts
with the solidifying metal as shown in FIGS. 6, 7 and 8, the
upper back-up rollers 133 are constructed to be flexible for
bowing transversely to the casting region C, while the lower
back-up rollers 34 are held rigidly in position. The respective
roller shafts 63 and 64 both are hollow. Each upper roller
shaft 63 is continuous across the full width of the casting
region C and is hollow and is construc-ted with a predetermined
bowability.` The lower roll shafts 64 are segmented and have
internal segmented shafts 66 FIGS. 7 and 8 which are supported
at the ends of each of their seyments by -the support members
50.
In typical installations of such casting machines
10 the density of the metal or alloy intended to be cast and
the intended angle of downstream inclination A are specified.
Hence, the "head" or pressure of molten metal against the
belts at any given back-up roll location along the length
of the casting reyion C is predictable. Also, the flexibility
of a beam of uniform cross section under uniform loading per
~0--
3'73
unit of length (namely, each hollow roller shaft 63) is a
function of the fourth power of its free length. Since such
uniform loading per unit length against each back-up roller
is charactexistic of the pressure ("head") in -the casting
region C, the continuous, hollow upper rollers 133 in a wide
caster as shown in FIG. 6 are much more flexible (bowable)
than the lower rollers 34 which have intermediate supports 50.
Therefore, the end-supported-only upper rollers 133
have predetermined bowability and the loading against themis
predetermined. Consequently, the bow which will occur in
each upper back-up roller at each position along the length of
the casting region is predetermined. In order to compensate
for (or offset) the resultant bulge in one surface of the
cast product permitted by the flexible back~up system for the
belt in one carriage, for example in the upper carriage U as
shown in FIG. 6, a convex back-up configuration of a rigidized
belt support system in the opposing carriage is provided as
shown in FIG. 6. The convex configuration of`the rigidized
belt back-up system in this opposing carriage, for example in
the lower carriage L is predetermined with a convex curvature
which will approximately match the predetermined concave
curvature of the bowable back-up system. Hence, the cast
product will generally be cast to a uniform thickness across
its width and will have a slight transverse curvature.
It is to be understood that the transverse curvature
shown in FIG. 6 is exaggerated for purposes of illustration.
The subsequent rolling operation will remove the slight transvers~
-21-
~1~23~3
curvature harmlessly, provided the thickness of the cas-t
product is substantially uniform.
In summary, the compensation for the bulge perrnitted
by the ~lexible, bowable belt back-up in one carriage is built
right into the machine. ~Ihe desired flexibility and corre-
sponding contoured rigidity may be built into either carriage,
but preferably the upper carriage belt back-up is ~lexible
as illustrated in FIG. 6. In other words,we offset and com~
pensate for the lateral bulging penmitted by the flexibly
constrained back-up support in the, say, the upper carriage
by means of rigidly convexly contoured back-up support in
the lower carriage. In this me-thod, we retain both mold
flexibility and constant product thickness. Such compensatlon
for bulge ma~ be made progressively greater along ~he direction
of casting in the machine, in response to the increasing head
of molten metal in that direction and the resulting progressively
increasing deflection of the flexible back-up system.
The flexibility of this back-up system will not only
prevent the occurrence of gaps or insulating air spaces, but
the Eorce exerted by the flexible portion of the back-up
system ~ill effectively and controllably maintain belt contact
and conductive heat transfer and, moreover~ render such heat
transfer relatively uniform, with corresponding positiv~
resu7ts for -the progress of the casting.
The underlyiny thoughts of this method as described
a~ove for FIGS. 6, 7 and 8 ~ay be broadly characterized as
"persuasion" rather than attempting coercive domination~
In order to produce the predetermined convex configura-
tion of -the lower belt, rigid spacers 62 ~FIG. 8) of pred~termirled
-22-
~L ~ ~4Y~03'
thickness are mounted between the rigid headers 38 and the
in-termediate supports 50 for -the segmented rollers 34. AS
shown in FIG. 8, the adjacent ends of the adjacent sections
of the segm~ented internal shaft 66 are held by the support
member 50. One shaft end has a socket 65 which receives the
reduced diameter end of the adjacent section o:E the internal
shaft 66. Anti-friction bearings 67 are mounted within the
ends of t'ne adjacent sections of the hollow shafts 64 of the
lower back-up rollers 34. These bearings 67 are retained
against an internal shoulder by means of a spacer sleeve 69
held in place by a retaining snap ring 71, and there is a
smaller diameter sleeve 73 providing a space 75 for holding
grease. A cut-out space 76 in the support 50 permits the
socket end of the section of the internal shaft 66 to be removed
from the suppor-t 50, and similarly in other su1?ports 50 so
that the segmented shafts 34 can be individually removed from
the carriage and replaced, if desired.
It is to be noted in FIGS. 6 and 7, that there are
fixed stuh shafts 70 mounted in sockets in the frames 19 and
21, and the bearings 59 at the ends of the back-up rollers
133 and 34 are self-aligning bearings for permitting free
rotation of each roller even though its axis is deflected
out of alignment with the axis of the stub shaft 70.
It is to be noted, that in view of the bowabili-ty
of the back-up rollers being a fourth power function of their
unsupported length, in the case of a wide casting region C
as shown in FIG. 6 the bowability of the end-supported-only,
one-piece flexible roller 133 may be greater tnan the predeter-
mined spring constan-t value deslred, particularly a~ locations
-23-
downstream in the machine wnere the metal "head" pressure is
greater. It is not feasible to attempt to decrease their
bowability (i.e. increase their spring cons-tant) by increasing
their hollow shaft 63 diameter beyond a modest amount, because
these back-up rollers are intended to be closely spaced
lonyitudinally along the casting region for appropriately
supporting the belt. Too large a shaft diameter would inter
fere with close roller spacing.
Consequently, for wide casting regions C in order
to limit the effective bowability (i.e. to increase the
effective spring constant of the rollers 133) external means
98, 100 (FIG. 9) may be employed. For the purpose of thus
modifying roller flexibility, rolling external back-up bearings
98, 10~ for eacn said flexible back-up roller 133 may be
placed close to the roller shaft 63 and external to it, said
bearings being able to roll against said shaft 63 in the
manner of a roller wheel, one per location (see FIG. 9).
~ et this external flexibility modification is not
intended for sharply limiting the elastic bending of back-up
rollers, since any absolute rigidity in the back-up system
may cause damage by the passage of stray, prematurely frozen
metal. We prefer to mount said external back-up roller wheel
bearing 98 resiliently, in order that they may themselves
flex away from t~e casting region. Thus, -the roller wheel
98 is mounted in a bracket 99 which in turn is seated upon
a resilient mounting member 100 on the rigid header 46. This
resilient mounting 100 is formed of ribbed or castellated
rubber for providing the desired amount of compliance. Such
resilient mounting 100 somewha~ reduces or snubs the flexing
-~4-
excursion of the back-up rollers 133 to a predetermined amount.
The resilience of such mountin~3 100 may be obta;ned by means
of grooves or castellated and bonded rubber sandwich pads,
or by Belleville conical spring washers mounted on the
mountin~ bolts for the bracket 9g. The external rolling
back~up wheels 98 so mounted may or may not -touch the shafts
~3 of the respective back-up rollers 133 when the machine is
empty, depending on the particular application and the down-
strearn position of the ~articular back-up roller 133~
If desired, in order to mitigate slightly the
rigidity of tile opposing convexly bowed rigid back-up rollers
34, slightly compliant spacers 101 may be mounted between the
support members 50 and the rigid lower headers 38.
In order to assure that the positions of the rigid,
convexly bowed back-up rollers 34 are accurately predetermined
relative to the casting region C, the lower carriage frame 21
and the lower headers 38 and longitudinal stringer members 50
are constructed to be as rigid as prac~icable.
So far there has been described methods and systems
which involve predetennination of the desired bowability.
Now there will be described methods and systems which are
adjustable at will, even being adjustable while the castin~
machine 10 is running.
MET~ODS AMD SYSTEMS FOR SHAPING THE CASTING R~GION
PROVIDING ADJUSTA~ILITY
_ _ ~
In order to elastically bend the flexible, bowable
back-up rollers 133 for supplying adjustable forces toward the
casting belts and hence toward the casting region C, approxi-
mately equal and opposite couple-forces are applied to non-
rotating, lever-like, stuh-shaft extensions 63 of the bowable
back-up rollers 133 as shown in FIGS. 10 through 15 and 17
through 19.
-25-
As shown in FIG. 12A, the bowable back-up rollers
133 are connected to the s-tub-shaft extensions 6~ by a pair
of axially spaced anti-friction bearings 67 located in a bearing
assembly 77 located within a larye end portion 79 of the roller
133. The two bearings 67 are axially separated by a spacer
sleeve 83 and are mounted upon an inner sleeve 85 on the
stub~shaft extensions 63. The space between these sleeves
83 and 85 may be used to hold grease for the two bearings 67.
In order to provide an effective pivot point (i.e.
a fulcrum) for the lever-like stub-shaft 68, there is a
hardened steel collar or housing 72 seated in a drill hole
in the respective carriage frame 19 (or 21 as the case may be)
held by a set screw 74 and having an internal shoulder 86
which acts as a fulcrum for the stub-shaft lever 68.
Therefore, adjustably moving the outer end of the stub-shaft
lever 68 applies a couple-force (i.e. a bending moment) to the
flexible back-up roller 133 for bowing it as desired. Although
the fulcrum is actually located at 68, the effective pivot
point may be considered to be located at 86A on the axis of
the stub-shaft lever.
An approximately equal and opposite-sense couple-forc~
(bending moment) is also applied to the opposite end of the
flexible roller. By virtue of the couple-forces (bending moments)
applied by the levers 68 to the ends of bowable roller 133 a
constant moment is applied throughout the length of the roller;
that is, if this roller 133 were o-therwise free, its axis would
be bowed into a circular arc. The stub shaf-ts may alternatively
be extended into shafts passing a]l the way through the roller,
as shown in FI~S. 10 and 11.
-26-
As sho~Jn in ~IG. 10 the stub-sha~t levers 68 for the
upper bowable back-up rollers 133 have actuating levers 78
connected to their outer ends. Each such actuating lever 7~
is driven by adjustable means 80 shown as a horizontally po-
sitioned tightening machine screw which screws in-to a socket
in t'ne side of the machine frame 19. The stub-shaft lever 68
has a fulcrum 86 provided by a collar or housing 72.
The lower back-up rollers 134 are bowable, having
self-aligning bearings 59 and fixed stub shafts 70. In
the downstream portion of the casting region C where the ~etal
in the casting region C is mostly all solidified, the flexible
back-up rollers 134 conform to the thickness of the cast product.
Therefore, the adjus-tment of the adjusting means 80 will tend
to establish the arc of transverse curvature of the casting
region C and will cause both belts 12 and 1~ to hug the product
for achieving good and uniform heat transfer over the areas of
bot:h top and bottom surfaces of the solidifying productO
In the upstream and central portions of -the casting
region C, where more of the metal is still molten, the "head"
of the molten metal will cause predeterminable bending of
the lo~er flexible rollers 134. The back-up-roller-bowing
adjustment means 80 therefore are initially adjusted to provide
a bow in each successive upper roller 133 which will correspond
with the predetermined anticipated bow of the opposed lower
roller 134. During operation of the casting machine the
opera-tor may then further adjust the adjusting means 80 if
desired for further modifying the shape of the casting region
C at: the location of each adjustable back-up roller 133.
-27-
~ 3 Y ~
In the upstream and central portions of the casting
reyion C the bowing of the adjustable roller 133 may,if desired,
be made slightly less than the anticipated predetermined bowiny
of the lower rollers 134 for providing a transverse contour of
the casting region C which is very slightly thicker near the
middle as compared with the thickness of the margins near
each edge darn 28. This slightly thicker middle then compensates
~or subsequent shrinkage of the middle of the cast product as
it solidifies and cools below its freezing temperature.
The back-up roller bowing method and system of FIG.
11 are similar to those shown by FIG. 10, except that the
fulcrum 86 is fo~ned by the juncture o~ a conically tapered
outer section of the stub-shaft lever 68 and a cylindrical
inner section of this stub-shaft lever. Consequently, the
hardened s-teel housing or collar 72 does not include an inAer
shoulder, and this housing or collar is extended out beyond
the side of the frame 19. The adjusting means 81 is a vertically
extending machine screw whose shank extends down through a
hole in the wall of the cylindrical collar or housing 72.
This adjusting screw 81 screws into a threaded hole in the outer
end of the conical outer section of the stub-shaft lever 68.
Thus, by tightening up on the two ad~usting screws 81, the a~is
of the bowable back-up roll 133 is bowed conve~ly down toward
the casting region C.
The back-up roller bowing method and system of
FIGS. 12 and 12A are similar to those of FIG. 11, except that
the adjusting means 82 is a longer screw -than the screw 81, so
that compliance means 84 is included in the adjus-tment. This
compliance 84 is provided by a compression spring which surrounds
the screw shank and is compressed between a washer beneath the
-28-
~2373
heac!of screw 82 and a washer seated on the wall of the cylindric~l
housing or collar 72. The threaded lower end of the screw
shank screws into a threaded hole in the outer end of the conical
outer portion of the stub shaft lever 68. Among the advantages
of including this compliance 84 which modifies the adjustment
effect of the screw 82 are those resulting from the fact that
a smaller gradiant of adjustment is afforded than with the
direct (non-compliant) adjustment means shown in FIGS. 10 and
11. In other words, with the same screw thread pitch, a given
amount of turning of the screw 8Z will cause less bowing of the
axis of the roller 133 than with the screws 81 or 80. The
compliance of the springs 8~ is predetermined to have a range
comparable with the bowing compliance of the roller 133 as
coupled through (reflected through) the stub-shaft levers 68 to
the respective springs 84. At locations along the casting region
where proportionately more bowing of the rollers 133 is
desired, somewhat stiffer springs 84 may be employed.
Another advantage of using these compliant means 84
is that they will allow the castina belt 12 to deflect or yield
for avoiding damage in case a prematurely solidified chunk of
metal passes through the casting region C having a size greater
than the spacing between the belts 12 and 14.
In FIG. 12 the fulcrum 86 is provided by the
conical/cylindrical junction on the stub-shaft le~er 68. In
FIG. 12A this fulcrum 86 is provided by an internal shoulder in
the collar or housing 72, as previously described. If desired,
-29-
as shown in FIG. 12A, the threaded lower end of the shank of the
screw 82 is extended down through a second hole in the wall of
the housing or collar 72, so that an adjustable lock nut 88 may
be used to prevent inadvertent "creep" of -the adjusted position
of the adjusting screw 82.
As shown in FIG. 13, in order to provide remote
control of the adjustment of the back-up roller bowing, there are
fluid-actuated cylinder and piston units 90 whose piston rods 91
are pivotally connected to the respective outer ends of the stub-
shaft levers 68. There are a pair of pipe lines 92 for fluid,
connected to the upper and lower ends of the cylinder units 90
~or operating the piston therein. Preferably these units 90 are
hydraulic units; however, pneumatic cylinder and piston units
90 may be used, if desired.
The use of pneumatic units will inherently provide
compliance by virtue of the compressibility of the compressed
air in the cylinder 90. In order to provide compliance in the
remote control system when hydraulic liquid is used as the
actuating fluid, check valves are omitted from the pressure
regulating valves, which are set at the desired pressure in the
cylinder and piston units 90 corresponding to the predetermined
desired bowing of the back-up rollers 133.
Actuatio.n of these units 90 pulls upwardly on the
piston rods 91, thereby controllably bowing the axis of the
roller 133 convexly down toward the casting region C~ A remote
~3~-
3~3
con-trol console (not shown~ is located near the operator's
station including display meters providing a read-out of the
pressure in the eontrol units 90 for each bowable back-up roller.
The console display meters may also be calibrated in thousandths
of an inch or hundredths of a millimeter for indicating the
con-trolled bowing of the mid-point of the axis of each roller
133 away from a straight line. In other words, the pressure in
each suceessive pair of units 90 for eaeh suceessive bowable
roller 133 along the casting region C can be independently
controlled, and the resultant amount of defleetion of each roller
can be xead on the read-out displays of the console.
The method and system for adjustably bowing the back-
up rollers 133, as shown in FIG. 14, are similar to those shown
in FI~S. 12 and 12A in that compliance springs 84 are associa-ted
with the adjustment serews 82 for bowing the flexible baek-up
rollers 133. The lower back-up rollers 34 are of rigid
three-section eonstruetion with longitudinal stringer support
members 50 mounted on r.igid transverse frame members 38, for
example, whieh may be the coolant headers as explained above.
~he upper back-up rollers 133 are being bowed convexly toward the
casting reyion ~.
In order to eause the axis of -the bowed rollers 133
to have a flatter (longer radius) arcua-te curvature opposi-te
the middle of the easting region C for causing the upper belt 12
to hug the solidifying metal opposite the rigidly backed-up
belt 1~ which has a straight transverse shape, the di.ameter of the
-31-
~,~ /3
micldle shaft portion 96 of the hollow bowable roll shaft is
macle larger than the end shaft portions 94. The diameter
of the bore o~ this hollow roller 133 is uniform. Therefore,
the ~all thickness of the middle shaft portion 96 is proportionate
ly increased more than the difference in the outside diameter of
the middle shaft portion 96 as compared with the outside diameter
of the end shaft portions 94. (It is noted that the stiffness
of a lenqth of round solid shaft in bending varies as the fourth
power of its diameter.) Consequently, the stiffness of the
hollow middle portion 96 in bending varies as a higher power
function of its outside diameter than in the case of a solid shaft
~s a result, relatively small increases in outside diameter of
the middle portion 96 of this hollow shaft will provide relatively
large increases in stiffness as compared with the hollo~ end
portions 94.
It is to be understood that the differences in dia-
meter at 96 and 94 r as shown in this FIGURE and in FIG. 15, are
exaggerated for purposes of illustration, and the bowing of the
roller 133 is also exaggerated. The solidifying product
in the casting region C is sho~n in FIGS. 1~ and 15 as having
shrunk slightly relative to the height of the edge dams 2~. (Not
only is the cast prod~lct cooling and shrinking, but the solid
metal blocks in the edge dam 28 are becoming heated and are
expanding.~ This shrinkage relative to the e~panding edge dams 28
is indicated exaggerated at the upper surface of the margins of
the cast produc-t at 97. The ob~ective of the more flexible end
shaf-t portions 9~ is -to bow the back-up roller 133 down~ardly
-32-
~23~
for causing the upper belt 12 to hug the shrinkiny cast product
as close to the edge dams 28 as possible.
The method and system for bowing the back-up rollers
133 in FIG. 15 is similar to that described above in FIG. 14,
except that remotely controllable fluid-actuated cylinder and
piston units 90 are employed, thereby providing similar operating
an~d control advantages as explained in connection with FIG. 13.
In FIG. 16 the casting region is shown selectively
tapered toward the downstream or exit end 31. The casting
region is labelled "C or CB" for indicating that this casting
region may be relatively wide as illustrated in FIGS. 6, 9-15,
17, 20-24 or may be relatively narrower and higher for casting a
bar product as illustrated in FIGS. 18 and 19. The molten (liquid
metal is indicated dotted at 125, and the soli.dified (frozen)
metal is indicated by diagonal cross-hatching lines at 135.
The ca~t product P travels away from the cas-ter exit 31 carried
by appropriate conveyor means (not shown), and secondary cooling
means (not shown) are often employed for further cooling of the
cast product P as immediately as possible after exiting from the
caster D
It .is to be noted that the molten interior reyion
125 of the solidifying product 135 continues downstream along a
considerable distance approaching toward or even extending beyond
the exit 31. This molten interior 125 may be called the molten
or "liquid core" or "liquid sump"~ Generally speaking, for a
given thlckness of cast product P, -the fas-ter the caster 10 is
running, the further downstream extends the interior liquid sump
-33-
973
125. In practically every case where the liquid sump 125 extends
downs-tream beyond the exit 31 secondary cooling is employed.
The casting region C or CB is shown longitu~inally
divided into an upstream portion or zone 102, a central portion
or zone 104, and a downstream portion or zone 106. In this
upstream portion or zone 102, the rigid back-up rollers 134 and
the flexible back-up rollers 133 hold the casting belts 12 and
14 generally parallel. In this upstream portion 102, very slight
excess (or bulging3 in thickness (as seen in transverse section)
may be provided in the major central transverse area of the
casting region C or CB ti.e. the transverse contour of the casting
region C or CB may be very slightly.thicker over the ma~or central
portion of its area) as compared with the margins, because the
margins of the cast metal 135 adjacent to the edge dams tend
to solidify and cool more ~uickly than the major central area of
the cast metal for thereby compensating for the subsequent
shrinkage in this major central axea tas seen in transverse
section).
In the longitudinal central portion or zone 104
of the casting region C or CB the belts 12 and 14 begin to
converge slightly downstream, i.e. the mold space is tapered
by the rigid lower back-up rollers 34 or flexible lower back-up
rollers 134 or 108 (FIG. 18) in cooperative action in opposition
to the -flexible upper rollers 133 or 107 (FIG. 18).
The flexible back-up roll.ers may be bowed r adjusted
and controlled in their belt contour configuration in the
~34-
~9~3~
respective zones 102, 104 and 106 by any one or more (singly or
jointly) oE the various methods and systems as described above,
or as described hereinafter. The longitudinal taper through
the various zones 102, 104, 1¢6 may be varied and may be utilized
for achieving various transverse contours as desired for
causing both belts to hug the solidifying metal 135 and for
producing a cast product P of the desired dimensions and desired
uniform metallurgical properties.
In the longitudinal downstream portion or zone 106
of the casting region C or CB, the belts 12 and 14 converge with
an increased taper as compared with the zone 104 as achieved by
the rigid lower rollers 34 or flexible lower rollers 134 or 108
~FXG. 18) in cooperative action in opposition to the flexible
upper rollers 133 or 107 (FIG. 18~.
The "head" pressure effect against the belts may be
greatest in the zone 10~ or in the zone 106 depending upon such
factors as the amount of solidified metal 135 as compared with
liquid sump 125, speed of the caster 10, density (weight per unit
volume) of the molten metal 125, overall thickness of the
product P.
I desired r the downstream taper of the longitudinal
zones 104 and 106 may be accomplished in par-t by causiny the
upper carriage U to converge downstream slightly toward the
lower carriage by using compliant gauge spacers 121 (FIG. 26) or
128 (FIG. 27) between the side members of the carriage fram~s l9
and 21 near the exit end 31 in lieu of the rigid gauge spacers
17 (FIG. 1)~ Thus, rigid gauge spacers 17 are used near the
-35-
upstream end 11 and compliant ones 121 or 128 (FIGS. 26 or 27)
are used near the downstream end 31. Therefore, the downstream
end of the upper carriage U may be caused to "float" somewhat
upon the "head" pressure of the liquid sump 125 acting against
the area of the upper belt.
In FIG. 17 the remotely controllable fluid-actuated
cylinder and piston units 90A are connected between the stub-shaft
levers 68 for applying essentially equal and opposite force-
couples ~bending moments) to the respective opposed bowable
lower and upper rollers 134 and 133. The piston rods 91 are
detachably pivotally connected to the respective lower stub-
shaft levers 68~
The circumferential ridges or fins 55 are shown
more closely spaced at 55A (FIG. 17) near the margins of the
casting region C, thereby providing the operator with the
option of positioning the edge dams 2~ closer together. It is
desired that the fins 55A be relatively close together for firm
back-up of the respective belts where the edge dams are located.
In the modification shown in FIG. 17~ the closely
spaced fins 55B opposite the edge dams 28 have a reduced diameter
as compated with the other fins 55 on the same back-up roller
opposite the casting region C. These reduced diameter fins 55B
allow the laryer fins 55 to push the respective belts 12 and
14 inwardly for causing the belts to hug the solidifying shrinking
metal at the margins 97 as close to the edge dams as possible~
This reduced diame~er fin modiflcation of FIG. 17A
-36-
9;~3~3
can be used to advantage in the zone 106 (FIG. 16) and may be
used in the zone 104 (FIG. 16) if desired. This reduced diameter
fin modification can be used to advantage in conjunction with
the increased flexibility of roller end sections 94 (FIGS. 14
and 15).
FIGURES 18 and 19 show the casting of a bar product
and so the casting region is labeled "CB." The internal liquid
sump 125 is shown, and this liquid sump is smaller in FIG. 19,
because FIG. ]9 iS a section taken farther downstream than FIG.
18. The edge dams 28 are shown higher than in previous FIGURES,
because a bar product is cast relatively thicker.
In order to compensate for the shrinkage ~7 of the
solidified metal (FIG.;19) the lar~q end portions 79A (FIG. 19)
of the upper and lower bowable back-up rollers 107 and 108 are
made smaller in diameter than the normal-sized fins 55. (These
large end portions 79A may include one or more grooves 123 for
allowing coolant to flow along the belt.) The resulting belt
clearance spaces at the edge dams permit the fins 55 to deflect
the belts slightly to hug the shrin~.ing produc~ very effectively
for minimizing any shrinkage gap 97 at the margins adjacent to
the edge dams 28. Indeed, such reduced-diameter techniques of
relief effectively permit roller-bending or taper to be used
downstream.
In FIG. 18 the large end portions 79 are shown to
have the same diameter as the fins 55.
For providing the fulcrums 86, the shaft housings 72
project inwardly from the side members of the respec-tive carriage
frames 19 and 21 and include internal shoulders formed by
hardened steel ring inserts.
-37
The remotely controllable fluid-actuated cylinder
and piston units 90B for bowing the rollers 107 and 108 are
pairs o~ cylinders located on opposite sides of the lower
stub-shaft levers 68. In other words~ this pair of cylinders
straddles the lever 68. These pairs of cylinders are mechanical-
ly interconnected by a yoke structure 127 having a hardened
steel ring insert 129 forming the outer pivot fulcrum for ~he
lower stub-shaft lever 68. The pairs of piston rods 91 are
also interconnected by a yoke structure 137 having a similar
ring insert forming the outer pivot fulcrum for the upper stub-
shaft lever 68. The advantage of straddling the stub-shaft
lever 68 is that longer cylinder units 90B can be employed more
conveniently for a greater range of cast thicknesses. The
advantaye of the modified design with its greater leverage and
heavier parts is that it permits more effective roller-bending
for narrow cast products. Equal and essentially opposite
force-couples (bending moments) are advantageously being applied
to both the upper and lower rollers 107 and 108 for a~hieving
symmetrical upper and lower belt contours~
In the embodiments described above, -the belt shape and
contact control has been primarily accomplished by directly bowing
flexible back-up rollers 133, 134, 107, 108 in various ways.
Another system which is shown in FIG. 20 involves the elastic bend
ing of a relatively rigid structural frame member 112 having rela-
tively rigid back-up ro]lers 33 mounted there-to by the stringer
members 52, so that these segmented rollers 33 also will be caused
to assume an overall arcuate configuration.
~--
In FIG. 20, the transverse frame member 112,
which for example may be a header or o-ther frame member, is stiff-
ly bowable. It has upstanding arms 116 at either end. A trans-
verse xod 120 is mounted in the frame 19 of the upper carriage U
having tightening nuts 115 on threaded end regions of -this rod.
In this embodiment by tightening the nuts 115, the frame member
112 is bowed and since the back-up rollers 33 are slaved to this
frame member, the back-up rollers 33 also bow a corresponding
amount. The lower back-up rollers 134 are bowable under the
pressure of the metal "head".
In FIG. 21, which is similar to FIG. 20, a
transverse member is positioned generally parallel with the
stiffly flexible frame member 112. This second member 110 is
more flixible than the first member 112, for examp:Le, it is a
bowable leaf spring member. This second member 110 is attached
by bolts 119 to the ends of the first member 112 with a center
spacer or block 114 positioned therebetween. By tightening the
bolts 119 at the ends of the bowable leaf spring member, the
first member 112 is bowed as is the segmented upper back-up
roller 33 which is rigidly attached *o the latter by the stringer
members 52. By utilizing this second member 110, which has more
flexiblity than the first member 112, a finer, more determinate,
vernier bowing adjustment can be made of the transverse frame
member 112 and hence more determinate bowing of the confiyuration
of the back-up roller 33.
-39-
37~
In FIG. 22 a remotely controllable fluid-actuated
cylinder and piston unit 117~is pivotally connected at 139 to a
bracket 109 mounted centrally on a lower stiffly flexible -trans-
verse frame member 112, for example, which may or may not be a
coolant header. Thus, a remotely controllable bending moment is
applied for bowin~ this transverse frame member 112 whose ends
are captured by flanges at 113 and retainers 141 bolted to the
lower frame 21. Accordingly, as the member 112 is bowed, the
segmented, rigidly mounted back-up roller 34 is correspondingly
bowed to urge the lower belt 14 against the cast metal. The
upper back-up roller 133 is bowable, so that the upper belt 12
stays in contact with the top surface of the cast metal.
In the embodiment illustrated in FIG. 23 a
combination of the transverse frame bowing methods and sys-tems
utilized in FIGS. 21 and 22 is employedO Accordingly, the
upper back-up roller 133 is bowable. The lower segmented back-up
~oller 34 which is rigidly mounted to the lower frame member 112 is
also bowed by actuating the centrally located cylinder unit 117
which is secured by mounting means 143, for example bolts, upon a
second, generally parallel, more flexible transverse member 110,
fox example, a leaf spring member, whose ends are also captured
by the retainers 1410 In effect, the remotely controllable unit
117 is drawing a bow by pushing up on the stiffly flexible member
112 while pulling down upon the relatively more flexible second
member 110. Therefore, the remotely controllable unit 117 in
~40-
~923'73
.. _
I'IG. 23 provides an accurately determi~ate bowing of the first
frame member 112 for precisely controlling the configuration
of the roller 34 which is rigidly slaved to the member 112.
FIG. 24 shows a method and system for controllably
bowing rollers 34 generally similar to FIG. 23, except that a
pair of remotely-controllable fluid-ac-tuated units 118 mounted
on the lower carriage frame 21 are pivotally connected at 111
to the respective ends of the second member 110. A spacer
block 114 is located between the central regions of the first
and second members 112 and 110, respectively.
In order to simultaneously bow a plurali-ty of
transverse frame members 140, for example, headers, there is
a longitudinally positioned rocker arm 136 whose upstream end is
effecti~ely pivoted at 142 by a fulcrum connection to the frame
19 of the upper carriage U. ~ remotely controllable fluid-
actuated cylinder and piston unit 138 is secured to the frame 19
in the vicinity of the downstream end of this rocker arm 136.
The rocker arm 136 and the cylinder unit 138 are located midway
between the inboard and outboard sides of the upper carriage U.
Its piston rod 91 urges the downstream end of this rocker arm 136
for bowing the transverse frame members 140 convex down toward the
casting region for producing a corresponding convex down
configuration of the upper bac~-up rollers 33 which are slaved
to the respective transverse frame rnembers 140. The opposed
lower back-up rollers 134 are bow~ble.
-41--
Each successive transverse frame member 140 is
bowed slightly more than its upstream member, because each
successive frame member 140 is being acted upon by the rocker
arm 136 further downstream from its pivot fuIcrum. Thus, a
remotely controllable taper of the casting region C is advantage-
ously provided by actuating the unit 138 acting through the
rocker arm 136.
The compliant gauge spacer 121 ~FIG. 26) includes a
head 122, a locating pin 124 which engages i.n a socket 144 in the
side frame member of the lower carriage 210 This loca-ting pin
124 is screwed into the head 122 with a plurality of Belleville
washers (conical spring washers) 126 on the shank of this pin.
These spring washers are captured by a shouIder 146 on the
locating pin 124. The lower surface of the head 122 has a concave
conical shape 148 with a pitch or slope which is more shallow
than the pitch or slope of these spring washers when they are in
their unloaded (relaxed) condition, and thus there is a gap 131
for permitting compliant de-flection of these spring washers up
~o a limit when this gap 131 is closed. Hence, the slope of
concave surface 148 acts as a stop for limiting the deflection
of these spring washers to a predetermined limit.
The compliant gauge spacer 128 (FIG. 27) has a head
122 and a locating pin 124 insertea into a socket 144. The
locating pin 124 is fastened by a small diameter stud 130 passing
through a small diame-ter hole 150. A sti:Efly flexible leaf
spring 152 is thereby captured on the stud 130. The deflection of
-42-
~23~
this leaf spring 152 is limited by the gap at 132. A retainer
pin 154 seated in a socket in the side frame 21 engages in a
notch 156 for holding this leaf sprin~ in longitudinal alignment
with -this side frame.
It is to be noted that the bearing assemblies 77
(FIG. 12A) can be inverted (turned inside out) by using hollow
cylindrical stub shafts which encircle the bearings 67 which,
in turn, encircle the end o~ the roller shaft 63.
Also, it is to be noted that in FIGS. 6, 8 and 9,
the transverse members 38 and 46 can be othe.r members than
headers.
Since other changes and modifications, varied
to fit particular operating and casting requirements and
environments, will De understood by those skilled in the art, the
invention is not considered limited to the examples chosen for
purposes of illustrati.on, and i.ts scope includes all changes
and modifications which do not constitute a departure from the
true spirit and scope of this invention as claimed in the
following claims and reasonable equivalents to the claimed steps
and elements.
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