TWIN ROLL CASTER AND METHOD OF CONTROL THEREOF
BACKGROUND AND SUMMARY OF THE INVENTION
This invention relates to the casting of metal
strip by continuous casting in a twin roll caster .
In a twin roll caster, molten metal is introduced
between a pair of counter-rotated casting rolls that are
cooled so that metal shells solidify on the moving roll
surfaces and are brought together at a nip between them.
The term "nip" is used herein to refer to the general
region at which the rolls are closest together. The molten
metal may be poured from a ladle into a smaller vessel or
series of smaller vessels from which it flows through a
metal delivery nozzle located above the nip, forming a
casting pool of molten metal supported on the casting
surfaces of the rolls immediately above the nip and
extending along the length of the nip. As the molten metal
formed in shells are joined and passes through the nip
between the casting rolls, a thin metal strip is cast
downwardly from the nip .
The casting pool is usually confined between side
plates or dams held in sliding engagement with end
surfaces of the casting rolls so as to constrain the two
ends of the casting pool against outflow. Side dams at the
ends of the casting rolls prevent leakage of molten metal
from the casting pool and maintain the casting pool at a
desired depth. As the casting rolls are rotated, the side
dams experience fractional wear, causing arc-shaped
grooves to form in the side dams along the circumferential
surfaces of the casting rolls . In order to compensate for
this wear , the side dams are movable to gradually shift
inward under compression forces in order to maintain the
seal with the casting rolls .
The useful life of a side dam has traditionally
been limited by the depth of the arc-shaped grooves that
can be made without risk of solidified sculls forming and
dropping through the nip between the casting rolls and
forming defects, called "snake eggs," in the cast strip.
It has all been proposed to increase the life of the side
dams by making them vertically moveable so they can be
moved upward. That way multiple arc-shaped grooves can be
worn into the same side dam. thereby increasing the useful
life of the side dam. Examples of these past proposals for
increasing the useful life of side dams are described in
U.S. Patent No. 7,066,238 and U.S. Patent Publications
Nos. 2006/0054298 and 2010/0101752. However, there
continues to be a need for a way to improve the
operational life of side dams .
In any event, the arc-shaped grooves tend to
promote the formation of solidified sculls in the molten
metal that tend to cause the formation of snake egg
defects in the cast strip. Where the side dams engage with
the ends of the casting rolls , the amount of cooling of
the metal shells on the casting rolls is higher than in
the center of the rolls . The solidified sculls can form in
solidified shells adjacent the side dams in the arc-shaped
grooves and may give rise to snake egg' defects in the
formed metal strip. Such snake eggs can cause not only
defects in the cast strip but may also cause the
continuous metal strip to break or otherwise rupture as
the strip is formed. Accordingly, there remains a need for
a twin roll caster, and method of operating the same, that
reduces the likelihood of formation of snake eggs by
inhibiting the formation of arc-shaped grooves in the side
dams adjacent the casting rolls, while extending the
operating life of the side dams .
The above description is not a description of the
common general knowledge .
Disclosed herein is a twin roll caster
comprising :
a pair of counter-rotatable casting rolls having
casting surfaces laterally positioned to form a nip there
between through which thin cast strip can be cast, and
supporting a casting pool of molten metal on the casting
surfaces above the nip:
a pair of side dams positioned to engage end
portions of the casting rolls adjacent the nip to
laterally confine said casting pool : and
a side dam support applying a compression force
against at least one of said side dams at an upward angle
between 15°and 45° relative to an axis of said casting
rolls.
The side dam support may be provided at each end
portion of the casting rolls by applying an angular
compression force against each side dam at an upward angle
between 15°and 45° relative to the axis of each of said
casting rolls. In any case, during operation said side dam
is worn by said end surfaces of said casting rolls to form
a slantwise groove in each side dam. The slantwise groove
may be in the form of a V-shaped arcuate groove.
The side dam support may comprise a lateral
pushing apparatus to push said side dam against said end
surfaces and a vertical pushing apparatus to adjust the
height of said lateral pushing apparatus . The lateral
pushing apparatus and the vertical pushing apparatus may
be adapted to operate at the same time .
In addition, a control device may be adapted to
control said vertical pushing device and said lateral
pushing device to provide a target compression angle.
Alternatively, the side dam support may comprise a
slantwise pushing apparatus adapted to push said side dam
against said end surfaces of the casting roll at a target
compression angle . The compression angle may be
dynamically controlled.
Also disclosed is a method of controlling a twin
roll caster having two laterally positioned casting rolls
forming a nip there between and two side dams positioned
adjacent opposite end portions of the casting rolls to
enable a casting pool to be formed on the casting rolls
above the nip, the method comprising the steps of:
providing a compression device to apply a
compression force against said side dams inwardly towards
end portions of said casting rolls at an upward angle, and
applying the compression force against said side
dams and forming slantwise grooves worn in the side dams
by said end portions of said casting rolls .
The method of controlling the twin roll caster
may include causing the compression device to apply the
compression force to form slantwise grooves as a series of
V-shaped grooves by the steps of determining a target step
thickness and spread angle for V-shaped grooves, and
controlling the compression device to provide the
compression angle to provide said target step thickness
and said spread angle in the side dams.
The method may include providing a lateral force
parallel to an axis of said casting rolls and a vertical
force perpendicular to said lateral force to form a
resultant compression force at said compression angle.
The method may include providing a control device
to determine said compression angle and communicate with
said compression device to adjust said compression angle.
The compression device may be a slantwise compression
device to provide said compression force at said
compression angle . The slantwise compression device may
also include an angular adjustment member for adjusting
said compression angle.
Also , said slantwise compression device may
include a displacement measuring device . The further
steps may include communicating a displacement value from
said displacement measuring device to the control device,
determining a target compression angle based on said
displacement value and a target spread angle, and
communicating a value to said angular adjustment member to
adjust said slantwise compression device to said target
compression angle. Said spread angle may be either
variable or fixed.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a side view of a twin roll caster
system according to one embodiment of the invention .
FIG. 2 is an end section view of the twin roll
caster system of FIG. 1 taken along line 2-2 in FIG. 1 .
FIG. 3 is an enlarged section view of side dams
taken along line 3-3 in FIG. 2 .
FIG. 4 is an enlarged section view of the side
dams taken along line 4-4 in FIG. 2 .
FIG. 5A is an alternative view of the section
taken along line 2-2 in FIG. 1 .
FIG. 513 is a section view of the side dam and
casting rolls taken along line B-B in FIG. 5A.
FIG. 6 is an alternative arrangement of the
section view of FIG. 5B taken along line B-B of FIG. 5A.
FIG. 7 is a side view of the twin roll caster
system of FIG. 1 according to an alternative arrangement.
FIG. 8 is a side view of the twin roll caster
system of FIG. I according to an alternative arrangement.
FIG. 9A is a top view of a prior art twin roll
caster system.
FIG. 9B is a top view of the prior art twin roll
caster system of FIG. 9A showing the wear pattern of the
side dam.
DETAILED DESCRIPTION OF DRAWINGS
A twin roll caster system 100 is generally shown
in FIG. 1 . According to the embodiment illustrated, the
twin roll caster system 100 includes first casting rolls
102 and second casting rolls 104 positioned laterally to
one another forming a nip or gap G between them. At
opposite ends of the casting rolls 102, 104 are positioned
side dams 106, thereby defining a pool P for receiving and
forming casting pool P on the casting rolls 102, 104 above
the nip. One or more delivery nozzles (not shown) are
positioned above the casting rolls 102, 104 between side
dams 106 to deliver molten metal into the casting pool P
in a continuous supply during casting. The side dams 106
are urged against the casting rolls 102, 104 by inward
biasing forces to provide a tight seal in order to prevent
molten metal from leaking from the casting pool P .
Compression devices 108 are provided to engage the side
dams 106 and provide the inward biasing force against the
casting rolls 102, 104.
During a casting campaign, the first casting roll
102 and the second casting 104 are rotated in opposing
directions towards the gap G to cast metal strip 111
having a predetermined thickness corresponding generally
to width of gap G downwardly from the gap G . The casting
rolls 102, 104 are internally cooled so that as they
rotate through the casting pool P of molten metal and thin
shells of solidified metal are formed on the rolls 102 ,
104. The side dams 106, as a consequence of being biased
against the rotating casting rolls 102, 104, will
experience gradual wear, resulting in arcuate shaped cut
aways formed by abrasion in the side dams .
According to one embodiment, compression devices
108 each apply a lateral force FL (inwardly in the
direction of the axes of the casting rolls 102, 104). An
upward vertical force (perpendicular to the lateral FL) is
also applied on the side dams 106. The vertical force is
applied by vertical drives 112 acting against compression
devices 108. Upward vertical force Fv is accordingly a net
force equal to the vertical force generated by each
vertical drive 112 less the force attributable to lifting
the compression drives 108. The combined resultant force Fc
causes each of the side dams 106 to move inward and upward
as the side dams 106 are abraded by casting rolls 102, 104
to form arcuate cut-aways 109. As a result, arcuate shaped
cut-aways 109 are formed typically with V-shape grooves
110 as shown in FIGS. 3 and 4 , which extend and spread
away from the side dams 106. These slantwise, i.e. angled,
grooves 110 allow for an increased flow of molten metal
over the arcuate gaps C inhibiting the formation of the
sculls and enabling consistent and effective casting of
metal strip during the casting campaign.
As shown in FIG. 1 . the compression devices 108
each may have a hydraulic cylinder that engages one of the
side dam 106 and applies a lateral force FL , urging the dam
106 inwardly toward the ends of the casting rolls 102.
104. Vertical drives 112 provide a vertical force which
nets as an upwardly vertical force Fv on the side dams 106
through the compression devices 108. As shown in FIG. 1 ,
each of these vertical drives 112 may include a screw jack
114 which adjusts the height of a compression device 108.
The screw jack 114 may advance the compression device 108
upwardly along guide members 116, such as slide rails or
similar guides as shown in FIG. I .
Those having skill in the art will appreciate
that the lateral FL and vertical F forces may be applied
independent of one another. However, as shown, the lateral
FL , and vertical Fv forces combine to apply a resultant
compression force Fc at an upward angle g against the
casting rolls 102, 104. The magnitude and angle of the
resultant compression force F is variable and changes
based on the magnitudes of the lateral FL and vertical F
forces . Because the lateral FL and vertical forces F may
be independently controlled (lateral force by the
compression device 108 and vertical force by the vertical
drive 112) , the angle and magnitude of the compression
force F may be dynamically variable .
FIG. 2 shows a side view illustrating the
location of the side dams 106 relative to the casting
rolls 102, 104. The double dashed lines in this side view
show a first position 106' of upper portions of the side
dam 106 and the solid lines show a second position 106" of
upper portions of the side dam 106 after it has been
advanced by one of the vertical drives 112. The dashed
lines illustrate the location of the side dams 106 when
the casting rolls 102. 104 engage and begin to abrade the
side dams 106. As will be appreciated, as the side dams
106 are abraded by the end surfaces of the casting rolls
102, 104, the side dams 106 are shifted upwardly, thereby
moving the arc-shaped cut-way 109 away from the casting
rolls 102, 104 as shown by arc-shaped cut-away 109' shown
in FIG. 2 .
FIG. 3 illustrates a side view of one of the side
dams 106 taken along line 3-3 in FIG. 2 and FIG. 4 is a
side view taken along line 4-4 in FIG. 2 . According to the
embodiment illustrated in these figures, each of the side
dams 106 includes an unworn portion 118 that extends into
the space between the casting rolls 102, 104 as the side
dam 106 is abraded, forming arc-shaped grooves 110.
Because the side dams 106 are independently adjusted in a
vertical and horizontal direction, these grooves 110 will
be V-shaped, as the unworn portion 118 of the side dam 106
is moved inward and upward away from the casting rolls
102, 104. As shown in FIG. 4 , the V-shaped grooves 110
will extend at a spread angle x away from the casting roll
102. Therefore, the side dam 106 will include an abraded
portion 120, an unworn portion 118, and a slantwise
portion extending at 90°+ a from the abraded 120 to unworn
portion 118. The spread angle a and the thickness X of
this slantwise portion may be determined by the lateral FL
and vertical Fv forces as described herein with reference
to FIGS. 1 and 4-5. Alternatively, the spread angle a and
the thickness X may be set and the lateral FL and vertical
Fv forces may be adjusted to produce the desired spread
angle a and thickness X .
According to alternative embodiments, the spread
angle a and the thickness X of the arc-shaped grooves 110
may vary during the casting campaign causing the grooves
110 to have a non-linear V-shape or stepped shape or
include one or more different spread angles a and
thicknesses X during different segments of the casting
campaign , and may be concave , convex , even and uneven Vshaped
steps , or some combination thereof .
In FIG. 1 , a control device 122 is provided that
calculates the amount of lift Y that is to be provided by
each of the vertical drives 112 for a given thickness X
and spread angle a of the slantwise groove and is given by
the formula :
As discussed above, the thickness X and the
spread angle a are provided based on the desired shape of
the slantwise grooves 110 and may vary over time. The
angle b is based on the height of the casting pool P along
a vertical measurement PL from the center of the casting
roll 102 (shown in FIG. 5A) and the radius (also D/2) of
one of the casting rolls 102. The angle b is given by the
formula :
Therefore, to calculate the amount of lift Y
provided by each of the vertical drives 112, the control
device 122 must receive as input the desired spread angle
a , the displacement X of the compression devices 108, the
pool height PL and the radius R of the respective of the
casting rolls 102. These values are used to calculate the
desired lift Y that will result in the desired spread
angle a . The desired displacement X of the compression
devices 108 is provided by means of an input signal 124
from the compression devices 108 to the control device
122 . The control device 122 then processes this
information and sends a command signal 126 to the vertical
drives 112 to provide the appropriate amount of lift V to
be applied by the vertical drives 112. In the embodiment
illustrated in FIG. 1 , each of the vertical drives 112 may
have a screw jack 114 and therefore the control signal 126
may be an electrical pulse, timed output, change in
frequency , or other type of electrical communication to
raise one of the side dams 106. The amount of lift of
these side dams 106 is controlled so that the side dams
provide the desired spread angle a to encourage consistent
temperature control of the molten metal in the slantwise
groove 110 while avoiding leakage of molten metal from the
pool casting P spread.
FIG. 5B shows the arc-shaped slantwise groove 110
in further detail where the relationship between X , Y ' ,
and a is illustrated relative to the casting rolls 102,
104 and side dams 106. This view is taken along line B-B
in FIG. 5A. As shown, the value Y ' is the radial
displacement of the slantwise groove 110 and is
perpendicular to the lateral displacement X of the side
dam 106.
An examination of the amount of lifting movement
V for a spread angle a from 10-70° was made and is
provided in the following Table 1 . In this arrangement,
the diameter of the casting rolls 102, 104 was each 500 mm
(radius R =250 mm) , the side dams 106 abrasion (X) was 10
mm, and the highest level of lift while preventing leakage
was 15 mm (related to height PL) . As will be appreciated
from the following table , at certain spread angles
(greater than approximately 45°), the amount of lifting
movement V is too high to prevent leakage of molten metal
from the pool P . Therefore, these spread angles a would be
unsuitable given the provided limitations .
Table I :
As shown, when the spread angle a was within the
range of 20-45°, the amount of metal invading and heating
the slantwise grooves was found to be high. Further, when
the spread angle and lifting movement were around the
maximum allowable lift, molten metal flow and heating into
the grooves 110 was as desired. In this example then a
target spread angle a of 45° is desired.
An alternative embodiment of the invention is
illustrated in FIG. 6 . In this embodiment, the slantwise
groove 110 may be comprised of first i and second 0 2
spread angles. According to this embodiment, during a
first part of the casting campaign first spread angle i is
the target angle provided to the control device 122. This
angle is maintained for a first compression distance i . A
second angle 0 2 is then provided during a second segment of
the casting campaign for a second compression distance 2.
According to the embodiment illustrated in FIG. 6 , the
second spread angle 0 2 is smaller than the first spread
angle a i , thereby forming a concave slantwise groove 110.
Alternatively, the second spread angle 0 2 may be larger
than the first spread angle a creating a convex arc-shaped
slantwise groove 110. Further, while the embodiment
illustrated shows first (Xi and second 0 2 spread angles , the
apparatus may be designed to include any number of angles
or regular or irregular steps , or may be a smooth curve ,
such as a part of a part of a circle, parabola, or the
like.
FIG. 7 illustrates another embodiment of the twin
roll caster system 100. In this embodiment, rather than a
compression device 108 providing a lateral force FL and a
vertical drive 112 netting a vertical force Fv , an angled
compression device 128 is provided to directly generate
compression force Fc . This angled compression device 128
may produce an application force F at a predetermined
application angle g . According to the embodiment
illustrated in FIG. 7 , the angled compression device 128
is provided on an adjustable table 130 and an angular
displacement adjustment mechanism 132 , such as a screw
drive or other fine adjustment mechanism may also be
provided on one end of the adjustable table 130 . The other
end of the adjustable table 130 may be secured by a pivot
134 so that the application angle g is adjustable by means
of the angular displacement adjustment mechanism 132 .
As with the embodiment illustrated in FIG. 1 ,
control device 122 may also be provided for determining
the appropriate application angle g to give a desired
spread angle a for the V-shaped groove 110 (see FIG. 4 ) .
The control device 122 may receive as inputs the amount of
displacement X ' of the angled compression device 128,
preferred spread angle a , pool height PL, and roll radius
R and output to the angular displacement adjustment
mechanism 132 a command signal 126 indicating the amount
of displacement necessary to provide the appropriate
application angle.
Yet another embodiment of the twin roll caster
system 100 is illustrated in FIG. 8 . Unlike the embodiment
illustrated in FIG. 7 , the embodiment of FIG. 8 is fixed
at a desired application angle g and is not adjustable.
Further, no control device 122 (FIG. 7 ) is provided for
measuring, monitoring or adjusting the compression angle g
during a casting campaign.
According to the various embodiments described
above, the compression devices 108 or angled compression
devices 128 may be pneumatic, hydraulic, screw-driven, or
other types of pistons having an arm and a body . The
amount of displacement of the compression devices 108 or
angled compression devices 128 may be given by the amount
of displacement of the arm. Alternatively, a separate
displacement measuring device 136 may be provided for
measuring the displacement X of the side dam 106 during
the casting operation. Further, according to one
embodiment the pistons of the compression devices 108 or
angled compression devices 128 may be each secured to the
side dam 106 by means of a jig 138 or similar apparatus.
Alternatively, these compression devices 108 or angled
compression devices 128 may be directly connected to the
side dam 106.
Figs . 9A and 9B show a top view of prior art twin
roll caster system 200 which applies a lateral force FL to
side dams 106 without a lifting or vertical force Fv and
providing a small gap 110 which has no appreciable spread
angle a .
This written description uses examples to
disclose the invention, including the best mode, and also
to enable one of ordinary skill in the art to practice the
invention , including making and using any devices or
systems and performing any incorporated methods . The
patentable scope of the invention is determined by the
claims, and may include other examples that occur to one
of ordinary skill in the art. Such other examples are
intended to be within the scope of the claims if they have
structural elements that do not differ from the literal
language of the claims , or if they include equivalent
structural elements with insubstantial differences from
the literal language of the claims .

CLAIMS :
1 . A twin roll caster comprising:
a pair of counter-rotatable casting rolls having
casting surfaces laterally positioned to form a nip there
between through which thin cast strip can be cast, and
supporting a casting pool of molten metal on the casting
surfaces above the nip;
a pair of side dams positioned to engage end
portions of the casting rolls adjacent the nip to
laterally confine said casting pool; and
a side dam support applying a compression force
against at least one of said side dams at an upward angle
between 15° and 45° relative to an axis of said casting
rolls .
2 . The twin roll caster as set forth in claim 1
where during operation said side dam is worn by said end
surfaces of said casting rolls to form a slantwise groove
in the side dam.
3 . The twin roll caster as set forth in claim 2
where the slantwise groove is in the form of a V-shaped
arcuate groove .
4 . The twin roll caster as set forth in any one of
the preceding claims where said side dam support comprises
a lateral pushing apparatus for pushing said side dam
against said end surfaces and a vertical pushing apparatus
for adjusting the height of said lateral pushing
apparatus , and where the lateral pushing apparatus and the
vertical pushing apparatus are adapted to operate at the
same time .
5 . The twin roll caster as set forth in claim 4
further comprising a control device adapted to control
said vertical pushing device and said lateral pushing
device to provide a target compression angle .
6 . The twin roll caster as set forth in any one of
claims 1 to 3 where said side dam support comprises a
slantwise pushing apparatus for pushing said side dam
against said end surfaces of the casting roll at a target
compression angle.
7 . The twin roll caster as set forth in claim 6
where said compression angle is dynamically controlled.
8 . A twin roll caster comprising:
a pair of counter-rotatable casting rolls having
casting surfaces laterally positioned to form a nip there
between through which thin cast strip can be cast, and
supporting a casting pool of molten metal on the casting
surfaces above the nip;
a pair of side dams positioned to engage end
portions of the casting rolls adjacent the nip to
laterally confine said casting pool; and
a side dam support applying an angular
compression force against each said side dams at an upward
angle between 15° and 45° relative to an axis of said
casting rolls .
9 . The twin roll caster as set forth in claim 8
where during operation each side dam is worn by opposite
end surfaces of said casting rolls to form slantwise
grooves in each side dam.
10. The twin roll caster as set forth in claim 9
where each slantwise groove is in the form of a V-shaped
arcuate groove .
11. The twin roll caster as set forth in any one of
claims 8 to 10 where each said side dam support comprises
a lateral pushing apparatus for pushing said side dam
against said end surfaces and a vertical pushing apparatus
for adjusting the height of said lateral pushing
apparatus , and where the lateral pushing apparatus and the
vertical pushing apparatus are adapted to operate at the
same time .
12. The twin roll caster as set forth in claim 11
further comprising a control device adapted to control
each said vertical pushing device and each said lateral
pushing device to provide a target compression angle.
13 . The twin roll caster as set forth in any one of
claims 8 to 10 where each said side dam support comprises
a slantwise pushing apparatus for pushing said side dam
against end surfaces of the casting roll at a target
compression angle.
14. The twin roll caster as set forth in claim 13
where said compression angle is dynamically controlled.
15 . A method of controlling a twin roll caster having
two laterally positioned casting rolls forming a nip there
between and two side dams positioned adjacent opposite end
portions of the casting rolls to enable a casting pool to
be formed on the casting rolls above the nip. the method
comprising the steps of:
providing a compression device to apply a
compression force against said side dams towards end
portion of said casting rolls at an upward angle, and
applying the compression force against said side
dams and forming slantwise grooves worn in the side dams
by said end portions of said casting rolls .
16. The method of controlling a twin roll caster as
claimed in claim 15 where:
the compression device applies the compression
force to form slantwise grooves in the form of V-shaped
grooves by the steps of:
determining a target step thickness and a spread
angle of said V-shaped grooves; and
controlling the compression device to provide the
compression angle to provide said target step thickness
and spread angle in the side dams .
17. The method as set forth in claim 16 wherein said
compression device provides a lateral force parallel to an
axis of said casting rolls and a vertical force
perpendicular to said lateral force that a resultant force
is equal to said compression force to provide said
compression angle.
18. The method as set forth in claim 17 further
comprising the steps of providing a control device to
determine said compression angle and communicate with said
compression device to adjust said compression angle .
19. The method as set forth in claim 16 where said
compression device includes a slantwise compression device
for providing said compression force at said compression
angle .
20. The method as set forth in claim 19 where said
slantwise compression device includes an angular
adjustment member for adjusting said compression angle .
21. The method as set forth in claim 20 where said
slantwise compression device includes a displacement
measuring device.
22. The method as set forth in claim 21 comprising
the further steps of communicating a displacement value
from said displacement measuring device to the control
device, determining a target compression angle based on
said displacement value and a target spread angle , and
communicating a value to said angular adjustment member to
adjust said slantwise compression device to said target
compression angle.
23 . The method as set forth in claim 22 where said
spread angle is variable .
24. The method as set forth in claim 22 where said
spread angle is fixed.
25. A twin roll caster comprising:
a pair of counter-rotatable casting rolls having
casting surfaces adapted to be laterally positioned to
form a nip there between through which thin cast strip can
be cast and for supporting a casting pool of molten metal
on the casting surfaces above the nip;
a pair of side dams adapted to be positioned to
engage end portions of the casting rolls adjacent the nip
to laterally confine said casting pool; and
a side dam supported for applying a compression
force against at least one of the said side dams at an
upward angle between 15° and 45° relative to an axis of
said casting rolls .
26. A twin roll caster comprising:
a pair of counter-rotatable casting rolls having
casting surfaces adapted to be laterally positioned to
form a nip there between through which thin cast strip can
be cast and for supporting a casting pool of molten metal
on the casting surfaces above the nip;
a pair of side dams adapted to be positioned to
engage end portions of the casting rolls adjacent the nip
to laterally confine said casting pool; and
a side dam support for applying an angular
compression force against each said side dams at an upward
angle between 15° and 45° relative to an axis of said
casting rolls .