[0001] The present invention relates to an apparatus for the continuous casting of metals
in strip form and, more particularly, to a new and improved roll caster providing
substantially isothermal cooling of the casting roll's shell.
[0002] The use of internally chilled rollers in the continuous casting of molten metal in
strip form is well known. U.S. Patent 2,850,776 to Hunter discloses a roller for continuous
casting machines having a plurality of helical coolant channels. Each coolant channel's
helical, single convolution construction allows the coolant flowing in each channel
only one revolution. The patent states that this arrangement permits the equal exposure
of the coolant in all the channels to the shell of the roller and the uniform extraction
of heat from the roller's shell. However, the Hunter patent states that a slight temperature
gradient is present from one end of the roller to the other during the casting process
as well as states that this temperature gradient has no noticeable effect on roller
operation.
[0003] West German Auslegeschrift No. 1,508,927, published December 6, 1973, discloses an
internally cooled roller having a core and a sleeve. Helical coolant channels run
between the core and the sleeve having inlets alternately on one or the other front
face of the roller. The infeed and the run-off channels enter and discharge on the
same facial side of the core of the roller.
[0004] U.S. Patents 3,712,366 and 3,845,810 to Gerding both describe a rotatable drum which
is liquid cooled internally having a spider carrying rollers in radial slots which
roll on the drum's inner surface by centrifugal force. The spider rotates at an appropriate
speed such that the cooling liquid is thrown against the drum's inner surface by centrifugal
force. These patents also state that the action of the rollers on the drum's inner
surface breaks up incipient film boiling.
[0005] U.S. Patent 4,074,750 to Beghin discloses an internally cooled roll having two coaxial
trunnions and a cylindrical body. The internally cooled roll could have a plurality
of cylindrical longitudinal conduits evenly spaced about the axis of the cylindrical
body in an annular arrangement with a tubular conduit located in each longitudinal
conduit, or could have a singular annular longitudinal conduit having either tubular
conduits evenly spaced within the singular annular longitudinal conduit or a single
tube coaxially located within the singular annular longitudinal conduit, or could
have a cylindrical longitudinal conduit with a tubular conduit coaxially located within
the cylindrical longitudinal conduit. Cooling fluid is circulated through the conduits
and the means for supplying the cooling fluid to one of the conduits and removing
the cooling fluid from the other conduit include a fluid collector element in a passage
in one of the trunnions.
[0006] U.S. Patent 3,757,847 to Sofinsky et al. describes a roll mould with a cooling system.
Each roller has a shaft within a sleeve, a central bore, circular passageways and
radial passageways. A header is provided in the central bore to divide the radial
passageways into separate sections; one part for supplying cooling fluid and the other
part for draining cooling fluid. The patent states that uniform heat removal from
the hot metal over the length and height of the crystallization zone is achieved since
coolant of the same temperature and in a constant amount is supplied to the cooling
system.
[0007] U.S. Patent 2,790,216 to Hunter discloses a cooling system in rollers for the continuous
casting of metal. Each roller has a core and a shell over the core. The core's surface
has longitudinal channels whose ends are in communication with annular grooves and
radiating passages intersect the annular grooves. The roller has a central bore, which
is counterbored. Through the counterbore there is extended a conduit forming an inner
passageway communicating with the central bore. Coolant flows through the counterbore
and then proceeds in an outwardly direction through one set of radiating passages
to the longitudinal channels. The coolant flow continues through the longitudinal
channels returning through another set of radiating passages to the central bore,
the conduit extending through the counterbore and a return pipe.
[0008] British Patent Specification 897,412 discloses a cooling system for casting rolls.
Each casting roll has a core and over the core is a sleeve. Within the core are two
longitudinal inlet channels and two longitudinal outlet channels. The longitudinal
inlet and longitudinal outlet channels communicate with the core's periphery by means
of small channels. These small channels open into annular grooves at the core's periphery.
Coolant enters through the longitudinal inlet channels and flows upwardly to the annular
grooves through the connecting smaller channels. The coolant then flows through the
annular grooves and exits the annular grooves through those smaller channels which
connect to the longitudinal outlet channels.
[0009] British Patent Specification 1,319,185 describes an internally cooled roller. Each
casting roller is hollow and is mounted on two hollow shafts. The first hollow shaft
serves as an inlet for the coolant and the second hollow shaft serves to discharge
the coolant. The first hollow shaft communicates with a plurality of pipes radially
disposed in the roller. Each radially disposed pipe communicates with a horizontal
pipe appropriately spaced within the roller. The horizontal pipes have nozzles to
spray the coolant at the roller's inner surface. The coolant is discharged from the
casting roller by the second hollow shaft. The second hollow shaft extends centrally
within the casting roller and has perforations through which the coolant can be discharged.
[0010] The objective of the present invention is to provide a new and improved roll caster
for use in an apparatus for the continuous casting of metal in strip form whereby
substantially isothermal cooling is provided to the casting roll's shell.
[0011] Two important objectives for a cooling system for casting rolls are: first, to reduce
the thermal axial camber on the casting rolls resulting from the molten metal contacting
the casting rolls; and second, to provide substantially uniform heat removal from
the molten metal as it contacts the casting rolls to promote the production of high
quality metal in strip form. Thermal axial camber may cause variations in the casting
gap, that is the gap between a pair of parallel casting rolls in a roll caster, which
may result in unacceptable gauge variations in the cooled and solidified metal. In
the present invention, substantially isothermal cooling is provided to the casting
roll's shell so the casting roll's shell surface temperature will be substantially
constant and little or no thermal axial camber will be present in either the roll
necks or the shell of the casting roll. Thus, thermal axial camber on the casting
roll is greatly reduced, the casting gap remains substantially constant, and substantially
uniform heat removal from the molten metal contacting the casting roll's shell is
provided. Prior art cooling rolls have not as efficiently or effectively met these
objectives since either temperature variations are present around the casting roll's
shell caused by the coolant temperature's rise as the coolant circulates through the
cooling system or thermal axial camber develops in the casting roll's necks or shell
caused by one-half on the casting roll running at a warmer temperature than the other
one-half of the casting roll as the coolant circulates through the cooling system.
In some cases, both temperature variations around the casting roll's shell and thermal
axial camber are present during operation of the cooling system. An important advantage
of the isothermal shell cooling method of the present invention is that the rate of
coolant flow and the degree of temperature rise of the coolant as it circulates through
the cooling system are not considered to be critical.
[0012] According to the invention there is provided a casting roll for use in a roll caster
for continuous casting of metals in strip form, said casting roll comprising a roll
and a shell therearound characterized by at least one axial feed bore for supplying
cooling fluid into the roll and at least one axial drain bore for draining cooling
fluid from the roll, a plurality of parallel annular grooves around the roll for flow
of cooling fluid between the roll and the shell, a plurality of radial feed passageways
connecting each axial feed bore to the annular grooves and a plurality of radial drain
passageways connecting each axial drain bore to the annular grooves with each of said
radial feed and radial drain passageways servicing at least one groove and with the
radial feed passageway connected to the groove on the generally opposite side of the
roll from the radial drain passageway for the same groove and with each radial feed
passageway extending radially outwardly from an axial feed bore in a direction generally
opposite from each immediately adjacent radial feed passageway and with each radial
drain passageway extending radially outwardly from an axial drain bore in a direction
generally opposite from each immediately adjacent radial drain passageway to provide
substantially isothermal cooling of said shell.
[0013] The invention also provides a roll caster for continuous casting of metals in strip
form which comprises a pair of such casting rolls spaced slightly apart to receive
and carry another metal therebetween as it is cooled to solidify the same. Radial
is defined as radiating from the axial feed bore or axial drain bore, respectively,
to the annular grooves.
[0014] In a preferred embodiment of the present invention, each radial feed passageway and
each radial drain passageway services two adjacent annular grooves and each casting
roll has two axial feed bores and two axial drain bores which alternate in servicing
the radial feed passageways and the radial drain passageways along the length of the
roll.
[0015] To assist in understanding the present invention, the attached drawings described
below are illustrative of the preferred embodiment.
Figure 1 is an elevational view of a single casting roll of a roll caster constructed
in accordance with the principles of the invention having a portion of the sleeve
removed.
Figure 2 is a cross-section taken along line 2-2 of Fig. 1.
Figure 3 is a cross-section taken along line 3-3 of Fig. 1.
Figure 4 is a fragmentary top view of a portion of the left portion of Fig. 1 where
the sleeve has been broken away to expose the roll of the roll caster of Fig. 1. Figure
4 is shown proportionately larger than Figs. 1, 2 and 3 for ease of viewing.
Figures 5 and 6 are schematics showing the flow of cooling fluid to, through and from
adjacent pairs of adjacent annular grooves.
[0016] Fig. 1 shows a single casting roll 10 of a roll caster of the present invention in
an elevational view. Preferably, at least one pair of casting rolls would be used
in the practice of the present invention. The casting roll is comprised of a roll
12 having a sleeve 14 over the roll 12. The roll 12 has roll neck portion 16 disposed
at each end thereof. A portion of the sleeve 14 has been removed in Fig. 1 to show
a portion of roll 12. A plurality of parallel annular grooves 18 are provided in the
outer surface of roll 12. Preferably, the parallel annular grooves 18 are evenly spaced
along the length of roll 12; and, preferably, each of the grooves 18 has substantially
the same dimensions.
[0017] Figs. 2 and 3 are cross-sections taken along lines 2-2 and 3-3, respectively, of
Fig. 1. The cross-sections show roll 12 with axial feed bores 20a and 20b and axial
drain bores 22a and 22b preferably generally disposed about and evenly spaced around
the central area of roll 12. The preferred embodiment of a casting roll of the present
invention shown in the drawings has two axial feed bores 20a and 20b and two axial
drain bores 22a and 22b. However, a casting roll may have one or more axial feed bores
and one or more axial drain bores in other embodiments of the present invention, if
appropriate. Also, it is preferred that the number of axial feed bores equal the number
of axial drain bores in a casting roll of the present invention; and it is preferred
that each of both the axial feed bores and the axial drain bores has substantially
similar dimensions for length and for diameter.
[0018] Radial feed passageways 24a and 24b and radial drain passageways 26a and 26b are
shown in Figs. 2 and 3. It is preferred that each of both the radial feed passageways
and the radial drain passageways has substantially similar dimensions for length and
for diameter. In the preferred embodiment of the invention, each radial feed passageway
connects two adjacent annular grooves to an axial feed bore; and each radial drain
passageway connects two adjacent annular grooves to an axial drain bore. Radial feed
passageway 24a and radial drain passageway 26a shown in Fig. 2 service adjacent annular
grooves 18a and 18b shown in Fig. 1; and radial feed passageway 24b. and radial drain
passageway 26b shown in Fig. 3 service adjacent annular grooves 18c and 18d of Fig.
1. While in the preferred embodiment of the invention each radial feed passageway
and each radial drain passageway service two adjacent annular grooves, each of said
radial feed and radial drain passageways could service only one annular groove or
could service three or more adjacent annular grooves in other embodiments of the invention,
if appropriate.
[0019] As illustrated in Figs. 2 and 3, the axial feed bores 20a and 20b alternate in servicing
the radial feed passageways; and the axial drain bores 22a and 22b alternate in servicing
the radial drain passageways. In this preferred embodiment of the present invention,
the alternating pattern for the axial feed bores and the axial drain bores to service
the radial feed passageways and the radial drain passageways, respectively, would
continue along the length of roll 12. In another embodiment of the invention, now
shown in the drawings, if, for example, only a single axial feed bore and only a single
axial drain bore are utilized to service the radial feed passageways and the radial
drain passageways, respectively, an alternating pattern for servicing the radial feed
passageways and the radial drain passageways clearly would not be present. However,
in other embodiments of the invention, if more than two axial feed bores are utilized
to service the radial feed passageways, preferably the axial feed bores would alternate
in servicing the radial feed passageways along the length of the roll, or if more
than two axial drain bores are utilized to service the radial drain passageways, preferably
the axial drain bores would alternate in servicing the radial drain passageways along
the length of the roll.
[0020] In Fig. 2, the bottom surface of annular groove 18b is indicated by dotted line 28;
and annular groove 18b is not visible in this cross-section except in the general
areas of the intersections of radial feed passageway 24a and radial drain passageway
26a with annular groove 18b. Likewise, in Fig. 3 the bottom surface of annular groove
18d is indicated by dotted line 30; and annular groove 18d is not visible in this
cross-section except in the general areas of the intersections of radial feed passageway
24b and radial drain passageway 26d with annular groove 18d. The arrows in Figs. 2
and 3 indicate the direction of flow of the cooling fluid.
[0021] Fig. 4 is a refractory top view of a portion of roll 12 of Fig. 1 showing radial
feed passageway 24a servicing adjacent annular grooves 18a and 18b and radial drain
passageway 26b servicing adjacent annular grooves 18c and 18d. The arrows in Fig.
4 indicate the direction of flow of the cooling fluid.
[0022] Considering Figs. 2, 3 and 4, it can be seen that the radial feed passageway connects
to two adjacent annular grooves on the generally opposite side of roll 12 from the
radial drain passageway for the same two adjacent annular grooves. In other embodiments
of the invention, regardless of whether a radial feed passageway and a radial drain
passageway service a singular annular groove or two or more adjacent annular grooves,
the radial feed passageway connects to the annular groove or adjacent annular grooves
on the generally opposite side of the roll from the radial drain passageway for the
same annular groove or adjacent annular grooves.
[0023] Also, as can be seen from Figs. 2 and 3, radial feed passageway 24a is generally
disposed on the opposite side of roll 12 from adjacent radial feed passageway 24b;
and radial drain passageway 26a is generally disposed on the opposite side of roll
12 from adjacent radial drain passageway 26b. Along the entire length of the roll,
each radial feed passageway extends radially outwardly from an axial feed bore in
a direction generally opposite from each immediately adjacent radial feed passageway
and each radial drain passageway extends radially outwardly from an axial drain bore
in a direction generally opposite from each immediately adjacent radial drain passageway
in the preferred embodiment or in any other embodiment of the present invention to
provide the desired isothermal cooling.
[0024] Figs. 5 and 6 schematically show preferred flow patterns for cooling fluid through
adjacent annular grooves 18a and 18b and through adjacent annular grooves 18c and
18d. Fig. 5 shows the flow of cooling fluid from axial feed bore 20a through radial
feed passageway 24a, adjacent annular grooves 18a and 18b and radial drain passageway
26a into axial drain bore 22a. Fig. 6 shows the flow of cooling fluid from axial feed
bore 20b through radial feed passageway 24b, adjacent annular grooves 18c and 18d,
and radial drain passageway 26b into axial drain bore 22b. The arrows indicate the
direction of flow of the cooling fluid.
[0025] From Figs. 5 and 6 it can be seen that the flow of cooling fluid through annular
grooves 18a and 18b is opposite to the flow of cooling fluid through annular grooves
18c and 18d. The flow of cooling fluid through annular grooves 18a, b, c and d shows
the alternating, opposing flow pattern for the cooling fluid present in a casting
roll of the present invention. In the preferred embodiment of the present invention,
the flow pattern commences in these two adjacent pairs of adjacent annular grooves
and continues throughout the entire length of the roll. Therefore, in the preferred
embodiment of a casting roll of the present invention, the flow of cooling fluid through
each pair of adjacent annular grooves serviced by the same radial feed passageway
and by the same radial drain passageway would be opposite to the flow of the cooling
fluid through an adjacent pair of adjacent annular grooves serviced by an adjacent
radial feed passageway and by an adjacent radial drain passageway. This alternating,
opposing flow pattern is achieved by alternating the placement of the radial feed
passageways from generally one side of the roll to the other along the length of the
roll such that each radial feed passageway extends radially outwardly from an axial
feed bore in a direction generally opposite from each immediately adjacent radial
feed passageway and by alternating the placement of the radial drain passageways generally
from one side of the roll to the other along the length of the roll such that each
radial drain passageway extends radially outwardly from an axial drain bore in a direction
generally opposite from each immediately adjacent radial drain passageway, as well
as by having the radial feed passageway servicing two adjacent annular grooves connect
on the generally opposite side of the roll from the radial drain passageway servicing
the same annular grooves.
[0026] With regard to other embodiments of the invention, since a single radial feed passageway
and a single radial drain passageway could possibly service a single annular groove
or two or more adjacent annular grooves, it would by apparent to those skilled in
the art that in a casting roll constructed in accordance with the principles of this
invention, an alternating, opposing flow pattern for the cooling fluid would be present
in the annular grooves along the entire length of the roll in other embodiments of
the invention. Since, in other embodiments of the present invention, the flow of cooling
fluid through the annular groove or grooves, as the case may be, serviced by the same
radial feed passageway and by the same radial drain passageway would be opposite to
the flow of cooling fluid through the adjacent annular groove or grooves, as the case
may be, serviced by an adjacent radial feed passageway and by an adjacent radial drain
passageway.
[0027] This alternating, opposing flow pattern promotes the isothermal cooling of the casting
roll's shell by providing a means for substantially uniform heat removal from the
shell of the casting roll. The alternating placement of the radial feed passageways
and the radial drain passageways along the length of the roll, as previously described,
allows relatively cool coolant entering the annular grooves or groove, as the case
may be, to then circulate next to and opposite to relatively warmer coolant circulating
through the adjacent annular grooves or groove, as the case may be, to substantially
uniformly balance along the casting roll's shell the heat being transferred from the
molten metal. By balancing the heat transfer in this manner, the temperature of the
casting roll's shell will be substantially uniform both around the shell's circumference
and across the roll's width.
[0028] The balancing of the heat transferred through the casting roll is also enhanced by
the placement in the casting roll in accordance with the invention of the radial feed
passageways carrying the relatively cool entering coolant and the radial drain passageways
carrying the warmer exiting coolant. By having a radial feed passageway carrying the
cool entering coolant servicing the annular groove or grooves, as the case may be,
on the generally opposite side of the roll from a radial drain passageway carrying
the warmer exiting coolant from the same annular groove or grooves and by having the
radial feed passageways alternate with the radial drain passageways along both sides
of the roll along the length of the roll, it can be seen that the cooler entering
coolant flowing in the radial feed passageways substantially balances throughout the
casting roll the heat flow from the warmer exiting coolant flowing in the radial drain
passageways to promote substantially uniform heat distribution throughout the casting
roll.
[0029] In the preferred embodiment of the invention, the balancing of the heat transferred
through the casting roll is further enhanced by the use of two axial feed bores and
two axial drain bores which alternate in servicing the radial feed passageways and
the radial drain passageways, respectively, along the length of the roll. By arranging
the two axial feed bores and the two axial drain bores in the casting roll as shown
in Figs. 2 and 3 such that the axial feed bores and the axial drain bores are generally
disposed about and evenly spaced around the central area of the casting roll with
the axial feed bores being generally disposed diagonally opposite from each other
and the axial drain bores being generally disposed diagonally opposite from each other,
the cooler entering coolant flowing in the axial feed bores helps to substantially
balance the heat flow from the warmer exiting coolant flowing in the axial drain bores
thereby assisting with the substantially uniform distribution of heat through the
casting roll.
[0030] Thus, the present invention's capability to substantially uniformly balance and distribute
the heat being transferred from the molten metal throughout the casting roll provides
substantially isothermal cooling of the casting roll's shell.
1. A casting roll for use in a roll caster for continuous casting of metals in strip
form, said casting roll comprising a roll and a shell therearound characterized by
at least one axial feed bore for supplying cooling fluid into the roll and at least
one axial drain bore for draining cooling fluid from the roll, a plurality of parallel
annular grooves around the roll for flow of cooling fluid between the roll and the
shell, a plurality of radial feed passageways connecting each axial feed bore to the
annular grooves and a plurality of radial drain passageways connecting each axial
drain bore to the annular grooves with each of said radial feed and radial drain passageways
servicing at least one groove and with the radial feed passageway connected to the
groove on the generally opposite side of the roll from the radial drain passageway
for the same groove and with each radial feed passageway extending radially outwardly
from an axial feed bore in a direction generally opposite from each immediately adjacent
radial feed passageway and with each radial drain passageway extending radially outwardly
from an axial drain bore in a direction generally opposite from each immediately adjacent
radial drain passageway to provide substantially isothermal cooling of said shell.
2. A casting roll according to claim 1, characterized by the fact that the roll has
two axial feed bores which alternate in servicing the radial feed passageways and
two axial drain bores which alternate in servicing the radial drain passageways along
the length of the roll.
3. A casting roll according to claim 2, characterized by the fact that the two axial
feed bores and the two axial drain bores are generally disposed about and evenly spaced
around the central area of the roll with the axial feed bores being generally disposed
diagonally opposite from each other and with the axial drain bores being generally
disposed diagonally opposite from each other.
4. A casting roll according to any one of the preceding claims, characterized by the
fact that each radial feed passageway and each radial drain passageway services two
adjacent annular grooves.
5. A roll caster for continuous casting of metals in strip form comprising a pair
of parallel casting rolls according to any one of the preceding claims spaced apart
slightly to receive and carry molten metal therebetween as it is cooled to solidify
the same.