U.S. patent application number 10/304276 was filed with the patent office on 2004-05-27 for heated controlled deflection roll.
Invention is credited to Gerndt, Robert James, Lau, Jark C., Sayovitz, John Joseph.
Application Number | 20040102298 10/304276 |
Document ID | / |
Family ID | 32325172 |
Filed Date | 2004-05-27 |
United States Patent
Application |
20040102298 |
Kind Code |
A1 |
Gerndt, Robert James ; et
al. |
May 27, 2004 |
Heated controlled deflection roll
Abstract
A heated controlled deflection roll including a center support
and a rotatable roll shell surrounding the center support. A shoe
assembly connects the center support and the inside surface of the
rotatable roll shell. The shoe assembly includes a shoe in contact
with the inside surface of the rotatable roll shell and a bladder
positioned between the shoe and the center support. The shoe
assembly has a length substantially equal to a length of the inside
surface of the rotatable roll shell. Free space within a chamber
within the rotatable roll shell is filled with a heat transfer
fluid and heater elements. The heater elements have angled fins for
directing the flow of the heat transfer fluid in a helical pattern
towards one end of the rotatable roll shell. The heat transfer
fluid returns to the opposite end of the chamber through a passage
through the center support.
Inventors: |
Gerndt, Robert James;
(Roswell, GA) ; Lau, Jark C.; (Roswell, GA)
; Sayovitz, John Joseph; (Marietta, GA) |
Correspondence
Address: |
PAULEY PETERSEN KINNE & ERICKSON
2800 WEST HIGGINS ROAD
SUITE 365
HOFFMAN ESTATES
IL
60195
US
|
Family ID: |
32325172 |
Appl. No.: |
10/304276 |
Filed: |
November 26, 2002 |
Current U.S.
Class: |
492/6 |
Current CPC
Class: |
D21F 5/027 20130101;
F16C 13/026 20130101; D21G 1/022 20130101; D21G 1/0266
20130101 |
Class at
Publication: |
492/006 |
International
Class: |
D21G 001/02 |
Claims
What is claimed is:
1. A controlled deflection roll, comprising: a center support; a
rotatable roll shell including an inside surface surrounding the
center support; and a shoe assembly including a shoe in contact
with the inside surface of the rotatable roll shell and a bladder
positioned between the shoe and the center support, the shoe
assembly having a length substantially equal to a length of the
inside surface of the rotatable roll shell.
2. The controlled deflection roll of claim 1, wherein the bladder
contains one of a gas and a fluid.
3. The controlled deflection roll of claim 2, wherein the bladder
exerts a load on the shoe when a pressure within the bladder is
increased.
4. The controlled deflection roll of claim 1, further comprising an
end element surrounding the center support on each end of the roll
shell, the rotatable roll shell and the end elements enclosing a
chamber containing a heat transfer fluid.
5. The controlled deflection roll of claim 4, wherein the heat
transfer fluid flows within the chamber around the center support
in a direction of rotation of the rotatable shell.
6. The controlled deflection roll of claim 5, further comprising a
shoe assembly bypass in combination with the shoe assembly.
7. The controlled deflection roll of claim 6, wherein the shoe
assembly bypass allows the heat transfer fluid to flow between the
bladder and the center support.
8. The controlled deflection roll of claim 4, further comprising at
least one heater element within the chamber and in contact with the
heat transfer fluid.
9. A controlled deflection roll, comprising: a center support; a
shoe assembly in combination with the center support; a rotatable
roll shell including an inside surface contacting the shoe
assembly, the rotatable roll shell surrounding the center support;
an end element surrounding the center support on each end of the
roll shell, the rotatable roll shell and the end elements enclosing
a chamber; and a heat transfer fluid within the chamber, wherein
the heat transfer fluid flows within the chamber around the center
support in a direction of rotation of the rotatable shell.
10. The controlled deflection roll of claim 9, further comprising a
heat transfer fluid expansion line connecting the chamber to a heat
transfer fluid expansion tank external of the chamber.
11. The controlled deflection roll of claim 9, further comprising
at least one heater element within the chamber and in contact with
the heat transfer fluid.
12. The controlled deflection roll of claim 11, further comprising
fins on at least one of the heater element and the center
support.
13. The controlled deflection roll of claim 12, wherein the fins
are configured to direct the flow of the heat transfer fluid in a
helical pattern around the center support from one end of the
chamber to an opposite end of the chamber.
14. The controlled deflection roll of claim 13, further comprising
a heat transfer fluid passage extending through a length of the
center support.
15. The controlled deflection roll of claim 9, wherein the shoe
assembly has a length substantially equal to a length of the
rotatable roll shell.
16. The controlled deflection roll of claim 15, further comprising
a shoe assembly bypass in combination with the shoe assembly.
17. A controlled deflection roll, comprising: a center support; a
rotatable roll shell including an inside surface surrounding the
center support; an end element surrounding the center support on
each end of the roll shell, the rotatable roll shell and the end
elements enclosing a chamber; at least one heater element within
the chamber; a heat transfer fluid within the chamber; and at least
one angled fin on at least one of the center support and the at
least one heater element for directing a flow of the heat transfer
fluid within the chamber.
18. The controlled deflection roll of claim 17, further comprising
a heat transfer fluid passage extending through a length of the
center support.
19. The controlled deflection roll of claim 17, further comprising
a shoe assembly between the center support and the roll shell.
20. The controlled deflection roll of claim 19, further comprising
a shoe assembly bypass in combination with the shoe assembly.
21. The controlled deflection roll of claim 17, wherein the at
least on angle fin is configured to cause turbulence in the heat
transfer fluid flow as the heat transfer fluid flows over the
surface of the heater element.
22. The controlled deflection roll of claim 17, wherein the heat
transfer fluid fills an annulus of the chamber.
23. The controlled deflection roll of claim 17, wherein the heat
transfer fluid is an oil.
Description
FIELD OF INVENTION
[0001] The present invention relates to a heated controlled
deflection roll useful in pairs or in combination with other types
of rolls for nip rolling fibrous materials such as nonwoven
webs.
BACKGROUND OF THE INVENTION
[0002] Pairs of mated rolls forming a nip through which a traveling
web passes are well known in the field of paper making, and more
recently, in the textile and nonwovens industries to remove water
from the web, calender, bind, or emboss the fibrous web. In such
cases the nip pressures cause the rolls to deflect to an extent
that some form of compensation for the roll deflection must be
provided. Without compensation the resulting nip pressure will be
extremely non-uniform across the width of the rolls.
[0003] One common way of compensating for roll deflection is to
grind a "crown" on one of the mated rolls. Crowning is a common
method of deflection compensation due to its relatively lower cost.
A "crown" is defined as a slight and gradual increase in the
diameter of the roll shell near the center of the roller as
compared to either end. However, the shape of the roll crown is
difficult to identify because the crown must precisely match the
shape of the deflection curve if a uniform nip is to result. Even
when the shape is identified by several iterations of grinding and
observing the resulting nip pressure profile, the precision
required in the grinding process is also difficult to consistently
attain.
[0004] Another disadvantage of roll deflection compensation by
crowning is that, once crowned, the roll is capable of providing a
uniform nip pressure only at the particular value of nip pressure
for which it was planned and calculated. A lower nip pressure will
result in too much pressure at the center, and a higher nip
pressure will result in a much higher pressure at the roll ends.
Being limited to one pressure after grinding a roll to a particular
amount of crown is a disadvantage for most of the processes using
nip rolls.
[0005] Another method of compensating for roll deflection is roll
bending. Roll bending is commonly used in the textile and plastics
industries where highly uniform nip pressures are not required. A
bending moment is placed on the roll ends by two sets of bearings
and extended roll journals. However, the resulting shape of the
rolls typically does not fit the deflection curves exactly.
[0006] Still another method used in the textile industry is to use
rolls of sufficiently large diameter and then cover one or both
rolls with an elastomeric material. The large roll diameters and
flexible covers mitigate the inherent non-uniformity of the nip
pressure. This method is generally limited to processes that allow
the use of a flexible cover, where exact pressure uniformity is not
required, and when a heated nip is not required.
[0007] Self-loading controlled deflection rolls use internal
pistons or "shoes" to move the roll shell into the mated roll. The
stationary pistons or shoes at the nip centerline press on the
rotating roll shell and counterbalance the nip pressure, thereby
forcing the control deflection roll shell into the mated roll shell
as needed to compensate for deflection of the mated rolls.
Controlled deflection rolls are generally more complex than
previously discussed rolls and thus have a higher cost. A commonly
used controlled deflection roll is commonly referred to as a "swim
roll." This type of roll uses a pressure of about two or three bars
in the upper half of an annulus formed by the rotating shell and
the non-rotating center support. Axial seals at the 3:00 and 9:00
o'clock positions run the length of the roll shell/center support.
Circumferential seals on each end are also employed. This design is
generally commercially limited to a 505 millimeter (19.9 inch)
maximum diameter, which limits its use for high speed bonding of
melt spun fibers which typically require larger roll diameters to
increase the bonding time within the nip. Another disadvantage of
this design when used as a heated roll is the maintenance, safety,
and housekeeping concerns associated with pumping hot oil at high
pressures.
[0008] The pistons used in current controlled deflection rolls are
typically loaded with hydraulic pressure supplied by pumps external
to the roll. The oil is brought to cavities at the top of the
pistons. The cavities are formed on one side by the rotating shell.
The cavities are designed to balance the piston force, such that
the pistons float on a hydrostatic cushion of oil. Some oil also
flows out of the cavity lubricating the piston surface in contact
with the rotating shell. Stationary crescent shaped "shoes"
generally use internally generated hydrodynamic oil pressure to
lubricate the shoe/shell interface and prevent metal to metal
contact. Hydrodynamic oil pressure is created when one moving plate
(the roll shell) and one stationary plate (the shoe) are at a
slight angel to each other, creating a wedge as the oil is drawn
into the diminishing clearance between the two plates by the moving
plate. Pressures in excess of 1000 pounds per square inch can be
generated by this method.
[0009] Current controlled deflection rolls are typically limited to
smaller diameters as well as low operating temperatures.
Additionally, controlled deflection rolls are typically expensive
due to the complexity of the loading mechanisms. The cost of
typical current controlled deflection rolls prohibits the use of
the rolls in pairs, which is generally most desirable. Using
controlled deflection rolls in pairs is ideal for nip uniformity
since both roll shells can remain straight, with zero bending
stress (and strain), and zero shear stress (and strain) and
therefore neither roll has to conform to the other.
[0010] Current commercial heated controlled deflection rolls
include external oil heaters and pumps, as well as the piping that
is used to connect these external parts. The high pressure, high
temperature pumps and filters are difficult to maintain and
typically have some oil leakage. Roll changes are difficult because
disconnecting the roll from the external piping causes some loss of
oil. The loss of oil from pump seals, roll changes, and other
maintenance operations are a housekeeping and safety concern.
[0011] There is a need for a less complex, less expensive, large
diameter, heated, controlled deflection roll. There is particularly
a need for low cost controlled deflection rolls that allow for cost
efficient use in pairs. There is a need for a self-contained
controlled deflection roll that does not require many or any
external pumps or heaters, and therefore can more easily be added
or removed from a machine frame.
SUMMARY OF THE INVENTION
[0012] A general object of the invention is to provide improved
heated controlled deflection rolls. A more specific objective of
the invention is to overcome one or more of the problems described
above.
[0013] A general object of the invention can be attained, at least
in part, through a fluid-filled controlled deflection roll
including internal heating elements. The heated controlled
deflection rolls of this invention utilize a hydrodynamic shoe
assembly that extends substantially the full length of an inside
surface of the roll shell.
[0014] In one embodiment of this invention, a controlled deflection
roll includes a center support and a rotatable roll shell including
an inside surface surrounding the center support. A shoe assembly
is between the center support and the inside surface of the
rotatable roll shell. The shoe assembly includes a shoe in contact
with the inside surface of the rotatable roll shell and a bladder
positioned between the shoe and the center support. The shoe
assembly has a length substantially equal to a length of the inside
surface of the rotatable roll shell, and includes a single shoe and
a single bladder that both extend a length substantially equal to a
length of the inside surface of the rotatable roll shell.
[0015] In another embodiment of this invention, the controlled
deflection roll includes a center support, a shoe assembly in
combination with the center support, and a rotatable roll shell,
surrounding the center support and having an inside surface
contacting the shoe assembly. An end element surrounds the center
support on each end of the rotatable roll shell, and the rotatable
roll shell and the end elements enclose a chamber. A heat transfer
fluid is contained within the chamber. The heat transfer fluid is
driven by the inside surface of the rotatable roll shell and flows
within the chamber around the center support in a direction of
rotation of the rotatable shell.
[0016] In yet another embodiment of this invention, a controlled
deflection roll includes a center support, a rotatable roll shell
including an inside surface surrounding the center support, and an
end element surrounding the center support on each end of the roll
shell. The rotatable roll shell and the end elements enclose a
chamber. The center support extends through the chamber and out
past each of the end elements. The chamber encloses at least one
heater element and a heat transfer fluid. At least one of the
center support and the at least one heater element includes at
least one angled fin thereon for mixing and directing the flow of
the heat transfer fluid within the chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] These and other objects and features of this invention will
be better understood from the following detailed description taken
in conjunction with the drawings, wherein:
[0018] FIG. 1 shows a cross section view of a controlled deflection
roll according to an embodiment of this invention.
[0019] FIG. 2 shows a partial sectional view of a controlled
deflection roll according to an embodiment of this invention.
[0020] FIG. 3 shows a partial sectional view of a controlled
deflection roll and frame according to an embodiment of this
invention.
[0021] FIG. 4 shows a partial sectional view of a shoe and a
rotatable roll shell of a controlled deflection roll according to
an embodiment of this invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0022] FIG. 1 shows a cross-sectional view of a controlled
deflection roll 10 of one embodiment of this invention. The
controlled deflection roll 10 of this invention can be used in
combination with a second roll to create a nip between the pair of
rolls through which a fibrous web material, such as a nonwoven
fabric, is run. The controlled deflection rolls of this invention
can be used in combination with various types of rolls known in the
art, such as plain cylindrical heated rolls or other types of
controlled deflection rolls, and is desirably used in combination
with a second, similar controlled deflection roll of this
invention.
[0023] The controlled deflection roll 10 includes a center support
12 extending through the controlled deflection roll 10. A rotatable
roll shell 14 is positioned around the center support 12, such that
an inside surface 16 of the rotatable roll shell 14 surrounds the
center support 12. The inside surface 16 extends between two end
elements 15, one on each side of rotatable roll shell 14. The
center support 12 desirably extends beyond the opposite end
elements 15 of the rotatable roll shell 14 for connecting the
controlled deflection roll 10 to a machine frame, such as supports
50 as shown in FIG. 3. The center support 12 is stationary and
fixed to the machine frame, and will support the controlled
deflection roll 10 within the desired ranges of deflection. The
center support 12 is desirably made of materials such as steel or
cast iron.
[0024] The rotatable roll shell 14 can vary in diameter, and is
suitably about 400 to 2000 millimeters, and desirably about 600 to
1000 millimeters. The rotatable roll shell 14 can be made of
materials such as alloy steel or cast iron. The nip created by the
rotatable roll shell and a second roll shell can be used for
calendering, bonding, or embossing a fibrous material traveling
through the nip. An external surface 17 of the rotatable roll shell
14 can be smooth, rough, or include a pattern for embossing fibrous
webs.
[0025] FIG. 1 shows a shoe assembly 20 including a shoe 22 in
contact with the inside surface 16 of the rotatable roll shell 14
and a bladder 24 positioned between the shoe 22 and the center
support 12. The shoe assembly 20, including both the shoe and the
bladder, has a length substantially equal to a length of the nip
load, which desirably runs about 8 to 20 inches less than the
length of the inside surface 16 of the rotatable roll shell 14. In
one embodiment of this invention, the shoe assembly 20 has a length
substantially equal to a length of the inside surface 16 of the
rotatable roll shell 14, and includes a single shoe 22 and a single
bladder 24 that both extend a length substantially equal to a
length of the inside surface 16 of the rotatable roll shell 14. The
shoe can be made from materials such as brass, bronze, cast iron,
or steel, and is desirably made from brass or bronze in order to
provide a wearing surface against the rotatable shell. As shown in
FIGS. 2 and 3, the rotatable roll shell 14 of this invention has an
end element 15 on each of opposite ends of the rotatable roll shell
14 enclosing a chamber 26 around a length of the center support 12.
The length of the shoe assembly 20 desirably runs approximately the
length of the nip load between the two end elements 15. The end
elements 15 can include various designs and parts; however each of
the end elements 15 typically includes at least one movable part,
such as a roller bearing, that allows the rotatable roll shell 14
to rotate around the center support 12, and seals which seal the
enclosed chamber 26 for containing a heat transfer fluid. As the
end elements 15 include moving parts allowing the rotatable roll
shell 14 to rotate, it is desirable that the ends of the
non-rotating shoe assembly 20 do not contact the end elements 15.
Therefore, the shoe assembly 20 and the end elements 15 are
desirably separated by a minimal space.
[0026] The shoe assembly 20 is connected to the center support 12
via the bladder 24 and is guided and restrained by roller elements
11 on either side of the shoe 22 and fastened to the center support
12. The shoe 22 contacts the inner surface of the rotatable roll
shell 14 and is ground to a diameter slightly less than that of the
inside surface 16. The shoe assembly 20 exerts a load on the
rotatable roll shell 14 in a direction towards a nip between the
controlled deflection roll 10 and a mated second roll. The bladder
24 is made of an expandable elastomeric material such as
VITON.RTM., a fluroelastomer available from DuPont Dow Elastomers,
LLC, or silicone, which allows the bladder 24 to expand when a
pressure within the bladder is increased, and which allows the
bladder 24, and therefore controlled deflection roll 10, to be used
in high temperature applications. The bladder 24 exerts an
increased load on the shoe 22 when the pressure within the bladder
is increased. Oppositely, the load on the shoe 22 can be decreased
by decreasing the pressure within the bladder 24. The controlled
deflection roll 10 of this invention can be used to provide nip
loading up to about 3500 pounds per linear inch and desirably
between about 200 to 1500 pounds per linear inch. The bladder 24
contains one of a gas or fluid such as oil. Desirably the bladder
is pressurized with the same heat transfer fluid used to fill the
chamber 26 between the rotatable shell 14 and the center support
12. The pressure within the bladder 24 is controlled by a
compressed air regulator 27 which feeds air directly to the
bladder, or desirably, as shown in FIG. 3, to an "air over oil"
device 25, such as known in the art, external to the roll which
contains the same heat transfer fluid used inside the chamber 26,
such that the air pressure above the heat transfer fluid maintains
its pressure and allows the fluid to flow in or out of the bladder
24 as needed to maintain the desired pressure.
[0027] The bladder 24 exerts a load on shoe 22 which in turn exerts
a load on the rotatable roll shell 14. As shown in FIG. 4, the shoe
22 desirably includes a circular portion oriented towards the
inside surface 16 of the rotatable roll shell 14. The radius of a
curvature of the shoe 22 must be manufactured to a radius slightly
less than the diameter of the inside surface 16 of the rotatable
roll shell 14. In order to create a desired high hydrodynamic oil
pressure, and thus a safe operating condition for the lubrication
of the shoe, the difference in radii will result in a desirable
average gap at the sides 38 of the shoe 22 which is 2.2 times the
gap at the center 40 of the shoe 22. However, the gap at the center
40 of the shoe 22 is a function of: 1) the load of the shoe; 2) the
viscosity of the heat transfer fluid; and 3) the surface speed of
the inside surface 16 of the rotatable roll shell 14. Therefore,
obtaining the desired gap ratio of 2.2 can be maintained only for
one set of conditions.
[0028] As discussed above, the controlled deflection roll 10
includes an end element 15 at each end of the rotatable roll shell
14. As shown in FIGS. 2 and 3, the end elements 15 surround the
center support at each end of the rotatable roll shell 14 and
include movable parts, such as roller bearings 48. The roller
bearings 48 allow the rotatable roll shell 14 to rotate around the
center support 12. The rotatable roll shell 14 and the end elements
15 enclose a chamber 26 surrounding a portion of the center support
12 between the end elements 15. The chamber 26 includes an annulus
that contains, and is desirably filled with, a heat transfer fluid
28. "Annulus" refers to an interstitial free space within the
chamber 26 around the components of the controlled deflection roll
10 within the chamber 26. The size and dimensions of the annulus
depends on the size and shape of the components of the controlled
deflection roll 10 within the chamber 26, such as the shoe assembly
20 and the center support 12. The heat transfer fluid 28 freely
flows within the annulus of the chamber 26. Upon rotation of the
rotatable roll shell 14, the heat transfer fluid 28 will flow
around the center support 12, as well as around the other
components in the chamber 26, in a direction of rotation of the
rotatable roll shell 14. The heat transfer fluid 28 provides
lubrication between the shoe 22 and the inside surface 16 and can
be used to transfer heat to the rotatable roll shell 14 from one or
more heater elements 30 within the chamber 26. The heat transfer
fluid 28 of this invention includes, without limitation, oils,
synthetic oils or heat transfer fluids. Desirably, the bladder 24
contains the same material as the heat transfer fluid 28 so that if
a small leak occurs in the bladder 24, the leak will not displace
the heat transfer fluid 28 with a different material such as
air.
[0029] In one embodiment of this invention, the controlled
deflection roll 10 includes a shoe assembly bypass 32 in
combination with the shoe assembly 20. The heat transfer fluid 28
flows in a direction of rotation of the rotatable roll shell 14 and
lubricates the surface of shoe 22 exerting force on the inside
surface 16 of the rotatable roll shell 14. The amount of heat
transfer fluid 28 that passes between the shoe 22 and the inside
surface 16 is minimal compared to the total amount of heat transfer
fluid 28 which is desirably flowing circumferentially, and thus the
shoe assembly bypass 32 allows the flow of heat transfer fluid 28
to continue through the chamber 26 and around the center support
12. Thus the shoe assembly bypass 32 prevents an obstruction of the
flow of the heat transfer fluid 28 caused by the shoe 22 and the
shoe assembly 20. The shoe assembly bypass 32 is shown in FIGS. 1
and 3 between the bladder 24 and the center support 12. The shoe
assembly bypass 32 allows the heat transfer fluid 28 to flow
between the bladder 24 and the center support 12. The shoe assembly
bypass 32 can include channels between the connections connecting
the bladder 24 and the center support 12 or be channels formed in
the center support 12. One skilled in the art will appreciate the
various configurations possible for the shoe assembly bypass 32,
such as channels between the bladder 24 and the shoe 22, preformed
passageways through the bladder itself, and combinations of these
embodiments.
[0030] The controlled deflection roll 10 includes at least one
heater element 30 within the chamber and in contact with the heat
transfer fluid 28. FIG. 1 shows two heater elements 30 located
between the center support 12 and the rotatable roll shell 14. As
will be appreciated by one skilled in the art, the heater elements
30 can include various configurations. In one embodiment of this
invention, the heater elements 30 desirably run the length of the
center support 12 within chamber 26. The heater elements 30 are
suitably electric heater elements and made from a conductive
material such as aluminum. The heater elements 30 are shown in FIG.
1 as crescent shaped to fit between the center support 12 and
rotatable roll shell 14. The size and shape of the heater elements
can vary depending on the size and shape of the center support 12
and/or the rotatable roll shell 14.
[0031] The heat transfer fluid 28 passes over the heater elements
30 as it circumferentially flows through the chamber 26 around the
center support 12. The heat produced by the heater elements 30
heats the heat transfer fluid 28 and the heat transfer fluid 28 in
turn heats the rotatable roll shell 14. Suitably the heater
elements 30 and the heat transfer fluid 28 heat an outer surface of
the rotatable roll shell 14 to obtain a temperature of at least
about 100.degree. C., more desirably about 100.degree. C. to
260.degree. C. The controlled deflection roll 10 of this invention
can include an external heat transfer fluid expansion tank 38
connected to the chamber 26 by a heat transfer fluid expansion line
39. The expansion tank holds additional heat transfer fluid 28. If
the heat transfer fluid 28 expands upon heating, an amount of the
heat transfer fluid 28 enters the expansion tank 38 through the
expansion line 39 thereby maintaining a desired low pressure of the
heat transfer fluid 28 within the chamber 26. The expansion tank
can be located above the controlled deflection roll or include an
air cushion (not shown) to balance the pressure of the heat
transfer fluid 28 in the expansion tank with the pressure in the
chamber 26. As shown in FIG. 3, the expansion line 39 can enter the
center support 12 at one end and connect to chamber 26. In one
embodiment the heat expansion tank 38 is located within chamber 26.
In one embodiment of this invention,, the heat expansion tank 38
and the pump 25 for the bladder 24 are both within the chamber 26,
providing a self-contained controlled deflection roll 10. The
self-contained controlled deflection roll 10 allows for easy
removal and roll changes.
[0032] As shown in FIG. 3, the rotatable roll shell 14 rotates
around the center support 12 via a motor 40 and gears 42 and 44.
The motor 40 turns a shaft 46 including a first gear 42 that
corresponds to a second gear 44 connected to one end element 15 of
the controlled deflection roll 10. FIG. 3 shows the gears 42 and 44
as spur gears however other gear configurations can be used, such
as two helical gears. The motor 40 rotates the rotatable roll shell
14 around roller bearings 48 that extend around the center support
12 at both end elements 15 of the rotatable roll shell 14. The
center support 12 does not rotate and is fixed to a support 50 at
each end of center support 12. The end elements 15 are desirably
sealed to avoid leaking the heat transfer fluid 28.
[0033] As the rotatable roll shell 14 rotates around the center
support 12, the rotatable roll shell 14 produces drag forces that
cause the heat transfer fluid 28 to flow in the same
circumferential direction. The resulting flow of the heat transfer
fluid 28 has characteristics described by Couette flow dynamics.
"Couette flow" refers to the movement of a fluid between two
surfaces, wherein at least one surface is moving. The heat transfer
fluid 28 in contact with the rotatable roll shell 14 moves in a
direction of rotation of the rotatable roll shell 14. The heat
transfer fluid 28 in contact with the center support 12, or other
stationary surfaces within the chamber 26, does not move with the
same velocity, if at all, as the heat transfer fluid 28 toward the
rotatable roll shell 14 due to the viscosity of the heat transfer
fluid 28. The result is a gradient of circumferential flow velocity
of the heat transfer fluid 28 between the rotatable roll shell 14
and the center support 12.
[0034] The dimensions of the annulus of chamber 26, as well as the
geometry of any mixing fins, can affect the amount of turbulence in
the flow of the heat transfer fluid 28. In addition, the dimensions
of the annulus of chamber 26 can affect the motor power required to
rotate the rotatable roll shell 14, as the degree of turbulence of
the heat transfer fluid will affect the required motor power. A
smaller dimensioned annulus can cause a laminar flow of the heat
transfer fluid 28. Oppositely, a larger dimensioned annulus allows
for a more turbulent flow. Laminar flow of the heat transfer fluid
reduces the power necessary to rotate the rotatable roll shell 14
as compared to turbulent flow. Turbulent flow, however, has the
advantage of more efficient heat transfer from the heating elements
30 to the heat transfer fluid 28, as well as from the heat transfer
fluid 28 to the rotatable roll shell 14. Also, the motor power
needed to shear the heat transfer fluid 28 typically results in an
amount of heat energy in the heat transfer fluid 28. Thus, the
controlled deflection roll 10 can include various annulus
configurations including smaller annulus dimension in areas of
chamber 26 for reducing the required motor power and larger annulus
dimensions in other areas of chamber 26 to promote efficient heat
transfer. In one embodiment of this invention, a larger dimensioned
annulus of chamber 26 is used in combination with a heater element
30 to promote efficient heat transfer through turbulent flow of the
heat transfer fluid 28. The dimensions of the annulus of chamber 26
can be controlled by varying the size of the components of the
controlled deflection roll 10 within chamber 26, such as the size
and shape of the center support 12 and heater elements 30.
[0035] Discontinuous surfaces, such as fins extending from a
surface within the chamber 26 can also be used to create or enhance
flow turbulence in the annulus. In one embodiment of this
invention, the controlled deflection roll 10 includes at least one
heater element 30 having fins which increase turbulent flow over
the at least one heater element 30. The fins of one embodiment of
this invention have a height of about 0.63 centimeters, and are
suitably about 0.3 to 1.5 centimeters.
[0036] FIG. 2 shows the heater elements 30 including a plurality of
angled fins 34. The controlled deflection roll 10 in FIG. 2 rotates
in a direction shown by the arrows A. The rotation of the rotatable
roll shell 14 causes the heat transfer fluid to flow in a similar
rotational direction shown by arrows B. The angled fins 34 change
in the direction of the flow as shown by the arrows C. The angled
fins 34 cause turbulence in the flow of the heat transfer fluid 28
and direct the flow in a helical pattern in a direction towards one
end of the chamber 26. The helical flow resulting from angled fins
34 provides efficient heating over a length of the rotatable roll
shell 14. In on embodiment of this invention the angle of the
angled fins 34 are about 0 to 80 degrees from a line parallel to
the center support 12, more suitably about 30 to 70 degrees, and
desirably about 40 to 60 degrees. The center support 12 can also
include fins for promoting turbulent flow. As shown in FIG. 1, the
fins on the center support 12 are angled fins 34 having a same or
different angle than the angled fins 34 on the heater elements 30.
The fins on the center support 12 can also be straight fins
parallel or perpendicular to the rotational direction of the
rotatable roll shell 14.
[0037] The angled fins 34 direct the flow of the heat transfer
fluid 28 in a helical pattern around the center support 12 from one
end of the chamber 26 to an opposite end of the chamber 26. The
controlled deflection roll 10 shown in FIG. 1 includes a heat
transfer fluid passage 36. As shown in FIG. 3, the heat transfer
fluid passage 36 extends through a length of the center support 12
from at least one first opening 35 between the center support 12
and the end element 15 proximate to one end of the chamber 26 to at
least one similar second opening 37 at the opposite end of the
chamber 26. The heat transfer fluid 28 can be directed axially to
one end of the chamber 26 by the angled fins 34. Reaching the end
of the chamber 26 the heat transfer fluid enters the first opening
35 of the heat transfer fluid passage 36 and flows through the
passage 36 towards the opposite end of the chamber 26 and reenters
the chamber 26 at the second opening 37 of the heat transfer fluid
passage 36. The heat transfer fluid passage 36 allows for a
continuous helical flow of heat transfer fluid 28 through chamber
26.
[0038] While in the foregoing specification this invention has been
described in relation to certain preferred embodiments thereof, and
many details have been set forth for purpose of illustration, it
will be apparent to those skilled in the art that the invention is
susceptible to additional embodiments and that certain of the
details described herein can be varied considerably without
departing from the basic principles of the invention.
* * * * *