WO2004048690A1

WO2004048690A1 - Heated controlled deflection roll

Info

Publication number: WO2004048690A1
Application number: PCT/US2003/026343
Authority: WO
Inventors: Robert James Gerndt; Jark C. Lau; John Joseph Sayovitz
Original assignee: Kimberly-Clark Worldwide, Inc.
Priority date: 2002-11-26
Filing date: 2003-08-22
Publication date: 2004-06-10
Also published as: US20040102298A1; AU2003259997A1

Abstract

A heated controlled deflection roll (10) including a center support (12) and a rotatable roll shell (14) surrounding the center support (12). A shoe assembly (20) connects the center support (12) and the inside surface (16) of the rotatable roll shell. The shoe assembly (20) includes 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) has a length substantially equal to a length of the inside surface (16) of the rotatable roll shell (14). Free space within a chamber (26) within the rotatable roll shell (14) is filled with a heat transfer fluid and heater elements (30). The heater elements (30) have angled fins (34) for directing the flow of the heat transfer fluid in a helical pattern towards one end of the rotatable roll shell (14). The heat transfer fluid returns to the opposite end of the chamber (26) through a passage (36) through the center support (12).

Description

HEATED CONTROLLED DEFLECTION ROLL

FIELD OF INVENTION 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 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.

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.

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. 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. 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. 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. 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.

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.

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.

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 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.

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.

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.

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. 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 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:

FIG. 1 shows a cross section view of a controlled deflection roll according to an embodiment of this invention.

FIG. 2 shows a partial sectional view of a controlled deflection roll according to an embodiment of this invention.

FIG. 3 shows a partial sectional view of a controlled deflection roll and frame according to an embodiment of this invention.

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

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 ran. 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.

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.

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.

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.

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®, 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.

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. 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.

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.

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.

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°C, more desirably about 100°C to 260°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. 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.

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.

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.

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.

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.

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. 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.

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.