Self-loading controlled deflection roll

A self-loading controlled deflection roll for forming a pressure nip with another roll has at least one support shoe mounted in a stationary support shaft for controlling the deflection of the roll shell in the direction of the nip. At either end of the controlled deflection roll, a pair of opposed guide shoes are slidably mounted on the stationary support shaft to apply pressure against the roll shell to stabilize the position of the roll shell relative to the stationary shaft. At least one guide shoe on either end of the roll is equipped with a compensating piston to permit its face surface to move radially outwardly relative to the guide shoe support on the stationary shaft. The guide shoes slidably reciprocate in planes parallel to the plane of the nip through the longitudinal axis of the roll and provide opposed, equal stabilization forces at substantially right angles to the plane of the nip. The guide shoes also have axially extending pads for bearing against annular end surfaces on the roll shell to maintain the roll shell fixed in the longitudinal direction relative to the support shaft during operation.

BACKGROUND OF THE INVENTION 
1. FIELD OF THE INVENTION 
This invention relates to a controlled deflection roll such as is used in 
the press and calender sections of a papermaking machine. More 
particularly, this invention relates to a self-loading type of controlled 
deflection roll wherein the roll shell can translate relative to the 
longitudinal axis of the roll. Still more particularly, this invention 
relates to a self-loading controlled deflection roll wherein the roll 
shell is both rotatably and positionably supported solely by hydraulically 
actuated shoes on a stationary shaft. Even still more specifically, this 
invention relates to an adjustably positionable side guide shoe apparatus 
for stabilizing the roll shell in a self-loading type of controlled 
deflection roll. 
2. DESCRIPTION OF THE PRIOR ART 
A prior self-loading type of controlled deflection roll is described and 
illustrated in Biondetti, U.S. Pat. No. 3,885,283. In this patent, the 
roll shell is hydrostatically supported in the direction of its nip with 
another roll by a plurality of shoes which are aligned longitudinally 
along the length of the stationary support shaft. A pair of collars, each 
having a pair of flat, parallel surfaces, are disposed at either end of 
the roll shell to slide over corresponding surfaces on the roll shaft to 
permit the roll shell to translate reciprocally in the direction of its 
nip with another roll while maintaining the roll shell in a fixed position 
relative to the shaft in a plane perpendicular to a plane through the nip 
with another roll. The roll shell rotates on bearings mounted to each of 
the collars. 
Other patented controlled deflection rolls utilize magnets to compensate 
and adjust for deflection of a rotating, bearing supported roll shell over 
a stationary support shaft. Still other patents relating to self-loading 
controlled deflection rolls disclose support of the roll shell relative to 
the shaft by a plurality of circumferentially spaced shoes which position 
the rotating roll shell at predetermined radial positions about the roll 
shaft according to the circumferential position of the roll shaft. 
In Arav, U.S. Pat. No. 4,821,384, diametrically opposed nip loading shoes 
are positioned in the stationary shaft of a controlled deflection roll to 
move the roll shell radially inwardly and outwardly in opposed directions 
relative to the shaft. In some embodiments, stabilizing shoes are located 
circumferentially about the roll shaft outside of the plane of the nip 
loading shoes which actuate the roll shell. The stabilizing shoes move 
outwardly relative to the longitudinal axis of the roll shaft and also 
slide along flat surfaces on the roll shaft parallel to the plane of the 
support shoes and the nip. 
Regardless of the configuration of prior self-loading controlled deflection 
rolls, none of them can provide constant roll shell stabilizing force in a 
configuration where the roll shell is not mounted on bearings, or where 
there are dimensional variations in the roll, or both, particularly in 
rolls utilizing hydraulically actuated stabilizing shoes. Thus, the prior 
self-loading type of controlled deflection rolls cannot accommodate 
dimensional variations between the roll shell and stationary shaft due to 
manufacturing tolerances and temperature changes which affect different 
components in different degrees depending on the co-efficient of thermal 
expansion of their materials. For example, in some prior designs of 
self-loading rolls, the pressurized hydraulic fluid could escape more 
quickly from one stabilizing shoe, or at the interface of a stabilizing 
shoe and the supporting roll shaft at one location than at another. This 
could cause variations in the stabilizing pressures provided between the 
shaft and inner surface of the roll shell and thus permit the roll shell 
to shift its radial position laterally of the plane of the nip, or even to 
oscillate relative to the shaft. 
Further, in some instances, such as when the tolerances become negative, 
stabilizing shoes interposed between the shaft and roll shell can become 
wedged between the shaft and roll shell and act as a brake to the 
detriment of the intended method of operation. 
SUMMARY OF THE INVENTION 
The disadvantages and deficiencies of the prior types of self-loading 
controlled deflection rolls equipped with means to stabilize roll shell 
motion relative to the roll shaft have been obviated by this invention. No 
bearings are required or used to rotatably support the roll shell about 
the roll shaft. This permits reduced rotational friction as well as 
operation at temperatures higher than those which can be sustained by 
bearings. In this roll, a pair of opposed guide shoes are provided at 
either end of the controlled deflection roll to stabilize the roll shell. 
They are mounted on the stationary roll shaft to move in parallel, spaced 
planes in the direction of roll shell support shoes which move the roll 
shell translationally relative to the shaft into and out of nipping 
engagement with another roll. All of the support and guide shoes are 
hydraulically actuated and have faces adapted to hydrostatically or 
hydrodynamically support a film of lubricating oil at their interface with 
the roll shell. The roll shell is thus solely supported at each end of the 
roll by three or four hydraulically actuated shoes circumferentially 
spaced about the shaft. In addition, one of the guide shoes at either end 
of the roll is equipped with a compensating piston to allow for variations 
in dimensions between parts, whether due to manufacturing tolerances or to 
changes due to temperature. The guide shoes can thereby uniformly 
stabilize the location of the roll shell in a direction substantially 
transverse to the direction of movement of the roll shell into and out of 
nipping engagement with another roll. 
This invention permits the guide shoes to provide opposed stabilizing 
pressure of a constant force against the roll shell regardless of the 
position of the roll shell radially toward or away from the nip with 
another roll, or regardless of small movements of one, or the other, of 
the guide shoes radially relative to the support shaft. The constant force 
of the guide shoes against the inner surface of the roll shell is provided 
by the function of the compensating piston which maintains the thickness 
of the pressurized film of hydraulic fluid essentially the same over the 
faces of both guide shoes at all times during operation. Since the face 
area of both of the opposed guide shoes is the same, their stabilizing 
force exerted against the roll shell will also be the same regardless of 
slight radial movement of the compensating piston relative to the roll 
shaft. Naturally, it is recognized that if the stabilizing faces of the 
guide shoes were of different areas, the stabilizing forces exerted by 
opposing guide shoes would be the same with different unit pressures over 
their surfaces. 
Accordingly, it is an object of this invention to provide a self-loading 
type of controlled deflection roll which does not utilize roller bearings 
to rotatably support and stabilize the roll shell. 
Another object of this invention is to provide a self-loading type of 
controlled deflection roll having guide shoes for providing stabilizing 
force against the roll shell. 
Still another object of this invention is to provide a self-loading 
controlled deflection roll having guide shoe apparatus which can 
accommodate dimensional variations in the apparatus due to manufacturing 
tolerances and thermal expansion while providing substantially uniform 
stabilizing support of the rotating roll shell. 
Another object of this invention is to provide a self-loading type of 
controlled deflection roll which can be operated at high temperatures or 
reduced rotational friction, or both. 
A feature of this invention is the provision of a compensating piston 
within at least one of each pair of guide shoes at each end of the roll. 
Another feature of this invention is that concentricity of the rotating 
roll shell relative to its axis of revolution is maintained with great 
accuracy. 
An object, advantage and feature of this invention is that substantially 
equal, opposed stabilizing forces are applied to substantially diametrally 
located positions on the inner surface of the roll shell regardless of 
variations in the internal dimensions of the roll due to manufacturing 
tolerances and thermal expansion. 
Another feature of this invention is that the face area of the opposed 
guide shoes can be made unequal to provide for a specific external side 
load such as a gearbox. 
These, and other objects, features and advantages of this invention will 
become readily apparent to the artisan upon reading the description and 
claims of this invention in conjunction with the attached drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As shown in FIG. 1, a self-loading controlled deflection roll 10 has a 
center stationary support shaft 12 and a hollow cylindrical roll shell 14. 
In such a self-loading roll, the roll shell is intended to be moved 
translationally into nipping engagement with another roll 4 along a nip 
line of contact N in a nip plane 15 through the nip line N and the 
longitudinal axis 16 of the roll 10, which nip plane is shown more clearly 
in FIG. 3. In other words, in FIG. 1, the nip plane is shown as a line 
coincident with the longitudinal axis 16, while in FIG. 3, the nip plane 
15 is shown as a vertical line having both the nip line N and the 
longitudinal axis 16 in the plane. 
In the following discussion, corresponding elements in the various 
configurations or embodiments in the different figures, particularly FIGS. 
5, 6 and 7, will be correspondingly numbered with different letter 
suffixes used to differentiate between similar elements in different 
figures. In the same manner, corresponding elements in the same component 
are designated with the same numeral, but with a different number of prime 
superscripts. 
Referring to FIGS. 1, 2, 3 and 3A, support shaft 12 has one or more 
hydraulic chambers, or cylinders, 18, 19 formed in it on opposed sides to 
receive the piston ends 20, 21 of opposed support shoes 22, 24 which 
extend toward and away from nip N along the nip plane. These support shoes 
are hydraulically actuated by pressurized hydraulic fluid which is 
supplied to conduits 26, 28 and then to the chambers from an outside 
source, such as a pump (not shown) via central load shoe conduits 30, 32. 
Support shoes 22, 24 have support faces 33, 35 which bear against, and 
thus support, the roll shell and load it into and out of nipping 
engagement along the nip plane by supplying pressurized hydraulic fluid to 
the one or more support shoes 22, 24 along one side, such as the lower 
side shown in FIG. 3A, while permitting the evacuation of pressurized 
fluid from the hydraulic chamber, or cavities, supplying the single 
support shoe 22 shown in the upper side of the roll shown in FIG. 3A. It 
is not illustrated, but well-known to the artisan, to replace the single 
support shoes 22, 24 shown with multiple, longitudinally aligned, shoes 
which may be either the hydrostatic or hydrodynamic type. 
The upper support shoe 22 shown in FIG. 1 is a one piece shoe which extends 
for essentially the entire effective face length of the roll shell. Its 
support face contains at least four cavities, or recessed pockets 23, 23', 
23'', 23''', which receive pressurized hydraulic fluid via throttling 
conduits 25, 25', 25'', 25''' linking these pockets with the chamber 18 
beneath the piston end 20 of the support shoe 22. Lower support shoe 24 
has similar pockets 27 in its face which are supplied with hydraulic 
lubricating fluid via similar conduits 29 from a similar chamber 19. 
As shown more clearly in FIG. 1, the support shaft 12 has laterally 
extending side bodies 34, 36 which extend substantially perpendicular to 
the nip plane. They are used in conjunction with longitudinally extending 
positioning pistons bearing against guide shoes as will be described 
subsequently. 
Near either end of the roll shell, spaced inwardly thereof, are a pair of 
opposed guide shoes 38, 40 and 42, 44. A corresponding pair of parallel 
planar guide surfaces 46, 48 and 50, 52 are formed in the support shaft 
and are arrayed in planes parallel with the nip plane. A guide shoe 
conduit 54 (FIG. 5) within the support shaft 12 is linked with each of the 
guide shoes 38, 40, 42, 44 by hydraulic feed lines 55, 55' to supply 
pressurized hydraulic fluid to each of the guide shoes from a pressurized 
source, such as a pump (not shown). 
As shown in FIGS. 4, 4A and 4B, each of the guide shoes has a guide face 57 
in which a plurality of recessed pockets 58, 58', 58'', 58''' are formed. 
On one end of each guide shoe, that is, the end which extends inwardly 
toward the center of roll 10, is a pad 60 having a bore 62 extending 
partially through from its outer end. On the other end of the guide shoes, 
on the end facing outwardly toward the ends of the roll, are a pair of 
adjacent, laterally spaced pads 64, 64', each of which includes a recessed 
pressure cavity 66, 66'. 
Pressurized hydraulic fluid is supplied to cavities 66, 66' via throttling 
conduits 93, 93', and to pockets 58, 58', 58'', 58''' via throttling 
conduits 104, 104', 104'', 104''' to provide lubrication to their 
interfaces with contiguous surfaces of the roll. 
As shown more clearly in FIG. 1, the guide shoes 42, 44 on the rear end 6 
of the roll 10 are equipped with pistons 68, 70 which are normally 
bottomed out in their bore in their pad. In the guide shoes 38, 40 on the 
front end 8 of the roll, pistons 72, 74 are shown extended somewhat in the 
bores in their pads. The faces 71, 71', 71'', 71''' of these pistons have 
chambers or pockets 73, 73', 73'', 73''' which are hydraulically actuated 
and bear against the side bodies 34, 36 of support shaft 12. 
The roll shell is therefore supported in the nip plane solely by upper and 
lower support shoes 22, 24 which extend substantially for the effective 
face length of the roll shell. At either end of the roll, a flat, annular 
disc 76, 76' is secured to a cylindrical collar 77, 77' by pins 78, 78' 
The collar is bolted to the ends of the roll shell by a plurality of cap 
screws 80, 80'. At the distal end of each collar 77, 77', a bearing 82, 
82' is located to position the collar from an annular head 84, 84'. 
Axially inwardly from each bearing is a seal 86, 86' which has an outer, 
cylindrical surface 87, 87' which bears against the cylindrical inner 
surface of the head 84, 84'. Seals 86, 86' also have parallel faces 88, 
88', 90, 90' which engage disc-like rings 92, 92', 94, 94' which are 
attached to the support shaft. The cylindrical surfaces 87, 87' of seals 
86, 86' thus slidingly engages the cylindrical inner surface of each head 
84, 84' to seal that interface in the axial direction, while the 
interfaces between seal faces 88, 88', 90, 90' and annular rings 92, 92', 
94, 94' seal against movement of the roll shell translationally relative 
to shaft 12. 
Referring to FIG. 5, one guide shoe assembly 39 has a guide shoe 38 having 
a stabilizing face 56 for engaging the inner surface 17 of the roll shell 
and a portion 72 having a support face 96 for engaging the guide surface 
46 on the support shaft 12. On the other side of the support shaft is a 
guide shoe assembly 41 which comprises an outer guide shoe member 40 
(shown in FIGS. 4, 4A, 4B) having a stabilizing face 57 for engaging the 
inner surface of the roll shell and a compensating piston shoe member 75 
having a support face 98 for engaging the guide surface 48 on the support 
shaft 12 which is parallel to the guide surface 46 on the other side of 
the support shaft. 
Within each of the outer, stabilizing faces 56, 57 of each guide shoe 38, 
40 are one or more recessed pockets 59, 59', 58, 58', respectively, and 
within each of inner, support faces 96, 98 are one or more recessed 
pockets 61, 61', 63, 63' for receiving pressurized hydraulic fluid to 
provide lubrication and pressure to the respective interfaces. These 
pockets, or cavities, are supplied by throttling conduits, such as 
hydraulic feed lines 100, 100', 102, 102', 104, 104', 106, 106', which are 
in turn fed from the central hydraulic conduit 54 and lines 55, 55' via 
tubes 108, 108' which are pivotally mounted in spherical bushings 110, 
110' linking central conduit 54 with a chamber 114, 116 in, or beneath, 
shoes 38, 40. 
It can be seen that chamber 116 provides a source of pressurized hydraulic 
lubricant to shoe 40, and to the bore chamber 81 intermediate the outer 
guide shoe member 40 and compensating shoe member 75 to provide hydraulic 
pressure and force to the underside of outer guide shoe member 40 relative 
to compensating shoe member 75. This will increase or decrease the gap 
118, which is the interface between members 40, 75, as guide shoe 40 moves 
relative to compensating shoe 75 due to changes in the dimensions of the 
various components of the roll due to both thermal expansion of the 
members having different coefficients of expansion, as well as due to 
dimensional variations due to differences in manufacturing tolerances. 
Chambers 114, 116 also provide lubricating fluid to the family of pockets 
58, 59, 61, 63, 66 and 73 which all function as hydrostatic bearings in a 
well-known manner. 
Referring now to FIG. 6, a roll having a different configuration of the 
guide shoe assembly 41a having the compensating piston is shown. In this 
embodiment, chamber 114a essentially comprises a relief in shoe 38a. An 
extension 55aa of conduit 55a with the throttling hydraulic lines 100a, 
100a', 102a, 102a' feeding their respective pockets in the same manner as 
described in conjunction with the embodiment shown in FIG. 5. In the guide 
shoe assembly 41a, the outer guide shoe 40a is biased radially outwardly 
relative to guide surface 48a and compensating piston member 75a by one or 
more springs 120, 120' mounted in opposed recesses in members 40a, 75a. 
This spring arrangement thus maintains the support face 57a of the guide 
shoe 40a against the inner surface of the roll shell regardless of radial 
movement of the roll shell normal to the plane 15a through the support 
shoes 22a, 24a. If strong enough, the springs themselves could provide the 
stabilizing force of the guide shoe faces against the roll shell. 
In FIG. 7, another guide shoe assembly 41b is shown which does not utilize 
springs to bias the outer guide shoe relative to the compensating piston. 
In this embodiment, chambers 116b, 116b' are supplied with pressurized 
hydraulic fluid via conduits 122, 122'. Chambers 116b, 116b', in turn, 
supply throttling lines 104b, 104b', 106b, 106b' with pressurized 
hydraulic lubricant to provide lubrication in the pockets 58b, 58b', 63b, 
63b', respectively. The hydraulic pressure in chambers 116b, 116b' thus 
operates to maintain the outer shoe member 40b biased against the inner 
surface of the roll shell while maintaining the face 98b biased against 
the support surface 48b on the roll shaft despite variations in the radial 
distance between the longitudinal axis 16 and the inner surface of the 
roll shell. 
In operation, with particular reference to FIGS. 1 and 5, pistons 68, 70, 
72, 74 are hydraulically actuated to position and maintain the roll shell 
axially relative to the center shaft by providing pressure between the 
guide shoes 38, 40, 42, 44 and the side body portions 34, 36 of the center 
shaft 12. Pistons 68, 70 are maintained in the bottoms of the bores and 
their respective pads to establish an operating position, while the 
pistons 72, 74 are pressurized in their extended position to maintain the 
established position of the roll shell axially relative to the shaft. 
Pressurized fluid is also supplied through conduits 104, 104', 104'', 
104''' and 93, 93' to their respective pockets 58, 66 to lubricate their 
interface with the roll shell (58/17) and with the disc (66/76). 
Support shoe piston members 20, 21 are actuated, or deactuated, as desired, 
to translationally position the roll shell relative to the longitudinal 
axis 16 of the roll and to bring the roll shell into, or out of, loading 
engagement with another roll along a nip line of contact N in the nip 
plane 15 which extends axially along the longitudinal axis 16 and through 
each of the support shoes 22, 24. The hydraulic pressure to, or from, 
chambers 18, 19 to pressurize or relieve the pressure on piston members 
20, 21 of the support shoes is provided through central load conduits 30, 
32 and support shoe conduits 26, 28 leading to chambers 18, 19. 
With reference to FIG. 5, the central guide conduit 54 is pressurized with 
hydraulic fluid which travels radially outwardly through feed lines 55, 
55' through hollow tubes 108, 108' to chambers 114, 116 beneath guide shoe 
assemblies 39, 41. The hydraulic fluid feed tubes 108, 108' are mounted 
with their inner ends pivotally secured in a bore 112, 112' in shaft 12 
with a spherical bushing 110, 110' to provide limited arcuate motion while 
maintaining a seal relative to the pressurized hydraulic fluid within feed 
lines 55, 55'. In a similar manner, the outer ends of the hydraulic tubes 
108, 108' are mounted in the end 72 in the guide shoe 38 and in the 
compensating piston member 75 in the guide shoe assembly 41. The inner 
ends of tubes 108, 108' are free to slide in their respective bores to 
accommodate the arcuate motion. 
Actuation of the upper or lower support shoes 22, 24 and the corresponding 
deactuation of the opposed support shoe, or shoes, causes the roll shell 
14 to move translationally in the nip plane. When this happens, in order 
to maintain the roll shell rotationally stable during operation, guide 
shoes 38, 40 must also slide up and down a corresponding distance with 
faces 96, 98 in sliding engagement with faces 46, 48 of the center shaft. 
Lubrication for this sliding movement of the guide shoe assemblies on the 
support shaft is provided by the pressurized hydraulic fluid in pockets 
61, 61', 63, 63'. In a similar manner, the lubrication for the relative 
sliding motion of the inner surface of the roll shell against the 
stabilizing faces 56, 57 of the guide shoes is provided by the pressurized 
lubricant in pockets 58, 58', 59, 59'. 
In the embodiment shown in FIG. 5, the spherical bushings in the hydraulic 
feed tubes slide axially and tilt to allow the hydraulic pressure to be 
maintained in chambers 114, 116 regardless of the translational position 
of the guide shoe assemblies 39, 41 relative to the support shaft. In 
addition, the guide shoe 40, by virtue of its slidable bore 81 over a 
piston 83 in compensating piston 75, which is sealed by ring seals 79, 
allows the guide shoe to move radially outwardly relative to the 
compensating piston 75, which increases or decreases gap 118, under the 
biasing pressure of the hydraulic fluid in chamber 116. The interface at 
gap 118 might range from metal-to-metal contact to a gap of about 0.25 cm. 
This permits the roll to accommodate slight differences in the dimensions 
and tolerances built into the components during manufacturing as well as 
those created during operation due to differences in the coefficients of 
thermal expansion of the components, such as the roll shell and roll 
shaft. Also, some movement of the roll shell relative to the roll shaft 
can be caused by operating conditions, such as the passage of a wad of 
paper through the nip or impurities in the lubrication fluid at the 
interface between the guide shoes and either the roll shell or roll shaft. 
The operation of the embodiments shown in FIGS. 6 and 7 is similar to that 
described in conjunction with the embodiment shown in FIG. 5. Thus, in the 
embodiment shown in FIG. 6, chamber 116a and the relief 114a linking 
extension 55aa within shoe 38a have diameters sufficient for them to 
remain in fluid communication with hydraulic fluid conduit 55a regardless 
of the translational position of the guide shoe assemblies 39a, 41a along 
the support surface of the roll shaft. The larger diameter of the bore 81a 
ensures that the hydraulic pressure applied to the guide shoe 40a is 
sufficient for it to be able to move radially outwardly relative to the 
compensating shoe. Springs 120, 120' bias the guide shoe 40a outwardly 
relative to the compensating shoe to maintain the guide shoe in position 
against the inner surface of the roll shell. 
In the embodiment shown in FIG. 7, hydraulic feed lines 55b, 55b' supply 
pressurized hydraulic fluid to the lubricating pockets as well as to the 
chambers 116b, 116b' in the compensating piston shoe assembly via feed 
lines 122, 122' to provide the pressure of the guide shoe on the 
compensating piston side of the apparatus against the roll shell. 
In all embodiments, the pressure applied by the guide shoe against its 
compensating piston member by means, such as the hydraulic fluid pressure 
in chamber 116, or even by springs, to produce a force of its guide shoe 
stabilizing face against the inner surface of the roll shell is balanced 
by an equal reaction force created by the resulting movement of the 
opposite inner side of the roll shell against the stabilizing face of the 
opposed guide shoe. Therefore, only one side of the roll need be equipped 
with a compensating piston guide shoe assembly. Such an assembly 41 need 
not be located at or near the ends of the roll, in which case two such 
assemblies might not be utilized. 
Accordingly, this apparatus achieves the objects of the invention and 
incorporates its features and advantages by providing opposed stabilizing 
pressure to the stabilizing shoe assemblies on either side of the roll 
shaft, preferably at either end of the roll to maintain the roll shell in 
continuous stabilized position relative to the roll shaft during 
operation. Naturally, variations within the skill of the artisan can be 
effected without departing from the spirit of the invention and scope of 
the claims. For example, it is contemplated that the opposed stabilizing 
guide shoes can be operated in conjunction with the support shoe, or 
shoes, on only one side of the roll. Thus, in some operating situations, 
support shoe 24 might be deactivated during operation and only support 
shoe 22 operating against a nip N with a roll, or other support, over 
support shoe 22. Also, it is contemplated that the stabilizing face areas 
of the guide pistons need not be the same. The laws of hydraulics can be 
utilized in a desired manner to produce the desired opposed forces against 
the inner roll face which is the only support surface contacted by all the 
support and guide elements. The principles of the roll shell stabilization 
provided by the operation of the guide shoes would remain the same.