Enclosed extended nip press apparatus with inflatable seals and barbs

An enclosed extended nip press apparatus is disclosed for pressing water from a formed web. The apparatus includes a frame and a backing roll rotatably secured to the frame. A press member cooperates with a backing roll for defining therebetween an extended nip for the passage therethrough of the formed web. A press blanket extends in a closed loop through the nip, the blanket having a first and a second lateral edge and an inner and an outer surface. A first and a second head are rotatably secured to the press member with the first and second heads being disposed adjacent to and cooperating with the first and the second edges respectively of the blanket. The first and the second heads define first and second annular channels respectively for the reception therein of the first and the second lateral edges respectively of the blanket. A first and a second annular seal are disposed within respectively the first and the second channels with the seals contacting the respective edges of the blanket. A first and second plurality of barbs extend from the first and the second channels respectively such that the first plurality of barbs extend towards and engage the first lateral edge of the blanket and are disposed on the opposite surface of the blanket relative to the first seal. The second plurality of barbs extend towards and engage the second lateral edge of the blanket. The second plurality of barbs are disposed on the opposite surface of the blanket relative to the second seal so that during use of the apparatus, lateral movement of the edges of the blanket relative to the heads is inhibited.

BACKGROUND OF THE INVENTION 
1. FIELD OF THE INVENTION 
The present invention relates to an enclosed extended nip press apparatus 
for pressing water from a formed web. 
More particularly, the invention relates to a seal for sealing the lateral 
edges of a press blanket during lateral movement thereof. 
2. INFORMATION DISCLOSURE STATEMENT 
A typical extended nip press includes a backing roll and a cooperating 
press shoe defining therebetween an extended nip. A press blanket extends 
in an endless loop through the nip and a lubricant is supplied between the 
press shoe and an inner surface of the press blanket in order to permit 
the blanket to move relative to the shoe through the extended nip so that 
the blanket moves contiguously with a formed web through the nip. 
At relatively low operational speeds, lubrication of the press blanket 
presents few problems. However, at high operational speeds, particularly 
above 3,000 feet per minute, there exists a tendency for oil mist to be 
generated within the loop of the press blanket. Such oil mist tends to 
settle on ancillary equipment including hand rails and access walkways. 
Additionally, there exists the possibility of oil contaminating the formed 
web on the opposite side of the blanket. 
In view of the aforementioned problems, many proposals have been made in an 
attempt to completely enclose the press blanket of an extended nip press. 
Although the end sealing of such impervious press blanket would present no 
problem if the blanket remained cylindrical in use, such is not the case. 
Because of the inherent apple-shaped side-elevational configuration 
attained by the press blanket in use of the extended nip press, sealing of 
the lateral edges of the blanket poses relatively complex sealing 
problems. 
In West German Published Application No. DE3338487, inflatable seals are 
mounted on rotatable heads such that the seals support the inner surface 
of the blanket adjacent to the lateral edges thereof. 
Although the aforementioned arrangement permits movement of the lateral 
edges of the blanket through the extended nip due to the compressibility 
of the inflatable seals, there exists the tendency for the lateral edges 
of the blanket to wander relative to the area of contact with the 
respective inflatable seal. 
U.S. Pat. No. 4,625,376 to Schiel et al sought to overcome the 
aforementioned problem by the provision of a relatively complex sealing 
arrangement which included providing a plurality of tongues cut in the 
lateral edges of the blanket, such tongues being folded radially inward 
and clamped to the rotating heads. 
The present invention provides a simple means for securing the lateral 
edges of a press blanket against lateral wandering thereof while providing 
positive sealing against leakage of lubricating oil or mist between the 
lateral edges of the press blanket and the rotating heads. 
Accordingly, the present invention provides a significant improvement over 
the prior art arrangements and makes a considerable contribution to the 
enclosed extended nip press apparatus art. 
Another object of the present invention is the provision of an enclosed 
extended nip press apparatus which includes a first and a second plurality 
of barbs which extend from first and second channels respectively defined 
by the heads for engaging the lateral edges of the blanket so that during 
use of the apparatus, lateral movement of the edges of the blanket 
relative to the heads is inhibited. 
Another object of the present invention is the provision of an extended rip 
press apparatus in which each of the heads defines a circumferential rim, 
an extension rim extending radially outward from the circumferential rim 
and a cylindrical rim secured to the first extension rim and disposed 
coaxially and spaced relative to the circumferential rim such that the 
circumferential rim, the extension rim, and the cylindrical rim define 
therebetween the respective channels for the reception therein of the 
lateral edges of the blanket. 
Another object of the present invention is the provision of annular seals 
disposed within the channels, the seals being disposed on the opposite 
side of the lateral edges of the blanket relative to the plurality of 
barbs so that lateral movement of the lateral edges of the press blanket 
is inhibited. 
Another object of the present invention is the provision of an extended nip 
press apparatus in which each of the heads includes a pair of sectors, the 
sectors being pivotally secured relative to each other about a pivotal 
axis extending diametrically across the respective head such that outward 
pivoting of the sectors about the pivotal axis permits release of the 
respective lateral edge of the blanket from the associated plurality of 
barbs. 
Another object of the present invention is the provision of an extended nip 
press apparatus in which the annular seals are inflatable so that 
inflation of the seals urges the lateral edge of the blanket into locking 
engagement with the associated plurality of barbs. 
Other objects and advantages of the present invention will be readily 
apparent to those skilled in the art by consideration of the detailed 
description contained hereinafter taken in conjunction with the annexed 
drawings. 
SUMMARY OF THE INVENTION 
The present invention relates to an enclosed extended nip press apparatus 
and method for pressing water from a formed web. The apparatus includes a 
frame and a backing roll rotatably secured to the frame. A press member 
cooperates with the backing roll for defining therebetween an extended nip 
for the passage therethrough of the formed web. A press blanket extends in 
a closed loop through the nip, the blanket having a first and a second 
lateral edge and an inner and an outer surface. A first and a second head 
are rotatably secured to the press member with the first and second heads 
being disposed adjacent to and cooperating with the first and the second 
edges respectively of the blanket. The first and second heads define first 
and second annular channels respectively for the reception therein of the 
first and second lateral edges respectively of the blanket. A first and a 
second annular seal are disposed within the respective first and second 
channels such that the seals contact the respective edges of the blanket. 
A first and a second plurality of barbs extend from the first and the 
second channels respectively such that the first plurality of barbs extend 
towards and engage and penetrate the first lateral edge of the blanket and 
are disposed on the opposite surface of the blanket relative to the first 
seal. The second plurality of barbs extend towards and engage and 
penetrate the second lateral edge of the blanket. The second plurality of 
barbs are disposed on the opposite surface of the blanket relative to the 
second seal so that during use of the apparatus, lateral movement of the 
edges of the blanket relative to the heads is inhibited. 
In a more specific embodiment of the present invention, the press member 
includes a housing which defines a cylinder, the cylinder being 
controllably connected to a source of hydraulic pressure. An elongate 
pressing shoe slidably cooperates with the cylinder such that when the 
cylinder is connected to the source of hydraulic pressure, the shoe is 
urged towards the backing roll for pressing water from the web. 
In one embodiment of the present invention, the blanket is vented, and in a 
more specific embodiment of the present invention, the blanket defines a 
plurality of machine direction grooves for assisting drainage of water 
pressed from the formed web during passage of the web through the extended 
nip. 
In one embodiment of the present invention, the blanket is fabricated from 
a resin binder with randomly oriented fibers dispersed therein. 
In the present invention, the inner surface of the blanket cooperates with 
and moves relative to the elongate pressing shoe. 
The first and the second heads are of disc-shaped configuration with the 
heads rotating about a common axis disposed parallel and spaced relative 
to the rotational axis of the backing roll, the first head having a 
diameter substantially the same as the diameter of the second head. 
In a preferred embodiment of the present invention, each of the heads 
includes a circumferential rim disposed coaxially relative to a common 
rotational axis of the heads, a first extension rim extending radially 
outward from the circumferential rim, and a cylindrical rim secured to the 
extension rim and disposed coaxially and spaced relative to the 
circumferential rim such that the circumferential rim, the extension rim 
and the cylindrical rim define therebetween a channel for the reception 
therein of the receptive lateral edge of the blanket. 
In one embodiment of the present invention, each of the heads includes a 
pair of sectors. Each of the sectors are pivotally secured relative to 
each other about a pivotal axis extending diametrically across the 
respective head such that outward pivoting of the sectors about the 
pivotal axis permits release of the respective lateral edge of the blanket 
from the plurality of barbs. 
In a preferred embodiment of the present invention, the annular seals are 
inflatable with the first seal being disposed within a first channel such 
that the first seal contacts a first circumferential rim, a first 
extension rim and the inner surface of the blanket. The second seal is 
disposed within a second channel of the head such that the second seal 
contacts the second circumferential rim, a second extension rim and the 
inner surface of the blanket. 
Furthermore, the first plurality of barbs extend from the first cylindrical 
rim towards the first extension rim while the second plurality of barbs 
extend from the second cylindrical rim towards the second extension rim 
such that the first and the second plurality of barbs lock the respective 
edges of the blanket within the first and the second channels 
respectively. 
Many modifications and variations of the present invention will be apparent 
to those skilled in the art by a consideration of the detailed description 
contained hereinafter taken in conjunction with the annexed drawings 
showing a preferred embodiment of the present invention. Such 
modifications and variations which include the provision of a hydrostatic 
shoe or a hybrid hydrostatic and hydrodynamic shoe do not depart from the 
spirit and scope of the present invention as defined by the appended 
claims.

DETAILED DESCRIPTION OF THE DRAWINGS: 
FIG. 1 is a side-elevational view of an enclosed extended nip press 
apparatus generally designated 10 according to the present invention for 
pressing water from a formed web W. The apparatus 10 includes a frame 12 
and a backing roll 14 rotatably secured to the frame 12. A press member 
generally designated 16 cooperates with the backing roll 14 for defining 
therebetween an extended nip generally designated N for the passage 
therethrough of the formed web W. A press blanket 18 extends in a closed 
loop through the nip N. The blanket 18 has a first and a second lateral 
edge 20 and 22 respectively and an inner and an outer surface 24 and 26 
respectively. 
A first and a second head 28 and 30 respectively are rotatably secured to 
the press member 16. The first and the second heads 28 and 30 respectively 
are disposed adjacent to and cooperate with the first and the second edges 
20 and 22 respectively of the blanket 18. 
The first and the second heads 28 and 30 define first and second annular 
channels 32 and 34 respectively for the reception therein of the first and 
the second lateral edges 20 and 22 respectively of the blanket 18. 
A first and a second annular seal 36 and 38 respectively are disposed 
within the first and the second channels 32 and 34. The seals 36 and 38 
contact the respective edges 20 and 22 of the blanket 18. 
FIG. 2 is an enlarged fragmentary sectional view of the first and second 
heads 28 and 30, and shows a first and a second plurality of barbs 40 and 
42 respectively extend from the first and the second channels 32 and 34 
respectively such that the first plurality of barbs 40 extend towards and 
engages and penetrates the first lateral edge 20 of the blanket 18 and are 
disposed on the opposite surface 26 of the blanket 18 relative to the 
first seal 36. 
The second plurality of barbs 42 extend towards and engages and penetrates 
the second lateral edge 22 of the blanket 18. The second plurality of 
barbs 42 are disposed on the opposite surface 26 of the blanket 18 
relative to the second seal 38 so that during use of the apparatus 10, 
lateral movement of the edges 20 and 22 of the blanket 18 relative to the 
heads 28 and 30 respectively is inhibited. 
More specifically, the press member 16 includes a housing 44 shown in FIG. 
1 defining a cylinder 46. The cylinder 46 is controllably connected as 
indicated by 48 to a source of hydraulic pressure 50. An elongate pressing 
shoe 52 slidably cooperates with the cylinder 46 such that when the 
cylinder 46 is connected to the source of hydraulic pressure 50, the shoe 
52 is urged towards the backing roll 14 for pressing water from the web W. 
In a preferred embodiment of the present invention, the blanket 18 is 
vented and more specifically, as shown in FIG. 2, the blanket 18 defines a 
plurality of machine direction grooves 54, 55, 56, 57, 58, 59, 60 and 61 
for assisting drainage of water pressed from the formed web W during 
passage of the web W through the extended nip N. 
The blanket 18 preferably is fabricated from a resin binder with randomly 
oriented fibers dispersed therein as taught in co-pending patent 
application no. 07/179,086. All the subject-matter of co-pending patent 
application no. 07/179,806 is incorporated herein by reference. 
The inner surface 24 of the blanket 18 cooperates with and moves relative 
to the elongate pressing shoe 52. 
As shown particularly in FIG. 1 the first and the second heads 28 and 30 
respectively are of disc-shaped configuration. The heads 28 and 30 rotate 
about a common axis A which is disposed parallel and spaced relative to 
the rotational axis RA of the backing roll 14. The first head 28 has a 
diameter D which is substantially the same as the diameter D1 of the 
second head 30. 
As shown in FIG. 2, the first head 28 also includes a first circumferential 
rim 64 which is disposed coaxially relative to the common axis A. A first 
extension rim 66 extends radially outward from the first circumferential 
rim 64. A first cylindrical rim 68 is secured to the first extension rim 
66 and is disposed coaxially and spaced relative to the first 
circumferential rim 64 such that the first circumferential rim 64, the 
first extension rim 66, and the first cylindrical rim 68 define 
therebetween the first channel 32 for the reception therein of the first 
lateral edge 20 of the blanket 18. 
Furthermore, the second head 30 includes a second circumferential rim 70 
which is disposed coaxially relative to the common axis A. A second 
extension rim 72 extends radially outward from the second circumferential 
rim 70 and a second cylindrical rim 74 is secured to the second extension 
rim 72 and is disposed coaxially and spaced relative to the second 
circumferential rim 70 such that the second circumferential rim 70, the 
second extension rim 72 and the second cylindrical rim 74 define 
therebetween the second channel 34 for the reception therein of the second 
lateral edge 22 of the blanket 18. 
FIG. 3 is a left-side view of the head 28 shown in FIG. 1 in which the 
first head also includes a first and a second sector 76 and 78 
respectively. The sectors 76 and 78 are pivotally secured relative to each 
other about a pivotal axis PA which extends diametrically across the first 
head 28 such that outward pivoting of the sectors 76 and 78 about their 
pivotal axis PA, is permitted. FIG. 4 shows the sectors 76 and 78 in a 
locked disposition. FIG. 5 shows the sectors 76 and 78 in an outwardly 
pivoted disposition permitting release of the first lateral edge 20 of the 
blanket 18 from the first plurality of barbs 40. 
As shown in FIG. 5, the second head 30 also includes a third and fourth 
sector 80 and 82 respectively. The third and fourth sectors 80 and 82 are 
pivotally secured relative to each other about a further pivotal axis FPA 
which extends diametrically across the second head 30 such that outward 
pivoting of the third and fourth sectors 80 and 82 about the further 
pivotal axis FPA, as shown in FIG. 5, permits release of the second 
lateral edge 22 of the blanket 18 from the second plurality of barbs 42. 
As shown in FIG. 2, the annular seals 36 and 38 are inflatable by means of 
valves 84, 86. The first seal 36 is disposed within the first channel 32 
such that the first seal 36 contacts the first circumferential rim 64, the 
first extension rim 66 and the inner surface 24 of the blanket 18. The 
second seal 38 is disposed within the second channel 34 such that the 
second seal 38 contacts the second circumferential rim 70 the second 
extension rim 72 and the inner surface 24 of the blanket 18. 
The first plurality of barbs 40 extend from the first channel 32 towards 
the outer surface 26 of the blanket 18. The second plurality of barbs 42 
extend from the second channel 34 towards the outer surface 26 of the 
blanket 18. 
More specifically, as shown in FIG. 2, the first plurality of barbs 40 
extend from the first cylindrical rim 68 towards the first extension rim 
66. Furthermore, the second plurality of barbs 42 extend from the second 
cylindrical rim 74 towards the second extension rim 72 such that the first 
and the second plurality of barbs 40 and 42 respectively lock the 
respective edges 20 and 22 of the blanket 18 within the first and the 
second channels 32 and 34 respectively. 
The present invention provides a simple means for locking the respective 
lateral edges of a press blanket to the respective rotating heads of an 
extended nip press so that lateral movement or wandering of the blanket 
relative to the heads is inhibited while maintaining a seal against the 
escape of oil mist between the moving blanket and heads.