Note: Descriptions are shown in the official language in which they were submitted.
B61~l65l4
~3~ 5~; 1
SEALING APPARAq'US FOR
SEALING A MOVABLE BLANKET
BACKGROUND OF_THE INVENTION
FIELD OF THE INVENTION
This invention relates to a sealing apparatus for
sealing a movable blanket relative to a first press member
of an extended nip press. More specifically, this in~ !
vention relates to a sealing apparatus for sealing a
movable blanket relative to a first press member of an
extended nip press wherein the first press member is of
the so-called "apple" configuration..
BACKGROUND OF THE INVENTION
Many variations of the basic extended nip press
concept have been proposed. Basically, an extended nip
press includes a first and second cooperating press
members which define therebetween an extended nip. The
arrangement is such that as the paper web passes through
such extended nip, the residence time of the paper web
~ !
between the cooperating press members is increased rela-
tive to the residence time of a more conventional nip
defined by a pair of cooperating rolls. The increased
residence time has a profound effect on the amount of
i water removed from the paper web, partially because the
water removing~pressure is exerted more gradually and for
a longer pe~iod than is the case with a conventional nip
defined by a rol] couple.
Although many different extended nip press designs
have been proposed, a particularly effective proposal was
disclosed~ in U.;S. patent numbers 4,287,021 and RE 31,923
to Justus et al. The aforementioned extende~d nip press
design has been commonly termed the "apple" design. This
B61~16514
" ~3~15~ ,
is because the lower first press m~mber resembles an apple
when viewed in a cross-machine direction.
With the so-called "apple~ extended nip press, a
major problem has been the containment of the lubricating
oil disposed between the inner surface of the blanket and
the outer surface of the apple-shaped first press member.
As the looped blanket in operation of the extended nip
press moves around the stationary first press member,
there has been a tendency for the lubricating oil to seep
laterally towards the edges of the blanket thereby permit-
ting particles of the lubricating oil to be thrown
radially outwards, thus causing possible contamination of
the treated paper web.
The present invention seeks to overcome the aforemen-
tioned problern associated with such seepage of the lu-
bricating oil and thereby provides a significant contribu-
tion to, and advancement over, the prior art proposals.
Another object of the present invention is the
provision of inflatable annular sealing means secured to
rotatable heads disposed adjacent the first and second
ends of the first press member so that when the seals are
inflated, the blanket is sealed relative to the first
press member.
Another object of the present invention is the
provision of a sealing apparatus in which when the seals
are lnflated, the blanket is permitted to rotate relative
to, and around, the first press member.
Another object of the present invention is the
provision of a sealing apparatus in which when the seals
are disposed in a deflated second position thereof, the
blanket is permitted to be moved axially relative to the
first press member for replacement of the blanket.
Another object of the present invention is the
provision of a sealing apparatus in which when the seals
--2--
e6l~l6~l4
~3~
are disposed in an inflated first and third position
thereof, the blanket is permitted to move axially relative
to the first press member while maintaining a sealing
engagement with the inner surface of the blanket.
Other objects and advantages of the present invention
will be evident to those skilled in the art by a consid-
eration of the following detailed description taken in
conjunction with the annexed drawings and from a consid-
eration of the appended claims.
SUMMARY OF THE INVENTION
.
This invention relates to a sealing apparatus and a
method for sealing a movable blanket which extends through
an extended nip defined by first and second cooperating
press members. The sealing apparatus seals the blanket
relative to, and between, a first and second end of the
first press member. The apparatus includes a first
rotatable head disposed adjacent to the first end of the
first press member. The first head is disposed coaxial
relative to the first press member. A second rotatable
head is disposed adjacent to the second end of the first
press member with the second head being disposed coaxial
relative to the first head and the first press member
respectively. A first annular seal means is disposed
between the blanket and the first head for sealing the
blanket relative to the first head. A second annular seal
; means is disposed between the blanket and the second head
;,
for sealing the blanket relative to the second head. The
arrangement is such that when the first and second seal
means are in an inflated first position thereof, the
blanket is permitted to rotate coaxially around the first
press member. When the first and second seal means are
disposed in a deflated second position thereof, the
blanket is movable axially relative to the seal means for
replacing the blanket.
-3-
B61~1~514
--`` 13~ 5~;i
In a more specific embodimen~. of the present in-
vention, the first and second heads are each of
disc-shaped configuration and are rotatable relative to
the first member. The first and second seals are fab-
ricated from an elastomeric material and are of a hollow,
toroidal configuration such that when the seals are
inflated, a sealing member of each seal is urged radially
outwardly relative to the respective head into sealing
conformity with the inner surface of the movable blanket.
A base portion of each seal is connected with a respective
head so that when the seals are inflated, the blanket is
supported by the seal members and enabled to rotate with
the heads around the stationary first press member.
Due to the elastomeric nature of the seals, any axial
and/or radial movement of the blanket relative to the
first press member can be accommodated when the seals are
inflated.
In another embodiment of the present invention, the
base portion defines a convex surface in a cross-machine
directlon and the first and second rotatable heads each
define a concave rim surface in a cross-machine direction.
The concave rim surface cooperates with the convex surface
of the base portion for permitting axial mounting of the
respective seal means onto the respective head.
In another embodiment of the present invention, the
first an~d second rotatable heads each further include a
rim portion with the rim portion of each head defining a
plurality of radial slots, A plurality of threaded
fas~teners are anchored within the base portion with the
threaded fasteners having threaded portions extending
radially inwards relative to the base portion. The
i~ arrangement is such that the inwardly extending threaded
portions cooperate with the radial slots so that when the
seal means is moved axially relative to the rim portion,
-4-
,: I
B61~1651q
~3~ 56
the threaded portions are recei~d within the radialslots. A plurality of internally-threaded members cooper-
ate with the threaded portions for anchoring the base
portion relative to the rim portion.
In each of the aforementioned embodiments, the
sealing member is movable to a compressed third position
thereof when the respective seal means is inflated. The
third position is attained during compression of the
respective seal means when that portion of the respective
seal means passes through the extended nip.
In a preferred embodiment of the present invention,
the seal means defines, in an unstressed and unbiased
disposition thereof, a cross-sectional configuration
substantially equivalent to the cross-sectional configura-
tion of the seal means when disposed in the second posi-
tion thereof. This unstressed and unbiased second dispo-
sition of the seal means with the seal means being
disposed between the first and third positions thereof, is
such that during stressing of the seal means during use of
the sealing apparatus, the life of the seal means is
extended.
In yet another embodiment of the present invention,
the first and second seal means each further include a
base portion for connecting the respective seal means to
the respective rotatable head and a sealing portion
disposed diametrically opposite to the base portion with
the sealing portion defining a plain sealing surface
disposed adjacent to an inner surface of the movable
blanket.
In another embodiment of the present invention, means
are provided for connecting a compartment defined between
the blanket, the first press member and the first and
second seal means to a source o pressurized fluid. The
source of pressurized fluid is preferably pressurized air,
_5_
' I
B61 ~31 651 ~ 1
such that during use of the appar~tus with the seal means
disposed in the inflated first position thereof, the
pressurized air within the compartment is above arnbient
atmospheric pressure.
Preferably, the pressurized air within the compart-
ment is within the range 1-2 pounds per square inch and
the seal means are each internally pressurized within the
range 20-40 pounds per square inch in the first position
thereof.
The present invention also includes a method of
sealing a blanket extending through an extended nip so
that the blanket is sealed relative to the first press
member. The method includes the steps of deflating the
seals, moving the blanket axially relative to, and around,
the first press mernber so that the blanket encircles and
enwraps the first press member, then inflating the seals
so that the seals are urged radially outwards against the
inner surface of the blanket for maintaining a seal
between the blanket and the stationary first press member
when the blanket rotates relative to, and around, the
stationary first press member.
Although the present invention, as described herein-
after, is described particularly with regard to one manner
of carrying out the invention, it will be evident to those
! skilled in the art that there are many variations of the
present inventive concept and that these numerous
variations and modifications fall within the spirit and
i scope of the present invention as defined by the appended
claims and that the invention is not limited to the
particular embodiment to be described herei~after.
i BRIEF DESCRIPTION OF TI~E DRAWINGS
~ .... .. .. ~
Figure 1 is a side-elevational view Oe an extended
nip press of the "apple" type showing a stal,ionary ~apple" ¦
shaped first press member and a cooperatillg rotatable
I
B61~l~514
~ 3~ 7 ~ ~
second press member with an inflata~le sealing apparatus
disposed between the blanket and the first press member.
Fiyure 2 is a sectional view taken on the line 2-2 of
figure 1.
Figure 3 is an enlarged fragmentary view of the seal
means showing the disposition of the first and second
seals relative to the blanket and the first and second
heads when the seals are inflated.
Figure 4 shows one of the seals in the deflated
second position thereof.
Figure 5 is an enlarged sectional view of one of the
seals in an air inflated third position thereof, the seal
being subjected to radial deflection by the blanket.
Figure 6 shows the seal of figure 5 in an inflated
third position thereof wlth the blanket having been moved
axially relative to the first press member while maintain-
ing a sealing relationship between the blanket and the
first press member;
Figure 7 is a sectional view of an embodiment of the
present invention showing one of the seal means with the
base portlon thereof defining a convex surface.
Figure 8 is a sectional view of another alternative
embodiment of the present invention showing one of the
seal means v1ewed in a cross-machine direction and showing
an alternative means of anchoring the seal means to the
rotatable head.
Figure 9 is a sectional view of the seal means shown
in figure 3 in the inflated first disposition thereof.
Figure lO is a sectionaI view of the seal means shown
in figure 9 but with the seal means in the second deflated
disposition thereof.
Figure ll is a sectional view o the seal means shown
in figure 9 with the seal means disposed in the compressed
third disposition thereof.
~61~16514
-` ~L3~'7::1LS6
Figure 12 is a sectional vie~of a further embodiment
of the present invention showing an alternative seal means
in which the sealing portion defines a plain surface; and
Figure 13 is a fragmentary sectional view of the seal
means showing the compartment and the rneans for connecting
the compartment to a source of pressurized air.
Similar reference numerals refer to similar elements
throughout the detailed description o~ the various embodi-
ments of the present invention.
DETAILED DESCRIPTION OF THE DRAWINGS
Figure 1 is a side-elevational view of a typical
"apple" type extended nip press having a sealing apparatus
according to the present invention. The apple type
extended nip press is generally designated 10 and includes
a first stationary apple-shaped press member 12 and a
cooperating rotatable second press member 14 . The first
and second press members 12 and 14 respectively, define
therebetween, an extended nip 16 for the passage
therethrough of a paper web W to be pressed. A felt F
simultaneously passes thr~ough the extended nip 16 such
that as water is removed from the web W such water is
taken up by and absorbed by the felt F. A blanket 18
extends~through the nip 16 with the blanket 18 being
disposed between the felt F and the first press member 12.
The first member 12 def1nes a ~concave surface 20 for the
cooperating reception therein of the rotatable second
press member 14. During operation of the extended nip
press 10 the blanket 18 moves substantially at the same
:.
speed as the felt F and web W during passage throùgh the
extended nip 16 so that there exists relative movement
" between the inner surface 22 of the blanket 18 and the
concave surface 20 of the first stationary press member
12. This relative movément of the blanket 18 relative to
-8-
.. I
B~181651~ I
~3~7~S6
~he first press memb~r 12 necessit~ates the provision of alubricatiny medium between the inner surface 22 of the
blanket 18 and the concave surface 20 of the first press
member 12.
~ ith the prior art proposals, the provision of a
lubricating medium such as oil, has resulted in the
seepage of such oil laterally relative to the machine
direction as indicated by the double-headed arrow 24 as
shown in figure 2. When sùch oil seepage occurs, an oil
film may reach the respective edges 26 and 28 of the
blanket 18 as indicated in fi.gure 2 and due to the rota-
tiOIl of the blanket 18 around the stationary first press
member 12 particles of contaminating oil have been thrown
outwardly and have sometimes caused contamination of the
surface of the paper web ~. ¦
As shown in figure 2, the present invention includes
a first rotatable head 30 disposed adjacent to the first
end 32 of the first press member 12. The first head 30 is
disposed coaxial relative to the first press member 12.
Furthermore, a second rotatable head 34 is disposed
adjacent to the second end 36 of the first press member 12
so that the second head 34 is disposed coaxial relative to
the first head 30 and the first press member 12. A first
annular seal means 38 is disposed between the blanket 18
and the first head 30 for sealing the blanket 18 relative
to the first head 30. Also, a second annular seal means
40 is disposed between the blanket 18 and the second head
34 for sealing the blanket 18 relative to the second head
34 such that when the first and second seal means 38 and
40 respectively are in an inflated first position thereof
as shown in figure 2, the blanket 18 is permitted to
rotate coaxially around the first press member 12.
However, when the first and second seal means 38 and 40
respectively are disposed in a deflated second position
_g_
`. I
~3v~ ; B61816514
thereof, the blanket 18 is movable~axially relative to the
seal means 38 and 40 for replacing the blanket 18.
- More particularly, figure 2 shows the first and
second rotatable heads 30 and 34 respectively as each
I defining a disc-shaped configuration with the first and
second heads 30 and 34 respectively, each being rotatable
relative to the stationary first press member 12.
Figure 3 is an enlarged fragmentary sectional view of
the first and second seal means 38 and 40 respectively.
The seals means 38 and 40 are of an elastomeric material
. and are preferably fabricated from rubber. Each of the
seal means 38 and 40 are of hollow, toroidal configuration
as shown in figure 3. The first and second seal means 38
and 40 are able to be inflated or deflated by means of a
flow control means generally designated 42 which is
connected respectively to the first and second seal means
38 and 40 for controlling the inflation and deflation of
the annular seal means 38 and 40.
AS shown in figure 3, the first annular sealing means
38 includes a base portion 44 for connecting the seal
means 38 to the rotatable head 30 A sealing member 46 is
disposed diametrically opposite to the base portion 44
such that when the sealing means 38 is inflated, the
sealing member 46 is urged into sealing conformity with
the inner surface 22 of the movable blanket 18. As shown
in figure 3, the sealing member 46 defines a serrated
surface 48 with the serrations extending in a machine
direction such that as the sea~ing member 38 is urged
against the inner surface 22, an effective seal is estab-
li.shed thereby.
Similarly, the second sealing means 40 also includes
a base portion 50 and a sealing member 52 with a corre~
spondingly serrated surface 54 defined thereby,
-10-
B61816514
~IIL3~r~ ~l,S~;
In a specific embodirnent of t~he invention, the seals
38 and 40 expand radially by a distance of two inches
(5.08 centimeters) between the first and third positions
o~ the seals. The third position is attained during
passage of the inflated seal through the nip 16. In
effect, this means that if the serrated surface 48 of the
sealing member 46 defines a circle having a diameter of
ifty-six inches (142.24 centimeters) when compressed,
this serrated surface 48 will define a circle having a
diameter of sixty inches (152.4 centimeters) when in the
inflated first position thereof. Such movement of the
serrated surfaces 48 and 54 between the first and third
inflated positions thereof maintains sealing conformity
with the blanket. When the seals 38 and 40 are deflated to
the second position thereof as shown particularly in
I
figure 10, the clearance between the sealing members 46
and 52 and the blanket 18 i~s ample for allowing lateral
removal of the blanket. When the seals 38 and 40 are
inflated, the serrated surfaces 48 and 54 move radially
outwardly sufficient to establlsh an effective seal
relative to the inner surface 22 of the blanket 18 for
inhibiting any cross-machine directional seepage of
lubricating oil that would otherwise cause contamination
of the treated paper web.
Figure 7 is a sectional view showing an alternative
embodiment of the present invention. Similar reference
numerals are used throughout the detailed description to
indicate similar elements of the various embodiments of
the present invention however, such numerals include
alphabetical suffixes added thereto.
In figure 7, the sealing means 38a includes a sealing
member 46a and a base portion ~4a. However, the base
portion 44a defines a convex surface 45 which cooperates
with a concave surface 47 defined by the first rotatable
~3~7~5~ B6~ sl4
head 30a. This arranyement facilriates mounting of the
seal means 38a onto the head 30a.
Fiyure 8 shows an alternative embodiment of the
present invention in which a rim portion 49 of the first
rotatable head 30b defines a plurality of radial slots
51,53 and 55. A plurality of threaded fasteners 57,58 and
59 are anchored within the base portion 44b such that
inwardly extending threaded portions 60,61 and 62 cooper-
ate with the radial slots 51,53 and 55 respectively so
that when the seal means 38b is moved axially relative to
the rim portion 49 the threaded portions 60-62 are re-
ceived within the radial slots 51,53 and 55 respectively.
A plurality of internally-threaded members 63,64 and 65
cooperate with the threaded portions 60-62 for anchoring
the base portion 44b relative to the rim portion 49.
As shown in figures 9 to 11, the sealing member 38 is
movable between a first, second and third position thereof
as shown in figure 9-11 respectively. This third, com-
pressed position, as shown in figure 11 is attained during
compression of the seal means 38 when the inflated seal
means 38 passes through the extended nip 16.
Preferably, when manufacturing the seal means 38, 38a
or 38b, the seal means defines, in an unstressed and
unbiased disposition thereof, a cross-sectional configura-
tion substantially equlvalent to the cross-sectional
configuratlon of the seal means when disposed in the
second position thereof, as shown in figure 10. This
unstressed and unbiased disposi~ion of the seal means is
disposed between the first and third positions as shown in
figures 9~and 11 respectively so that during stressing of
the seal means during use of the sealing apparatus
between the first and third positions as shown in figures
9 and 11, the life of the seal means is extended.
-12-
.'
~3~5~ e61816514
In,an alternative embodirnent ~ the present inventionas shown in figure 12, in addition to the base portion 44c
for connecting the respective seal means 38c to the
respective rotatable head 30c, a sealing portion 66 is
provided with the sealing portion 66 being disposed
diametrically opposite to the base portion 44c. The
sealing portion 66 defines a sealing surface 68 which is
disposed adjacent to the inner surface 22c of the movable
blanket 18c. The sealing surface 68 is a plain surface.
In yet another embodiment of the present invention,
as shown in figure 13, channel means 70 defined by the
stationary first press member 12d connect-a compartment 72
defined between the blanket 18d , the first press member
12d and the first and second seal means 38d and 40d to a
source of pressurized fluid 74 such that during use of the
apparatus, with the seal means 38d and 40d disposed in the
inflated first or third disposition thereof, the pressure
within the compartment 72 is above ambient atmospheric
pressure. Preferably, the pressurized fluid is air and
the pressure within the compartment 72 is within the range
1-2 pounds per square inch and the pressure within the
seal means 38d and 40d is 20-40 pounds per square inch
when the seal means 38d and 40d are in the first or third
position thereof.
In operation of the apparatus according to the
present invention, the flow control means 42 is operated
in order to deflate the seals 38 and 40 so that the
blanket 18 can be moved axially to encircle and enwrap the
first press member 12. When the blanket 18 has been
correctly aligned over and around the first press member
12 with the annular seals 38 and 40 adjacent to the
respective edges 26 and 28 of the blanket 18, the flow
control means 42 is operated to inflate the seals 38 and
40 such that the serrated surfaces 48 and 54 thereof move
-13-
i
B61~1651~
~3~'7~S~;
radially outwards into sealing en~agement with the innersurface 22 of the blanket 18 so that the blanket 18, seals
38 and 40 and heads 30 and 3~ can, together, rotate around
tne stationary first press member 12. Furthermore, when
the blanket passes the concave surface 20 of the ~apple"
shaped first press member 12, the seals 38 and 40 can
compress and deform in conformity with the configuration
of the extended nip while maintaining the required sealing
relationship between the blanket 18 and first press member
12.
As shown in figure 4, when the blanket 18 is to be
removed, the seals 38 and 40 are deflated. Figure 4
merely shows seal means 38 in the deflated position. With
the seal means 38 deflated, a clearance of approximately
one inch (2.54 centimeters) i9 provided between the inner
surface 22 of the blanket 18 and the sealing means 38 and
this is ample to permit the sideways removal of the
blanket 18.
Figure 5 shows the seal 38 in an inflated position
thereof with the seal 38 being subjected to radial de-
flection by the blanket 18. Also any lateral deviation of
the blanket 18 relative to the stationary first press
member 12 when the seal 38 is inflated can be adequately
accommodated by the sealing relationship established
between the serrated surface 48 and the inner surface 22
of the blanket 18 as particularly shown in figure 6.
Those skilled in the art will appreciate that the
radius of èach of the heads 30 to 34 is slightly less than
; the dlstance between the axis of the first press member 12
and the lowest point of the concave surface 20.
The present invention provides a simple and low cost
means for overcoming the problem of web contamination by
oil sprayed from the press blanket.
-14-
