U.S. patent application number 10/921724 was filed with the patent office on 2005-01-27 for smoothing device.
Invention is credited to Esslinger, Klaus, Henssler, Joachim, Meschenmoser, Andreas, Steiner, Karl.
Application Number | 20050016703 10/921724 |
Document ID | / |
Family ID | 27740289 |
Filed Date | 2005-01-27 |
United States Patent
Application |
20050016703 |
Kind Code |
A1 |
Steiner, Karl ; et
al. |
January 27, 2005 |
Smoothing device
Abstract
A smoothing device of a press arrangement for dewatering a
fibrous web in a machine for producing or finishing the fibrous web
including a rough belt, a smooth belt and a smoothing element. The
rough belt being endless and water-absorbing. The rough belt
arranged on a side of the fibrous web. The smooth belt is endless
and arranged on an opposite side of the fibrous web. The rough
belt, the fibrous web and the smooth belt running through a press
nip together and the rough belt is led away from the fibrous web
after passing through the press nip. The smoothing element forms a
smoothing nip with the smooth belt after the rough belt is led away
from the fibrous web, the smoothing element having a smooth
pressing surface.
Inventors: |
Steiner, Karl; (Tubingen,
DE) ; Meschenmoser, Andreas; (Horgenzell, DE)
; Henssler, Joachim; (Ravensburg, DE) ; Esslinger,
Klaus; (Nattheim, DE) |
Correspondence
Address: |
Todd T. Taylor
Taylor & Aust, P.C.
142 S. Main Street
P.O. Box 560
Avilla
IN
46710
US
|
Family ID: |
27740289 |
Appl. No.: |
10/921724 |
Filed: |
August 19, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10921724 |
Aug 19, 2004 |
|
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|
PCT/EP03/01315 |
Feb 11, 2003 |
|
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Current U.S.
Class: |
162/193 ;
162/358.1; 162/359.1; 162/363; 34/117 |
Current CPC
Class: |
D21F 3/045 20130101;
D21F 3/04 20130101 |
Class at
Publication: |
162/193 ;
162/358.1; 162/359.1; 162/363; 034/117 |
International
Class: |
D21F 003/02; D21F
003/04 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 22, 2002 |
DE |
102 07 375.9 |
Claims
What is claimed is:
1. A smoothing device of a press arrangement for dewatering a
fibrous web in a machine for one of producing and finishing the
fibrous web, comprising: a rough belt being endless and
water-absorbing, said rough belt arranged on a side of the fibrous
web; a smooth belt being endless and arranged on an opposite side
of the fibrous web, said rough belt, the fibrous web and said
smooth belt running through a press nip together, said rough belt
being led away from the fibrous web after passing through said
press nip; and a smoothing element forming a smoothing nip with
said smooth belt after said rough belt is led away from the fibrous
web, said smoothing element having a smooth pressing surface.
2. The smoothing device of claim 1, wherein said smooth belt
transfers the fibrous web to said smoothing element.
3. The smoothing device of claim 1, wherein at least one of said
smoothing element and said smooth belt are arranged so that they
move from each other.
4. The smoothing device of claim 1, wherein said smooth belt has a
first softness and said smoothing element has a second softness,
said first softness greater than said second softness.
5. The smoothing device of claim 1, wherein said smooth belt and
said smoothing element are pressed with a contact force of between
approximately 3 kN/m and 100 kN/m.
6. The smoothing device of claim 5, wherein said contact force is
between approximately 5 kN/m and 20 kN/m.
7. The smoothing device of claim 1, wherein said smooth belt and
said smoothing element are pressed with a contact force which is
one of set and controlled as a function of a level of two-sidedness
of the fibrous web after the smoothing device.
8. The smoothing device of claim 1, wherein said smooth belt and
said smoothing element are pressed with a contact force which is
one of set and controlled as a function of a level of two-sidedness
of the fibrous web after the machine.
9. The smoothing device of claim 1, wherein said smoothing element
is a smoothing belt that is endless and circulating.
10. The smoothing device of claim 1, wherein said smoothing element
is a smooth, rotatable smoothing roll.
11. The smoothing device of claim 10, wherein said smoothing roll
is heated.
12. The smoothing device of claim 1, wherein said press nip is the
last press nip of a plurality of press nips of the machine.
13. The smoothing device of claim 1, further comprising a drying
group for drying the fibrous web, the fibrous web being transferred
from said smoothing element to said drying group in a transfer
region.
14. The smoothing device of claim 13, further comprising at least
one suction device, the fibrous web being transferred in said
transfer region with the assistance of said at least one suction
device.
15. The smoothing device of claim 13, wherein said drying group
further includes: a drying fabric supporting the fibrous web; a
plurality of drying cylinders; a plurality of guide rolls, said
drying fabric supporting the fibrous web being alternately guided
over one of said plurality of drying cylinders and one of said
plurality of guide rolls.
16. The smoothing device of claim 15, wherein said plurality of
drying cylinders are arranged under the fibrous web.
17. The smoothing device of claim 1, wherein said smooth belt runs
above the fibrous web.
18. The smoothing device of claim 15, further comprising a suction
device, the fibrous web being transferred to said drying fabric
from said smoothing element in said transfer region, said suction
device being proximate to said drying fabric in said transfer
region.
19. The smoothing device of claim 18, wherein said suction device
is a suction box.
20. The smoothing device of claim 15, wherein said smooth belt runs
under the fibrous web.
21. The smoothing device of claim 20, further comprising a transfer
suction roll, the fibrous web being transferred from said smoothing
element to said transfer suction roll, the fibrous web then being
transferred from said transfer suction roll to said drying
fabric.
22. The smoothing device of claim 20, further comprising: a suction
device; and an air permeable transfer belt wrapping around said
suction device, the fibrous web being transferred from said
smoothing element to said air permeable transfer belt, said air
permeable transfer belt then transferring the fibrous web to said
drying fabric.
23. The smoothing device of claim 22, wherein said suction device
is a suction roll.
24. The smoothing device of claim 1, further comprising a suction
device for attracting the fibrous web by suction, said suction
device being arranged downstream of said smoothing element in a
running direction of the fibrous web.
25. The smoothing device of claim 24, wherein said suction device
includes at least one of a suction box and a suction roll.
26. The smoothing device of claim 25, wherein said suction box is
arranged directly on an unwrapped region of a circumferential
surface of said suction roll.
27. The smoothing device of claim 25, wherein said suction box
includes a first element and a second element each of which are
pressed resiliently against the fibrous web with a contact force, a
zone between said first element and said second element being a
suction zone for attracting the fibrous web by suction.
28. The smoothing device of claim 27, wherein said contact force of
at least one of said first element and said second element is set
to a predetermined value.
29. The smoothing device of claim 24, further comprising a transfer
belt, the fibrous web being transferred from said smoothing element
to said transfer belt.
30. The smoothing device of claim 24, further comprising a drying
fabric, the fibrous web being transferred from said smoothing
element to said drying fabric.
31. The smoothing device of claim 24, further comprising: at least
one further suction device; and a drying cylinder, the fibrous web
after being transported past said suction device is conveyed over
said drying cylinder and said at least one further suction
device.
32. The smoothing device of claim 25, wherein the fibrous web
includes a threading strip associated with the fibrous web, at
least one of said suction roll and said suction box including a
region being separately evacuateable, said region corresponding to
a width of said threading strip during the threading of the fibrous
web.
33. The smoothing device of claim 25, wherein at least one of said
suction roll and said suction box is one of set on and off said
smoothing element.
34. A method of threading a strip of a fibrous web in a papermaking
machine, comprising the step of applying a vacuum to the strip in a
region proximate to one of a suction roll and a suction box.
35. The method of claim 34, further comprising the step of
completing a threading operation, said completing a threading
operation including the steps of: bringing the strip to a full
width of the fibrous web by way of a couching device; and
contacting a drying fabric with a smoothing roll.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation of PCT application No.
PCT/EP03/01315, entitled "SMOOTHING DEVICE", filed Feb. 11,
2003.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a smoothing device for a
press arrangement for dewatering a paper, board, tissue or other
fibrous web in a machine for producing and/or finishing the
same.
[0004] 2. Description of the Related Art
[0005] Press arrangements lead to pronounced two-sidedness of the
fibrous web with regard to smoothness, since the smooth belt
smoothes the fibrous web while the other belt, because of the
necessary porosity in order to ensure the water absorption
capability, has a certain surface roughness and therefore roughens
the fibrous web. However, the smooth belt provides advantages in
guiding the fibrous web, so that omitting the latter would not be
desired.
[0006] What is needed in the art is, an apparatus to reduce the
two-sidedness of the fibrous web in the simplest possible way.
SUMMARY OF THE INVENTION
[0007] According to the present invention, a smooth belt forms a
smoothing nip with a smoothing element having a smooth pressing
surface after the rough belt is led away. This smoothing nip
increases the smoothness on both sides of the fibrous web while
reducing the two-sidedness with minimum expenditure. The smoothing
element simultaneously guides the fibrous web after the smoothing
nip, that is to say that the smoothing belt transfers the fibrous
web to the smoothing element.
[0008] In order to assist the transfer of the fibrous web, the
surface of the smooth belt is softer than that of the smoothing
element.
[0009] In order to make it possible to discharge broke into the
machine basement, it is advantageous if the smoothing element
and/or the smooth belt are arranged such that they can be moved
away from each other and, as a result, a discharge gap is
implemented.
[0010] Since the fibrous web is still relatively moist in the
region of the press arrangement, it is sufficient, for the purpose
of smoothing, if the smooth belt and the smoothing element are
pressed against each other with a contact force which is between 3
kN/m and 100 kN/m, preferably between 5 kN/m and 20 kN/m. For the
purpose of optimization, in the interests of the lowest possible
two-sidedness of the fibrous web, it is advantageous if the smooth
belt and the smoothing element are pressed against each other with
a contact force which is set or controlled as a function of the
level of two-sidedness of the fibrous web after the smoothing
device, preferably at the end of the machine.
[0011] In this case, the smoothing element is formed as a smooth,
endlessly circulating smoothing belt or else as a smooth, rotatable
smoothing roll. In the case of the smoothing roll, for the purpose
of drying and for the purpose of increasing the smoothness of the
rough side of the fibrous web, it is advantageous if the smoothing
roll is heated and, in particular, is formed as a drying
cylinder.
[0012] Because of the low accumulation of water in the press nip,
smooth belts are preferably used at the end of the press section.
This means that the press nip should preferably be the last press
nip of the machine.
[0013] In order to improve the guidance of the fibrous web,
particularly at high speeds, in particular if the fibrous web is
transferred from the smoothing element to a drying group for drying
the fibrous web, the transfer should be assisted by at least one
suction device. However, it can also be advantageous if the fibrous
web runs from the smoothing element to a following element with a
short free draw, that is to say a short unsupported distance. In
the drying group, the fibrous web is supported by a drying fabric,
and is led alternately over heated drying cylinders and guide
rolls. The drying cylinders are arranged under the fibrous web in
order to improve the web guidance, to simplify the construction and
to permit simple discharge of broke.
[0014] If the smooth belt runs above the fibrous web, then the
fibrous web can be transferred in a secure and simple way from the
smoothing element to a drying fabric of a following drying group.
The drying fabric is led past a suction device, preferably in the
form of a suction box, in the transfer region. However, somewhat
better web guidance results if the smooth belt runs under the
fibrous web. In this case, the fibrous web is simply transferred
from the smoothing element to a transfer suction roll. The suction
roll then, in turn, transfers the fibrous web to the drying fabric
of the drying group. However, it is also possible for the fibrous
web to be transferred from the smoothing element to an
air-permeable transfer belt which, in the transfer region, wraps
around a suction device. The suction device being in the form of a
suction roll, and it transfers the fibrous web to the drying fabric
of the following drying group.
[0015] In a development of the invention, provision is made for a
suction device for attracting the fibrous web by suction that is
arranged downstream of the smoothing element in the running
direction of the fibrous web. In this case, the arrangement of the
suction device is independent of the conveying mechanism onto which
the fibrous web is transferred. Thus, the fibrous web can be
transferred, for example, onto a transfer belt or directly onto a
drying fabric. By way of the suction device, the fibrous web is
detached from the preceding smoothing element, in particular a
smoothing roll, under a defined suction force. Web flutter and
breaks, such as can occur in the case of an open draw without
support by a suction device, are thereby avoided. The suction
device is preferably configured in such a way that it includes a
suction box and/or a suction roll. The suction roll is preferably
equipped on its circumferential surface with a helical or spiral
groove, in which holes for extracting air and water are made at
fixed intervals. For this purpose the perforated roll shell is
connected to a vacuum source. The suction box is preferably
configured in such a way that it immediately adjoins an unwrapped
region of the circumferential surface of the suction roll. In a
particular refinement, the suction box has a first and a second
element that is pressed resiliently against the fibrous web,
between which, at least one suction zone, for attracting the
fibrous web by suction, is formed. In one embodiment of the present
invention, provision is made for a plurality of zones to be
evacuated with different pressures to be arranged after and/or
beside one another in the region of the suction box. In this manner
the desired suction pressure can be set very precisely and in
accordance with the web speed and other web parameters. Here, it
also proves to be advantageous if the contact pressure of at least
one of the two elements can be set.
[0016] In another embodiment of the present invention, provision is
made for it to be possible for the fibrous web, after being
transported past the suction device, to be conveyed over a drying
cylinder and at least one further suction device.
[0017] The present invention is also suitable for use when
threading a strip of a fibrous web. For this purpose, it is
sufficient, for example, if the suction roll is evacuated only in a
section over which the threading strip is guided. In this case, if
a suction box is also present, the latter does not necessarily have
to be evacuated. However, the suction box can also be evacuated in
accordance with the width of the evacuated section of the suction
roll. Using this method for threading the start of a fibrous web,
it is possible to lead the web on without a rope. The strip can be
expanded to the full width of the fibrous web with the aid of a
couching device, the suction roll and/or the suction box then being
evacuated over the full width of the fibrous web.
[0018] The drying fabric is brought into contact with the smoothing
roll. For this purpose, the suction roll and the suction box are
arranged such that it can be pivoted.
[0019] In a further embodiment of the present invention, the drying
fabric is driven at a somewhat higher speed than the belt of the
press section. In this way, the fibrous web can be detached more
easily from the smoothing element, in particular the smoothing
roll. In addition, the technological paper properties of the web,
in the web running direction, are influenced positively as a
result. A speed difference of between 0.5% and 5.0% is
preferred.
[0020] With the present invention, closed web guidance from the wet
end as far as the drying section is implemented and web flutter and
web breaks of the fibrous web are avoided. The press arrangement
ensures low two-sidedness of the web with respect to the smoothness
with a simultaneously very high level of smoothness and reliable
web threading. This is based on the fact that the fibrous web has
no, or only a short, free draw region, that is to say a region in
which it is not supported.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The above-mentioned and other features and advantages of
this invention, and the manner of attaining them, will become more
apparent and the invention will be better understood by reference
to the following description of embodiments of the invention taken
in conjunction with the accompanying drawings, wherein:
[0022] FIG. 1 shows a schematic side view of a press arrangement
with a smoothing device of an embodiment of the present
invention;
[0023] FIG. 2 shows a press arrangement with another embodiment of
a smoothing device;
[0024] FIG. 3 shows a schematic side view of another embodiment of
a press arrangement with a smoothing device;
[0025] FIG. 4 shows a further schematic view of another embodiment
of a press arrangement with a smoothing device; and
[0026] FIG. 5 shows a suction roll in conjunction with a suction
box in an enlarged illustration of the present invention.
[0027] Corresponding reference characters indicate corresponding
parts throughout the several views. The exemplifications set out
herein illustrate one preferred embodiment of the invention, in one
form, and such exemplifications are not to be construed as limiting
the scope of the invention in any manner.
DETAILED DESCRIPTION OF THE INVENTION
[0028] In every case, fibrous webs 1, 20 and 53 are led through a
press nip together with an endlessly circulating, water-absorbing,
relatively rough belt 2 or 24 in the form of a press felt and a
likewise endlessly circulating, smooth belt 3 and 25 arranged on
the opposite side of fibrous webs 1, 20 or 53. In at least one
case, the press nip is the last or even the only press nip of a
press section of a papermaking machine for dewatering fibrous web
1, 20 and 53 and is generally formed by two press rolls 12 or 31
and 32 pressed against each other. In the press nip, only
relatively little water is pressed out of fibrous web 1, 20 or 53,
so that only one press felt is sufficient to pick up the water
pressed therefrom. Smooth belt 3 or 25 improves the guidance of
fibrous web 1, 20 or 53, in particular at high machine speeds. The
two belts 2 and 3 or 24 and 25 are respectively led over guide
rolls 9 or 26 outside the press nip.
[0029] From the press section, fibrous web 1, 20 or 53 is led to a
drying group of the papermaking machine. There, fibrous web 1, 20
and 53 is supported by a drying fabric 5 or 38, and is led
alternately over heated drying cylinders 10, 41 and 51 and
evacuated guide rolls 11 and 42. Drying cylinders 10, 41 and 51 are
arranged under and guide rolls 11 and 42 are arranged above fibrous
web 1, 20 or 53. The meandering run of fibrous web 1, 20 or 53
results in a simple and space-saving construction of the drying
group. In addition, drying groups of this type are highly suitable
for high machine speeds and have fast and reliable discharge of
broke.
[0030] In the press nip fibrous web 1, 20 and 53 is smoothed on one
side as a result of the contact with smooth belt 3 or 25, while the
other side remains rough or even becomes rougher as a result of the
contact with the relatively rough press felt. Although this
two-sidedness can be reduced in the calendaring units, arranged at
the end of the machine, it can seldom be entirely corrected.
[0031] After the press nip, however, fibrous web 1, 20 and 53 is
still relatively moist, so that the two-sidedness can be influenced
with relatively simple means and low pressing forces. For this
purpose, the press felt is led away from fibrous web 1, 20 and 53
after the press nip. Fibrous web 1, 20 or 53 can then run through a
smoothing device, in which the two-sidedness of the fibrous web 1,
20 and 53 is counteracted by smoothing. There then follows the
transfer of fibrous web 1, 20 or 53 to a respective drying fabric 5
or 38 of the following drying group.
[0032] The smoothing device is formed by a smoothing roll 4, 34 or
50, which is pressed against smooth belt 3, 25 with fibrous web 1,
20 or 53 therebetween. In this case, smooth belts 3 and 25 are
respectively, supported by a press roll 13 and 35 on the opposite
side of the fibrous web. The position of smoothing roll 4, 34 or 50
can be changed in such a way that the smoothing nip can also be
opened in order to discharge broke. Of course, it is also possible
to arrange press roll 13 or 35 to be displaceable. Furthermore,
smoothing roll 4, 34 or 50 can also be replaced by a smoothing
belt, which is forced toward smooth belt 3 or 25 by a roll or
likewise wraps around press roll 13 or 35 with smooth belt 3 or
25.
[0033] In the press arrangements that are illustrated in FIGS. 1
and 2, smooth belt 3 runs under fibrous web 1, which offers
advantages in the guidance of the web.
[0034] In FIG. 1, following the smoothing operation, fibrous web 1
is transferred from smoothing roll 4 to a transfer belt 14, which,
in turn, passes on fibrous web 1 to drying fabric 5. Transfer belt
14 is associated with two transfer points, transfer belt 14,
wrapping around a roll 8. The roll associated with smoothing roll 4
is designed as a suction roll 7 in order to assist the
transfer.
[0035] According to FIG. 2, fibrous web 1 is transferred to
transfer suction roll 7 then to drying fabric 5. In contrast to
this, smooth belt 3 in the press arrangement shown in FIG. 3 is
arranged above fibrous web 1. This simplifies the transfer of
fibrous web 1 after smoothing, since fibrous web 1 can be
transferred from smoothing roll 4 to drying fabric 5 directly, that
is to say without being turned. In order to assist the transfer,
drying fabric 5 runs on a suction box 6 in the region of the
transfer. The vacuum originating from suction box 6 pulls fibrous
web 1 toward drying fabric 5.
[0036] A fibrous web 20 as illustrated in FIG. 4 is transported in
the direction of an arrow A by transport belts 21-25, each of which
run over guide rolls 26. At the transfer points between transport
belts 21-25 there are suction rolls with stationary suction boxes
and a roll shell that rotates therearound, such as suction rolls 27
and 28 with suction boxes 29 and 30, respectively.
[0037] Between press rolls 31 and 32, of which the lower is
equipped with a pressing element 33, fibrous web 20 is led to a
pair of smoothing rolls 34 and 35. Smoothing roll 34 is
additionally equipped with doctors 36 and 37 for removing
contaminants.
[0038] From transport belt 25, fibrous web 20 is transferred onto
drying fabric 38. For this purpose, use is made of suction roll 39
in conjunction with suction box 40, which is illustrated above
suction roll 39 and, in one embodiment, has an approximately
trapezoidal cross section. As a result of the arrangement of
suction box 40 and of suction roll 39, fibrous web 20 is
transferred without a free draw directly from contact with
smoothing roll 34 onto a suction region on the side facing suction
roll 34. Drying fabric 38 is rotated at a speed of 0.5 to 5.0%
faster than transport belts 21-25.
[0039] Fibrous web 20 is then led onward over drying cylinder 41
and from there to a further combination of suction roll 42 and
suction box 43.
[0040] FIG. 5 shows a suction box 52 arranged between a smoothing
roll 50 and a drying cylinder 51 or between two drying cylinders 50
and 51 in order to attract, by suction, fibrous web 53 (shown on
only one side here for reasons of simplification) from smoothing
roll 50 and to transfer it to drying cylinder 51. Fibrous web 20 is
led around suction roll 54 underneath suction box 52. In order to
attract fibrous web 20 by suction, suction box 52 is equipped with
a suction region 57 bounded by springy elements 55 and 56 and
having an outlet 58 for the discharge of extracted air and
moisture. Elements 55 and 56 can be actuated by adjusting shafts 59
and 60 respectively in order to change their contact pressure
against fibrous web 53. Suction region 57 can be followed by
further suction regions, which, just like suction region 57, are
bounded by resilient elements. It is possible for the suction force
to be changed individually in each of the suction regions in order
to achieve optimum transfer of fibrous web 53 to drying cylinder
51.
[0041] While this invention has been described as having a
preferred design, the present invention can be further modified
within the spirit and scope of this disclosure. This application is
therefore intended to cover any variations, uses, or adaptations of
the invention using its general principles. Further, this
application is intended to cover such departures from the present
disclosure as come within known or customary practice in the art to
which this invention pertains and which fall within the limits of
the appended claims.
* * * * *