U.S. patent application number 16/572819 was filed with the patent office on 2020-03-19 for machine and method for the production of a fibrous web.
This patent application is currently assigned to Voith Patent GmbH. The applicant listed for this patent is Voith Patent GmbH. Invention is credited to Jonas Bergstrom, Caio Penteado.
Application Number | 20200087857 16/572819 |
Document ID | / |
Family ID | 67220701 |
Filed Date | 2020-03-19 |
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United States Patent
Application |
20200087857 |
Kind Code |
A1 |
Penteado; Caio ; et
al. |
March 19, 2020 |
MACHINE AND METHOD FOR THE PRODUCTION OF A FIBROUS WEB
Abstract
A machine for the production of a fibrous web, with a forming
region, including a forming roll and a permeable inner belt which
at least partially wraps around the forming roll together with an
outer belt for formation of the fibrous web. A press device is
immediately downstream from the forming region for additional
dewatering of the fibrous web in a press nip and with a downstream
drying cylinder. The fibrous web is carried supported on the inner
belt from the forming region until the transfer to the heated
surface of drying cylinder takes place. The inner belt is textured
in order to provide texture to fibrous web and the transfer roll is
a shoe roll in order to provide an extended transfer nip.
Inventors: |
Penteado; Caio; (Sao Paulo,
BR) ; Bergstrom; Jonas; (Ulm, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Voith Patent GmbH |
Heidenheim |
|
DE |
|
|
Assignee: |
Voith Patent GmbH
Heidenheim
DE
|
Family ID: |
67220701 |
Appl. No.: |
16/572819 |
Filed: |
September 17, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D21F 3/10 20130101; D21F
11/006 20130101; D21F 3/08 20130101; D21F 11/14 20130101; D21F
7/008 20130101; D21H 27/002 20130101; D21F 9/02 20130101; D21F
3/0227 20130101; D21F 3/045 20130101; D21F 3/029 20130101; D21F
5/181 20130101 |
International
Class: |
D21F 9/02 20060101
D21F009/02; D21F 3/04 20060101 D21F003/04; D21F 3/08 20060101
D21F003/08; D21F 3/02 20060101 D21F003/02; D21F 11/14 20060101
D21F011/14; D21F 11/00 20060101 D21F011/00; D21F 3/10 20060101
D21F003/10; D21F 7/00 20060101 D21F007/00; D21H 27/00 20060101
D21H027/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 17, 2018 |
DE |
102018122632.2 |
Claims
1. A machine for the production of a fibrous web, in particular a
tissue web, with a forming region, the machine comprising: a
forming roll; an outer belt; a permeable inner belt which at least
partially wraps around said forming roll together with said outer
belt for formation of the fibrous web in a forming region; and a
press device immediately downstream from the forming region, the
press device including: a press roll; a lower press belt; a
transfer roll; a mating roll along with said press roll forming a
press nip for additional dewatering of the fibrous web, wherein the
press nip is the first press nip of said press device, wherein the
fibrous web is carried through said press nip supported between
said inner belt and said lower press belt; and a drying cylinder
being downstream from said press device, wherein the fibrous web is
carried supported on said inner belt in an extended transfer nip
which is formed between said transfer roll and said drying cylinder
from the forming region until the transfer from said inner belt to
a heated surface of the drying cylinder, wherein said inner belt is
textured providing texture to the fibrous web and said transfer
roll is a shoe roll providing the extended transfer nip.
2. The machine of claim 1, wherein said lower press belt is a water
absorbing press belt, in particular a press felt.
3. The machine of claim 1, wherein said press nip is a separate
press nip.
4. The machine of claim 1, wherein said press roll is a shoe roll
to form an extended press nip.
5. The machine of claim 1, wherein said press roll is arranged
within a loop that is created by said inner belt and said mating
roll is arranged within a loop that is created by said lower press
belt, or that said press roll is arranged within the loop that is
created by said lower press belt and that said mating roll is
arranged within the loop that is created by said inner belt.
6. The machine of claim 1, wherein said mating roll is a suction
roll.
7. The machine of claim 1, further comprising a steam blow box
assigned to the fibrous web before said press nip when viewed in a
machine direction, in order to impinge the fibrous web with
steam.
8. The machine of claim 1, further comprising a suction device
located within a loop that is created by said inner belt, said
suction device being located prior to said press nip when viewed in
machine direction.
9. The machine of claim 8, further comprising a blower hood
assigned to said suction device for direct impingement of the
fibrous web with steam and/or hot dry air and/or hot moist air.
10. The machine of claim 1, further comprising a suction guide roll
which is partially wrapped by said inner belt, said suction guide
roll being arranged within a loop created by said inner belt and
between said press nip and said transfer roll.
11. The machine of claim 10, wherein said suction guide roll is
partially wrapped in a wrap region by a permeable press belt in
direct contact with the fibrous web.
12. The machine of claim 11, further comprising a hood positioned
within a loop created by said press belt and in said wrap region
for indirect impingement of the fibrous web with steam and/or hot
dry air and/or hot moist air.
13. A method for the production of a fibrous web, in particular a
tissue web, comprising the steps of: forming the fibrous web in a
forming region, the forming region being where a forming roll and a
permeable inner belt that at least partially wraps around said
forming roll comes together with an outer belt; dewatering the
fibrous web in a press device which is located immediately
downstream from the forming region, the press device having a press
nip which is formed by a press roll and a mating roll; supportedly
carrying the fibrous web between said inner belt and a lower press
belt through said press nip, wherein said press nip is a first
press nip of the press device through which the fibrous web is
routed; drying the fibrous web by a drying cylinder that is located
downstream from the press device, wherein the fibrous web is
delivered, in a transfer nip that is formed between a transfer roll
and said drying cylinder, to a heated surface of said drying
cylinder, the fibrous web being transported from the forming region
to the transfer supported on said inner belt, said inner belt being
textured, so that the fibrous web becomes textured and the fibrous
web is carried supported between said inner belt and a lower press
belt through said press nip.
14. The method of claim 13, wherein said lower press belt is a
water absorbing press belt, in particular a press felt.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The invention relates to a machine for the production of a
fibrous web.
2. Description of the Related Art
[0002] Document EP2796617 B1 discloses a Crescent former paper
machine for the production of tissue paper. The tissue web is
formed in a forming region between an outer wire and a felt and in
a first configuration it is carried--supported on the felt together
with an additional felt, through a shoe press and is subsequently
transferred in a roll nip to the surface of the downstream drying
cylinder. With this configuration, heavy tissue papers having a
high specific volume can be produced energy efficiently. In a
suggested second configuration, the tissue web is not routed
through the shoe press nip but is transferred from the forming
region directly onto the surface of the downstream drying cylinder.
In addition, the arrangement of a suction felt guide roll for
conditioning of the felt prior to the shoe press is proposed. A
disadvantage of this arrangement is a limited increase in quality,
in particular of the specific volume of the tissue web.
[0003] A similar Crescent former paper machine is disclosed in U.S.
Pat. No. 6,547,924 B2. However, instead of the felt, an impermeable
textured belt is provided in the former on which the tissue web is
carried through a simply felted shoe press to the drying cylinder.
The disadvantage of this machine exists in that there is
insufficient dewatering in the shoe press. Only a low dry content
can be achieved in the tissue web before the drying cylinder. This
results in a high energy expenditure due to thermal drying of the
web in the region of the drying cylinder. Moreover, the production
speed and thus the output are thereby limited.
[0004] What is needed in the art is a machine and a method to
improve the quality of the produced tissue web, in particular the
specific volume, wherein good runability at high production speed,
with efficient energy use and simple construction are
considered.
SUMMARY OF THE INVENTION
[0005] The present invention produces a tissue web, with a forming
region including a forming roll and a permeable inner belt which at
least partially wraps around a forming roll together with an outer
belt for the formation of the fibrous web, with a press device
immediately downstream from the forming region. The press device
includes a press nip which is formed by a press roll and a mating
roll for additional dewatering of the fibrous web, wherein the
press nip is the first nip of the press device. The fibrous web is
carried through the press nip supported between the inner belt and
a lower press belt. A drying cylinder is downstream from the press
device, wherein the fibrous web is carried and supported on the
inner belt--in a transfer nip which is formed between a transfer
roll and the drying cylinder--from the forming region until the
transfer to the heated surface of the drying cylinder.
[0006] An embodiment of the present invention includes a machine
for the manufacture of a fibrous web, in particular a tissue web,
having a forming region with a forming roll and a permeable inner
belt, which at least partially wraps around the forming roll
together with an outer belt for the formation of the fibrous web.
There is a press device immediately downstream from the forming
region that includes a press nip which is formed by a press roll
and a mating roll for additional dewatering of the fibrous web. The
press nip is the first nip of the press device, wherein the fibrous
web--supported between the inner belt and a lower press belt--is
carried through the press nip. There is a drying cylinder
downstream from the press device, wherein the fibrous web is
carried--from the forming region until the transfer in a transfer
nip which is formed between a transfer roll and the drying
cylinder--supported on the inner belt to the heated surface of the
drying cylinder.
[0007] It is fundamental according to the present invention that
the inner belt for providing texture to the fibrous web is textured
and that the transfer roll is in the embodiment of a shoe roll in
order to provide an extended transfer nip.
[0008] The machine of the present invention is characterized by a
simple construction with which a fibrous web, in particular a
tissue web having a high specific volume, and for which at the same
time a high dry content can be achieved in the press device, can be
produced reliably at a high speed. As a result of forming the
fibrous web on the textured inner belt the web obtains a texture,
which results in a high specific volume. This is maintained
substantially even after running through the press nip, since the
texture of the inner belt protects the texture of the fibrous web
during the compression process. The compressibility of the inner
belt is preferably less than that of the lower press belt.
[0009] The inner belt is permeable, in other words air and water
permeable. This allows two-sided dewatering of the fibrous web in
the press nip, wherein the extracted water is partially, in other
words to a low extent, absorbed by the inner belt and the lower
press belt. The lower press belt, which is in contact with the
fibrous web, can be optimized in regard to quality, for example the
specific volume of the produced fibrous web and a coordinated water
absorption. This allows gentle dewatering without damaging or
crushing the fibrous web. Thus, higher liner forces can be run in
the press nip. Web travel without transfer between two clothings
allows a reliable and stable operation of the machine, even at high
output and speed. The transfer roll in the embodiment of a shoe
roll is advantageous in the transfer of the fibrous web from the
inner belt to the heated surface of the drying cylinder. Due to the
texture of the inner belt that is impressed into the fibrous web,
the web is only selectively compressed in the transfer nip, which
is operated at only a low line force or low forming pressure. Thus,
the increased dwell time of the fibrous web in the press nip has a
positive effect on the transfer to the drying cylinder.
[0010] An additional advantage of the solution is the compact
design in terms of the low space requirement in regard to the
height of the machine. The length of the lower press belt can be
kept short. The routing of the felt of the lower press belt can
thus extend exclusively above the machine floor. This eliminates
the requirement for a basement. Thus, this machine can also be
installed in existing machine halls without basements, for the
production of high-grade tissue webs with a high specific volume,
for example for kitchen towels.
[0011] The inner textured belt can be a woven belt. It can also be
in the embodiment of a permeable, at least on the fibrous web side,
textured membrane or film.
[0012] The drying cylinder can be designed as a Yankee drying
cylinder, in particular when producing fibrous tissue webs. The
design of Yankee drying cylinders is known. They are characterized
for example by large diameters in excess of 6 m and are steam
heated.
[0013] For the production of certain tissue types with lower
requirements in regard to the specific volume and higher demands in
regard to production performance, this machine can be converted
easily and cost effectively. For this purpose, the inner textured
belt can be replaced by a conventional press felt and the press
device can be deactivated. This means that the press device is
either bypassed by the travel path of this press felt or that this
press felt is routed through the opened press nip. This arrangement
is thus consistent with a known Crescent former machine.
[0014] In one advantageous embodiment, the lower press belt is
designed as a water absorbing press belt, in particular as a press
felt. The press roll can be arranged within the loop that is
created by the inner belt and the mating roll can be arranged
within the loop that is created by the lower press belt. It is also
conceivable to arrange the press roll within the loop that is
created by the lower press belt and to arrange the mating roll
within the loop that is created by the inner belt.
[0015] Moreover, the press nip can be designed as a separate press
nip, in other words as a single press nip. This results in a simple
design of the machine.
[0016] The press roll can be designed as a shoe roll to form an
extended press nip. Thus, higher line forces can be run in the
press nip. The extended press nip in this shoe press at the
beginning of the press device, that is directly after the forming
region allows gentle dewatering without damaging or crushing the
fibrous web. At the same time, a higher dry content can be achieved
in the fibrous web than is the case for example with a belt
press.
[0017] In certain cases it is also possible to design the press
roll as a solid surface roll.
[0018] The mating roll may be in the embodiment of a suction roll.
As a result dewatering, in particular the direction of dewatering,
can be influenced.
[0019] To increase the temperature and to improve the
dewaterability of the fibrous web, a steam blow box can be assigned
to the fibrous web before the press nip, in order to impinge the
fibrous web with steam.
[0020] In one possible practical embodiment a suction device,
located within the loop that is created by the inner belt, is
arranged prior to the press nip when viewed in machine direction.
This enables the texture of the fibrous web that was produced by
the inner textured belt to be stabilized and maintained. The
suction device is supplied with vacuum.
[0021] A blower hood may be allocated to the suction device for
direct impingement of the fibrous web with steam and/or hot dry air
and/or hot moist air.
[0022] In one conceivable further advancement a suction guide roll,
which is partially wrapped by the inner belt, is arranged within
the loop created by the inner belt and between the press nip and
the transfer roll. The suction guide roll can be supplied with
vacuum. Web travel can thereby be stabilized and the dry content
for certain fibrous web grades can be increased prior to the drying
cylinder. This arrangement is especially advantageous if the
transfer roll is in the embodiment of a shoe press roll, according
to the present invention. This ensures a reliable transfer of the
fibrous web to the drying cylinder, even at a high dry content.
[0023] Moreover, the suction guide roll can be partially wrapped by
a permeable press belt in direct contact with the fibrous web. The
press belt can have an increased belt tension, for example, of
higher than 20 kN/m, preferably higher than 30 kN/m. As a result
the dry content of the fibrous web can be even further increased in
certain fibrous web grades prior to transfer onto the drying
cylinder.
[0024] In one additional possible embodiment a hood can be provided
within the loop created by the press belt and in the region of the
wrap for indirect impingement of the fibrous web with steam and/or
hot dry air and/or hot moist air. Thus, the dry content of the
fibrous web can be even further increased in certain fibrous web
grades prior to the transfer to the drying cylinder.
[0025] The lower press belt is preferably designed as a water
absorbing press belt, in particular as a press felt.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] 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:
[0027] FIG. 1 illustrates a first embodiment of a machine according
to the present invention in a simplified schematic
representation;
[0028] FIG. 2 illustrates a second embodiment of a machine
according to the present invention in a simplified schematic
representation; and
[0029] FIG. 3 illustrates a third embodiment of a machine according
to the present invention in another simplified schematic
representation.
[0030] Corresponding reference characters indicate corresponding
parts throughout the several views. The exemplifications set out
herein illustrate embodiments of the invention and such
exemplifications are not to be construed as limiting the scope of
the invention in any manner.
DETAILED DESCRIPTION OF THE INVENTION
[0031] Referring now to the drawings, and particularly to FIG. 1
there is shown a first embodiment of an inventive machine 1 of the
present invention in a simplified schematic representation. Machine
1 for the production of a fibrous web 2, in this example a tissue
web, includes a forming region having a forming roll 5 and an inner
belt 4 which, together with an outer belt 5, wraps at least
partially around forming roll 5.
[0032] A headbox 6 feeds a fibrous stock suspension between belts
3, 4. This suspension is dewatered primarily in the common
wrap-around region of belts 3, 4 in the region of forming roll 5,
thus forming tissue web 2 and being transported on inner belt 4
onto and through a directly following press device 7. In this
example, press device 7 includes a press roll 8 arranged at the top
and a mating roll 9, arranged at the bottom, which together form a
press nip 24 for further dewatering of tissue web 2. Mating roll 9
and press roll 8 can also be arranged conversely. Mating roll 8 is
arranged as a suction roll with applied vacuum.
[0033] Press nip 24 of press device 7 is the first press nip 24
after the forming region. Upstream from press nip 24, viewed in a
machine direction 22, a suction device 21, in this case a suction
box 21 which is supplied with vacuum is located within the loop
created by inner belt 4. A blower hood 20 is assigned to suction
box 21 for direct impingement of fibrous web 2 with steam and/or
hot dry air and/or hot moist air. In addition to tissue web 2 and
inner belt 4, a lower press belt 11, which is in direct contact
with tissue web 2, also runs through press nip 24. Lower press belt
11 is in the embodiment of a water absorbing press felt.
[0034] After additional dewatering of tissue web 2 in press device
7, tissue web 2, supported on inner belt 4 is led around a transfer
roll 13 in the embodiment of a shoe roll. The latter, together with
a drying cylinder 14, in this case a Yankee drying cylinder 14,
creates a transfer nip 12 in which tissue web 2 is transferred from
inner belt 4 onto the heated surface of Yankee drying cylinder 14
and continues to be thermally dried. Tissue web 2 is moreover
supplied with hot air and/or overheated steam by way of a dryer
hood 15 that is located in the region of Yankee drying cylinder 14.
Tissue web 2 is subsequently creped on a doctor blade 16 and is
removed from the surface of the Yankee drying cylinder and is
transported directly or indirectly to a winding station, which is
not illustrated herein.
[0035] Tissue web 2 is thus transported by one single belt 4 from
the forming region to Yankee drying cylinder 14. According to the
present invention, a transfer to an intermediate belt is not
required for the production of qualitatively high-grade tissue webs
with a high specific volume. This promotes good runability of the
machine. The inner belt is permeable, in other words air and water
permeable, and at least on the side that is in contact with tissue
web 2 it is textured in order to provide texture to tissue web 2.
Providing tissue web 2 with texture causes a high specific volume
which is also referred to as bulk. In this example, the inner
textured belt is a woven belt. It can also be in the embodiment of
a permeable--at least on the fibrous web side--textured membrane or
film.
[0036] The compressibility of inner textured belt 4 is less than
that of the lower press belt 11. This protects the texture of
tissue web 2 from being crushed when running through press nip 24.
Machine 1 according to the present invention makes two-sided
dewatering of fibrous web 2 in press nip 24 possible, wherein the
extracted water is partially absorbed by inner belt 4 and primarily
by lower press belt 11. Lower press belt 11, which is in contact
with fibrous web 2, can be optimized in regard to quality, for
example the specific volume of produced fibrous web 2 and in regard
to the dewatering capacity. In order to form an extended transfer
nip 12 together with Yankee drying cylinder 14, transfer roll 13 is
designed as a shoe press roll.
[0037] Machine 1 is very compact in regard to its height. The
length of lower press belt 11 is short. The travel path of the felt
of lower press belt 11 is arranged exclusively above machine floor
23. This eliminates the requirement for a basement which is
necessary in known machines for the production of tissue webs
having high bulk. Thus, this machine can also be installed in
existing machine halls without basements, for the production of
high-grade tissue webs 2 with a high specific volume, for example
for kitchen towels.
[0038] Now, additionally referring to FIG. 2 there is shown a
second embodiment of inventive machine 1 in a simplified schematic
representation. It differs from the embodiment shown in FIG. 1 in
regard to a suction guide roll 17 which is arranged within the loop
created by inner belt 4 and between press nip 24 and transfer roll
13 and which is partially wrapped by inner belt 4. Web travel can
thereby be stabilized and the dry content for certain tissue web
grades can be increased prior to drying cylinder 14. This
arrangement is especially advantageous together with transfer roll
13 which, according to the invention is designed as a shoe press
roll.
[0039] Now, additionally referring to FIG. 3 there is shown a third
embodiment of inventive machine 1 in simplified schematic
representation. It differs from the embodiment shown in FIG. 2 in
that suction guide roll 17 is partially wrapped by a permeable
press belt 18 and in that it is in direct contact with tissue web
2. The press belt applies pressure on tissue web 2 to increase the
dry content. Press belt 18 has an increased belt tension of more
than 20 kN/m, preferably more than 30 kN/m. The dry content of
tissue web 2 can thus be increased in certain tissue web grades
prior to the transfer to drying cylinder 14. A hood 19 is provided
within the loop created by press belt 18 and in the region of the
wrap for indirect impingement of the fibrous web with steam and/or
hot dry air and/or hot moist air. Thus, the dry content of fibrous
web 2 can be even further increased in certain tissue web grades
prior to the transfer to the drying cylinder 14.
[0040] Corresponding elements shown in drawings of design examples
are identified with the same reference numbers. The function of
such elements in the individual drawings are consistent with one
another if no deviances are described that would lead to
contradictions. Repetitive descriptions are therefore dispensed
with. It is also pointed out that differing characteristics of the
illustrated design examples are interchangeable and can be combined
with one another. The invention is therefore not restricted to the
illustrated characteristics combination of the illustrated design
examples.
[0041] While this invention has been described with respect to at
least one embodiment, 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.
COMPONENT IDENTIFICATION LISTING
[0042] 1 Machine [0043] 2 Fibrous web [0044] 3 Outer belt [0045] 4
Inner belt [0046] 5 Forming roller [0047] 6 Headbox [0048] 7 Press
device [0049] 8 Press roll [0050] 9 Mating roll [0051] 11 Lower
press belt [0052] 12 Transfer nip [0053] 13 Transfer roll [0054] 14
Drying cylinder [0055] 15 Dryer hood [0056] 16 Doctor blade [0057]
17 Suction guide roll [0058] 18 Press belt [0059] 19 Hood [0060] 20
Blower hood [0061] 21 Suction device [0062] 22 Machine direction
[0063] 23 Machine floor [0064] 24 Press nip
* * * * *