Note: Descriptions are shown in the official language in which they were submitted.
Z0041Z;~
The invention relates to a method for forming a paper or
paperboard web from fibrous material. The method is to be
applied in the wire section of a paper making machine or the like
consisting of a bottom wire loop with the main portion of its top
run being essentially horizontal, and of a top wire loop working
in conjunction with it. In the method the fibre slurry coming
out of the headbox of the paper making machine is fed to the
first part of the top run of said bottom wire loop, which forms
the first dewatering zone. After that the partly formed fibre
layer travels to the second dewatering zone, in which said top
wire loop is made to cover the partly formed fibre layer in a way
that water removal from the fibre layer continues at least in two
stageR in the area of said secona dewatering zone. Then the top
wire loop is separated from the nearly formed web that is led to
follow the run of the bottom wire loop forward to the next
processing stages of the web.
The invention also relates to a web forming device for
performing the method of the invention. The device comprises a
bottom wire loop with the main portion of its top run being
essentially horizontal and a top wire loop working in conjunction
with it, as well as a headbox that is arranged to feed the jet of
fibre 81urry to the single-wired first Part of the top run of the
bottom wire loop, after which there is a double-wired forming
zone that i6 l$mited between the common travels of the bottom and
top wires. In this zone, inside the bottom wire loop and the top
wire loop there are different elements and element groups
affecting the water removal.
According to the oldest methods for forming continuous paper
or paperboard webs, which are still most commonly applied, the
forming of the web takes place on a so called horizontal
fourdrinier wire section. In these methods water is removed from
fibre slurry only in one direation downward at the full length of
the wire section. Due to the operating principle of such wire
section the top and bottom sides of the finished sheet have
different properties, i.e. the top side of the paper is smoother
than the bottom side where pattern or wiremarking, caused by the
forming wire, can be seen more or less clearly. The top and
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bottom sides of the sheet also differ from each other as to the
fibre composition; the top side of the web contains more fine and
short fibres than the bottom side from which a con~iderable
amount of fines have been drawn during and as a result of the
one-way dewatering proces~. The difference between the paper
sides is not detrimental when for instance wrapping paper or
packaging cardboard is concerned. It is important that the sides
of paper intended e.g. for printing of book~ and new6papers be
the same as to the fibre composition and other properties. The
difference between the paper sides i8 called two-sidedness.
A large number of paper machine types designed especially
for reducing the two-sidedness of paper are known. Between these
types two main groups can be distinguished, i.e. the actual twin-
wire formers and the 80 called hybrid formers. Web formation on
the actùal twin-wire formers takes place from the beginning to
end between two wires. On the hybrid formers the web is formed at
first on one wire, after which the partly formed web is led to
the dswatering zone formed between the two wires where the final
mutual position of the fibres is stabilized.
One advantage of the hybrid former6 is that they can be made
from the exi~ting fourdrinier wire sections by means of
relatively simple modifications. The most essential change is to
place the top wire loop in the middle or last part of the bottom
wire top run in order to work with it together. This will allow-
in addition to the fact that the quality of the resultant paper
can be improved - a more efficient water removal on the wire
section and by that means also the increase of the paper machine
speed. One hybrid former of this kind has been disclosed in the
PI-application 820742 of the present applicant. The described
machine i~ primarily intended for producing newsprint and similar
printing grades with a working speed up to and over 900 metres
per minute.
A significant weakness of the above mentioned former6 is the
~act that they are not in general suitable for producing heavy
paper and board grades. This i8 due to the fact that at the
beginning of the double-wired portion following the first
dewatering zone of the single wire, the run of the wires and the
fibre layer between them, partly already formed to a web, is
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abruptly caused to curve quite sharply either over the surface of
the rotating roll or the stationary so called forming shoe. The
curving cause~ internal fracturing which becomes larger as the
web becomes thicker. Thiæ means that the fibre layer i6 expo6ed
to water removal pres6ure between the wires, which pres6ure is in
direct ration to the tension of the outer wire and in rever6e
ratio to the radius of curvature of the surface in que6tion.
The 6pace arrangement6 and other 6tructural factors cau6e
that in the well-known hybrid former6, e. g. in the Finni6h
Patent Application 820742, the radius of curvature of the
reversal element of the wires, that i8 the 6hoe or the roll, is
80 small that the sudden compressing effect directed to the
forming web is far too great in case that heavier grades of paper
and board are manufactured on the former in que6tion. Too heavy a
compression causes in thi6 case damage to the fibre layers and
decreases the properties of the fini6hed product, especially it6
6trength, but also for instance the printability. In the wor6t
ca6e too heavy a compression re6ult6 in 60 called ~6pla6hing~ of
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the web and may cau6e production break6. - ~ ~-
It is an object of the pre6ent invention i6 to create a wire
section of a paper making machine of hybrid former type a6 well
a8 a method to be applied in it, in which 6pecial attention ha6
been paid to eliminating the problems in connection with the
production of heavier grades of paper and board. The
construction according to the invention al60 allows the
production of lightweight paper grades at high speeds; therefore,
the hybrid former applying the invention is meant to be operative
in a very wlde basis weight area, that is even 50-1000 grams per
square metre.
It is another object of the invention to create a device by
means of which the water removing pres6ure directed to the fibre
layer increaee6 progre66ively in the running direction of the
wires.
I n general terms and con6idering one aspect of the
invention, a method i6 provided for forming a paper or paperboard -~ -
web from a fibrou6 material in the wire section of a paper making
machine or the like, which wire 6ection is operatively as60ciated
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with a headbox and consist6 of a bottom wire loop and a top wire
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loop a main portion of a top run of the bottom wire loop being
generally horizontal, ~aid top wire loop having a bottom run
di~posed in proximity to and 61ightly convergent with a portion
of 6aid top run of the bottom wire, the convergence between the
S two run6 being directed away from 6aid headbox, 6aid method
comprising the steps of~
a) delivering fibrous slurry from a headbox to a first
dewatering zone formed on a first part of the top run of
6aid bottom wire loop, 6aid first part being disposed at an
upstream end portion of the top run;
b) sub6equently delivering a partly formed fibre layer produced
in the fir6t dewatering zone from 6aid 61urry to a second
dewatering zone, said second dewatering zone being dispo6ed
at a portion of the top run which is in proximity of and is
~5 generally overlapped by the bottom run of the top wire loop,
whereby the partly formed fibre layer i6 dewatered, during
its passage through the second dewatering zone, at both
6urface6 of the fibre layer into a partly dewatered fibrou6
web, the web being di6po6ed between said top and bottom runs
of 6aid wires;
c) at a downstream end portion of the first dewatering zone
interrupting the dewatering through the top run of the
bottom wire by means of a group of dewatering prevention
elements arranged in operative contact with a generally
downwardly facing inner surface of the bottom wire loop at
said downstream end portion;
d) maintaining the interruption of the dewatering through the
top run of the bottom wire throughout the pas6age of the web
through 6aid second dewatering zone while dewatering the web
through the bottom run of the upper wire loop;
e) said slurry, said partly formed fibre layer and said web
being supported on a generally planar wire table formed by
the upper run of the lower wire loop and extending from said
headbox to at lea6t a downstream end of the second
dewatering zone;
f) after the pas6age of the web through the second dewatering
zone, maintaining the web between the two wires while
pa6sing it over a curved third dewatering zone which is
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20041Z3
disposed downstream of the second dewatering zone; and
g) moving the top wire loop such that its bottom run gradually
æeparates from the partly formed while maintaining the web
positioned on the adjacent section of the bottom wire loop
and moving it along the bottom wire loop to a next ~ -
processing stage.
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In another aspect, but still considering the invention ingeneral terms, a web forming device is provided compricing a
bottom wire loop including a top run whose main portion of i8
generally horizontal, and a top wire loop working operatively
associated with the bottom wire loop, and a headbox arranged to
feed a ~et of fibre slurry to a single-wired first part of the
top run of the bottom wire loop, said fir6t part of the top run
forming a first dewatering zone, said fir6t dewatering zone being
followed by a double-wired forming zone forming a 6econd
dewatering zone through which the upper run of the bottom wire
loop and the lower run of the top wire loop are adapted to travel
along a common path with a formed web sandwiched therebetween,
there being web forming and wire guiding elements disposed inside
each of the wire loops, the second dewatering zone being
generally planar over virtually the entire length thereof and
forming an immediate and generally coplanar extension to the
single-wired first dewatering zone, said first and second
dewatering zones coinciding with a planar wire table formed by a
substantial part of the top run of said bottom wire loop, said
device further including a third dewatering zone downstream of
the second dewatering zone, through which third dewatering zone
the upper run of the bottom wire loop and the lower run of the
top wire loop are adapted to still travel along a common path
with a formed web sandwiched therebetween, said third dewatering
zone being curved in coincidence with curved guide means.
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In a preferred embodiment of the invention the straight, -
first stage of said double-wired portion has been equipped with a
two-part dewatering device consisting of wire supporting elements
inside the bottom wire loop and a suction chamber system located
in the equivalent area inside the top wire loop.
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The first single-wired dewatering zone in this invention is
most suitable when it is relatively short and the dry content as
a result of water removal in its area before the second
dewatering zone is approximately 1-4 per cent. Due to the
shortness of the first dewatering zone only a few dewatering
elements, such as foils, are needed to support it; therefore, the
effect of water flow removing fine substances and directed
perpendicularly to the forming web is of minor effect here. In
this first dewatering zone the friction caused by the dewatering
elements against the wire is also insignificant which, for its
part, reduces the wear of the wire and the need of energy on the
wire section.
The subsequent part of the dewatering area which comprises
two wires may, depending on the construction variation applied in
each case, include several, minimum two, zones, a second and a
third dewatering zone, each operating in a different fashion. The
second dewatering zone, unlike the conventional hybrid former
technology, forms a linear or coplanar immediate extension to the
first single-wired dewatering zone. In the area of this second
dewatering zone, the top wire loop is directed to approach the
bottom wire loop and the fibre layer on its surface at a very
narrow angle, e.g. 2-5 degrees. In this stage the water removal
pre6sure directed to the partly formed web is relatively slight,
which means that the gentle dewatering process continues. The
point where the top wire loop meets the fibre layer can vary
depending e.g. on the intersecting angle and thickness of the
fibre layer. To avoid the need for the web forming section to be
too long as a whole, water removal has, however, to be
intensified, but still very gently. Furthermore, water removal
should in this stage be forcefully directed to take place through
the top wire loop, in which case the dewatering device located
inside the top wire loop and disclosed in the SE-application
8703468 of the applicant can be used. The first part of the
device in questlon is a water doctor of 80 called auto-sluice
type, which is combined with a corresponding water collection
chamber suitably connected to a suction source. The dewatering
device further incorporates at least one water collection pit
arrangement that comprises several foils and is connected to the
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2004123
suction source. Opposite to this dewatering device located insidethe top wire loop there is further, inside the bottom wire loop,
a set of wire supporting elements which are on the one hand meant
for reducing the water removal through the botto~ wire and on the
other hand for directing pressure in this area to the fibre layer
between the top and bottom wires - in other words to the partly
formed web - in order to increase the water removal and the
suitable pulse of the pressure, thanks to which the formation of
the web improves. These wire supporting elements are loaded
against each bo~tom wire loop e.g. by means of pneumatic hoses.
Compression against the web is thus self-adjusting. One es6ential
advantage of thi6 arrangement is that the water removing pressure
directed to the fibre layer between the wires i6 increa6ed in the
desired way gradually in the running direction of the wires
without a 6udden pres6ure peak at the beginning of the double-
wired portion as is the case on conventional hybrid formers.
When the forming web has reached a dry content of 5-10 per
cent after the second dewatering zone, which is naturally
dependent on the basis weight of the paper or paperboard to be
made and on the speed of the machine, a 6tronger compression than
before can be directed in this stage towards the web between the
top and bottom wlres. ~his is created by leading the travel of
the web, in the thlrd dewatering zone, over one or more curved
surfaces which can be either rotating or stationary. After this
stage the dry content of the web is 14-16 per cent depending on
the productlon conditions, and in this third zone, the top wire
can be separated from the web supported by the bottom wire, after
which the web continues its travel forward to the next etages of
the process, for instance into the press section of the paper
machine.
The invention will now be described in detail with reference
to exemplary embodiments shown in the enclosed figure6. The
invention i6 not, however, limited to the details of the examples
ln a narrow sense.
Fig. 1 shows in a side profile diagram a web forming device
25 according to the invention.
Fig. 2 shows another embodiment for applying the invention.
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Fig. 3A shows a dewatering device installed inside the top
30 wire loop.
Fig. 3B shows a variant of the dewatering device according
to Fig. 3A.
Fig. 4A is a partial picture of a so called auto-slice
device that is part of the dewatering device shown in Figs. 3A
and 3B.
Fig. 4~ illustrates an alternative variation of the detail
6hown in Fig. 4A.
~he web forming device ghown in Fig. 1 comprises a headbox 1
and a bottom wire loop ~, which travels about a breast roll 3,
wire guide rolls 4, a forming roll 6 and a couch roll 1- Inside
the bottom wire loop, in the region of what i6 referred to as a
first dewatering zone, there is provided a group of dewatering
elements 5 and in the subsequent region, referred to as a second
dewatering zone, a group of wire cUpporting elements ~ 9b, 9c is
disposed, together with as well a suction box 8 which is located
between the forming roll 6 and the couch roll 7 on the bottom
wire run inclined downward. Thus, as i6 known, the two wires form
a dewatering region between their slightly convergent horizontal
runs. The dewaterlng region, of course extends to an area before
the top wire approach to the bottom wire and past the planar
horlzontal area shown in the drawinge and extending from the
headbox as will be described later.
The web forming device further comprises a top wire loop
which is guided by guide rolls 11, l1a and 11b and which covers
the bottom wire loop in the area of the second dewatering zone.
Inside the top wire loop there is further a dewatering device ~
which is shown in more detail in Figs. 3A and 3B. The first part
of the device 12 is a water removing doctor or sluice blade of
the type typically associated with the suction chamber of a
suction box. As is known in the art, the sluice blade serves the
purpose of maintaining a wave of water at an upstream end of the
suction opening in the dewatering device 12 in order to improve
performance of and to reduce noise caused by the dewatering
device 12. The wave of water generated by the sluice thus
provides what could be referred to as a sealing effect at the
upstream edge of the suction opening of the dewatering device 12.
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20041Z3
Furthermore, the dewatering device comprises two water collection
pits with the bottom part formed as foil blades which are in
contact with the top wire 10.
The operation of the web forming device i6 as follows: The
5 headbox feeds the stock to the horizontal fir6t part 2a of the
bottom wire loop 2 that is the first dewatering zone, in which
area water removal is gentle, by means of suitable, relatively
few, water removing elements 5. The fibre layer W formed on the
surface of the bottom wire loop 2 continues its travel to the
10 second dewatering zone which is formed wh~le the top wire loop 10
is directed close to the bottom wire loop 2 at a narrow angle ~
The most suitable grade of the angle i6 2-5' which is obtained by
ad~usting the position of the guide roll lla of the top wire 10
vertically (marked with an arrow).
The second dewatering zone i6 divided into several stages.
The dewatering device 12 located inside the top wire loop and the
inside wire supporting elements 9 of the bottom wire loop 2
working in conjunction with it form the first stage of the second
dewatering zone. The first dewatering zone 2a and the dewatering
20 zone are in the same horizonal plane. The plane extends through
the second dewatering zone up to the forming roll 6 where it
forms what is referred to as a third dewatering zone. The forming
roll 6 deflects the path of the travel of the wires 2 and 10
downward at an angle as large a6 the sector ~ where the common
25 travel of the wires 2 and 10 iB guided by the forming roll 6. The
~eotor b is thus third dewatering zone. Compression between the
wires 2 and 10 removes further water from the formed web W.
Water is thrown by centrlfugal force into a water collection pit
L~ ~nd removed through a channel L~. Between the forming roll 6
30 and the couch roll 7 the wire 10 is separated, by means of the
roll llb, from the formed web W which is supported on top of the
wire 2, and the web continue6 it6 travel up to the roll 7. The
suction box 8 is for the purpose of ensuring that the web W does
not follow the wire 10 that returns to the roll lla. Close to the
35 couch roll 7 there is a pick-up roll 14 with a felt 15, by means
of which the web W is transferred from the forming section into
the press section (not presented).
The web forming section shown in Fig. 2 comprises a headbox
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.
101 and a bottom wire loop 1~, the travel of which is mainly
guided by a breast roll 103, forming roll 106, couch roll 107 and
wire guide rolls 104. The web forming gection of Fig. 2 also
comprises a top wire loop 110 and wire guide rolls which guide
the travel of the top wire loop and are marked with reference
numbers 111, llla, 114, and a dewatering device 112.
The web forming device of Fig. 2 functions in the same way -
as the one shown in Fig. 1. The difference between the
embodiments of Figs. 1 and 2 is in the construction and operation
of the dewatering devices 12 and 112 as well as in the
positioning of the forming rolls 6 and lQ~ compared to the main
horizontal wire plane T-T of these web forming sections. The end
part of the dewatering device 112 curve6 upwards and leads the
common travel of the wires 102 and 110 to the forming roll 106,
the highest point of which is es6entially above the main
horizontal plane T-T of the wire 102. Compression between the - -~
wires 102 and 110 in the third dewatering zone, which - in the
embodiment of Fig. 2 - is the upwardly and then downwardly curved
area of the forming roll 106 removes water from the web W under ~ -
forming, and the water is thrown into a water collection pit 113.
The travel of the wires 102 and 110 is returned to the original
plane T-T by means of a wire guide roll 114. The top wire loop
110 is deflected away from the travel of the wire 102 in the same
way as in the arrangement of Fig. 1. The bottom wire 102 together - - -
wlth the web W 18 supported by a suction box 108 and moves over
the couch roll 107 to the run between this roll and a drive roll :
15~L from which the web W can be moved by means of a pick-up
roll 14 and a pick-up felt forward into the press section of the ---
paper machine in the Way known per se. - ;~
Fig. 3A illustrates a dewatering device 12 of a forming
section according to Fig. 1 with its most important construction
details, and a supporting element group 9 of the bottom wire
cooperating with it. ~
The dewatering device 12 consists of an integrated ''.r~ ''."''~7''':'.',''''.
combination of three suction and water collection chambers 16, 17 ~ ~ -
and 18 in which the different chambers are separated from each
other by partitions 17b and 18b. An air opening 19 and a
discharge water channel 20 have been connected to the suction ~9
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source (not presented) in each chamber 16, 17 and 18. A water
collection channel 16a that is part of the first suction chamber
16, is formed between the main beam 16b and the de~lector 1~ of
the dewatering device. At the lower end of the channel 16a there
is a transverse doctor or foil ~1 and a blade ~ which is
adjustable by means of rods 23. These form a sluice A that
extends over the width of the wire former and can be adjusted in
cross profile. As already mentioned above, the sluice serves the
purpose of maintaining a wave of water at an upstream end of the
suction opening in the dewatering device 12 in order to improve
performance of and to reduce noise caused by the dewatering
device 12. Through this sluice the water compressed through the
fibre layer between the wires 2 and 10 is thrown into the first
chamber 16.
The foil or doctor 21 of the device 12 shown in Fig. 3A i6
followed by a group of similar foils 21' and 21'' with their
bottom surfaces in the same plane. The water separated from the
fibre layer is collected by the foils under the suction chamber
16 and led into the suction chamber 17 through a channel 11~ that
is formed between the partition 17b and the deflector 17c.
Correspondingly, the water collected by the next foilæ 21'' is
led into the third suction chamber 18 through a channel 18a that
18 ~ormed between the back wall 1~ and the deflector 18c of the
dewatering device.
The channel 16a of Fig. 3A and the foil doctor 21 with the
blade 22 ad~ustable in relatlon to said doctor form together the
sluice feature as described above. When the wire section is run
at a high speed during the manufacture of lightweight paper
grades, the water separated from the web W enters into the
channel 16a mainly by its own kinetic energy, and then proceeds
lnto the suction chamber 16. When heavier board grades are
produced on the former at low speeds, the operation of the sluice
system may have to be complemented by a stronger suction, the most
suitable vacuum being 6-8 kilopascal. In this stage the amount of
water to be removed and directed upwards can be affected by
ad~usting the height of the sluice A between the blade 22 and the
foil 21. The same applies partly to the grade of the vacuum
balance.
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2004123
The dewatering effect of the sluice system of Fig. 3A with
the first suction chamber 16 i6 local and is limited close to the
leading edge of the first foil or doctor 21. The dewatering area
of the second suction chamber 17 is wider and determinea by the
S number of foils 21~, of which, as an example, there are four in
Fig. 3. The effect of the foils 21~ is ba6ed on cooperation with
the wire supporting element6 9 located inside the bottom wixe
loop 2. The supporting elements 9 have been de6crlbed in more
detail in Fig. 4A. It i6 essential to these 6upporting element6 9
and their operation that they can bs u6ed in the area of the
dewatering device 12 for creating in a desired way an upwardly
directed pre66ure at the bottom wire 2 which increa6es gradually
and i6 directed to the forming web W and which cause6 the water
removal from the web W to take place mainly through the top wire
loop 10 into the 6uction channel 17a and through it into the
suction chamber 17. The operation of the third 6uction chamber 18
i6 analogical to the 6econd 6uction chamber 17.
The underpres6ure prevailing in the second and third
chambers 17, 18 of Fig. 3A is considerably stronger than that in ~ `
the first chamber, that i6 10-20 kilopa6cal in the chamber 17 and
approximately 15-30 kilopa6cal in the chamber 18 depending on
the quality of the web to be made.
Flg. 3B illustrate6 the dewatering device 112 of the wire
section of Fig. 2. Thls i6 e66entially equivalent to the
dewatering device 12 of Fig. 3A a6 far as the construction and
operatlon are concerned. For thi6 reason generally the same
reference numbers as for Fig. 3A are used for describing Fig. 3B.
The dlfference between the dewatering devices 12 and 112 of
Flg. 3A or 3B 18 the fact that in the construction of the latter - `~
30 the last folls 124' in the suction channel 118a of the third ~;
suctlon chamber 118 have been arranged to make up a contour
curvlng upwards in order to guide the travel of the wires 110 and
102 to the forming roll 106 shown in Fig. 2. Another difference
is in the length of the wire supporting element section 9, 9b, ~ ~
35 9c. The supporting members a of the bottom wire 2, 102 with the ~ ~-
top sides in contact with the bottom wire 2, 102 form together a
generally planar, continuous surface and-are necessary and useful
only at the location opposed to the first and second 6uction
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20041Z3 ~ ~
chambers 16 and 17 of the device 112 located on the upper side of
the wires 102, 110 or 2, 10 (Fig. 3B), while in the device 12
shown in Fig. 3A they are disposed even under the chamber 18.
The function of the suction chambers in the dewatering ~--
devices 12 and 112 of Figs. 3A and 3B is ldentical in principle.
Therefore, it is not neces6ary to explain the construction and
operation of the equipment of Fig. 3B in more detail herein.
Fig. 4A shows as a partial picture the sluice section of the
dewatering devices 12,112 and the internal wire supporting -~ :~
element 6ystem 9 of the bottom wire 2 cooperating in connection
with another.
The water removal process in the devices of Figs. 3A and 4B
takes place as follows: The fibre layer W formed partly on the
surface of the bottom wire loop 2 in the first dewatering zone 2a
15 of the wire former comes to the gap between the wires 2 and 10, ~ -
the angle of which is determined by the height position of the
roll 11a guiding the wire 10 and being adjustable as to its
position. The surface of the fibre layer meets the top wire 10
near the Point ~ (Fig. 4A). This i6 al~o the position of the ` :
20 leading edge of the wire supporting 6ystem 9 6upporting the ~ ~ i
bottom wire loop 2. It is active in causing the water removal
from the fibre layer mainly upwards. The elements 9 of the system -~
are 8upported flexibly on the longitudinal supporting beams 9c
through rubber hoses 9bl, 9b2, 9b3, 9b4... pressurized with air.
The pressure in the hoses 9b1 etc. can be regulated 80 that the
loading of the elements against the bottom wire 2 and the fibre
layer increases gradually in the running direction of the wires 2
and 10. A fairly low pressure is used in the hoses 9b1..., e.g.
10-50 centimetres H20; ~he pressure directed to the forming web W -
~
is rather slight and the water removal pressure is self~ad~usting. The surface of the elements 9 has grooves 9R
extending across the whole width of the wire 2 and allowing a
slight water removal even through the bottom wire. The water
removal process continues in the area between the point B and the
ad~ustable blade 22. A film of water is formed on the inner
surface of the top wire 10 collecting in a sharply wedge-shaped
space between the wire 10 and the blade 22 and the sluice A
between the blade 22 and the foil 21. Water is drawn through the
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20041Z3
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sluice A and the channel 16a into the first chamber 16 of the
dewatering device, either by effect of its kinetic energy and/or
the vacuum prevailing in the chamber. The blade 22 i6 adjustable
in height by means of the adjusting device 23; this allows that
the water amount and possibly even the air amount coming into the
channel 16a can be regulated. The adju6tments in question
regarding both the inter6ecting angle a between the wires 2 and
10 (Fig. 1) and the gluice A leading to the channel 16a, as well
as the regulation of the pressure applied by the supporting
system 9 are naturally dependent on the paper or paperboard grade
to be manufactured.
The sluice system of Fig. 4A based on the use of the
adjustable blade 22 can in certain cases be replaced by the
construction shown in Fig. 4B; then the adjustable blade has been
lS replaced by the roll 22A. The rotating speed and the height
position of the roll, i.e. the distance from the wire 10, haæ
been arranged adjustable. The variable speed drive device of the
roll 22A i8 marked with reference number 22B.
The following claims allow modifications concerning the
details of the invention, departing from the embodiments
di8closed without departing from the scope of the invention as
set forth in the accompanying claims
Accordingly, we wi8h to protect by letters patent which may
1~8ue on thi8 application all such embodiments as properly fall
within the 8cope of our contribution to the art.
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