Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
The present invention relates to a cellulose dewatering
machine.
More particularly, it relates to a cellulose dewatering
machine for producing of paper, with a sieve dewatering device, a
pressing device, a drying device, and a subsequent transverse
cutter.
Cellulose dewatering machines of the above mentioned
general type are known in the art. In the prior art the maximum
obtained speeds in such machines for paper production are in the
range of 50-70 m/min.
The upper limit of the speed of such machines deals
substantially with two factors, namely the dewatering capacity of
the sieve dewatering device and the speed of the transverse
cutter. During the production of paper longitudinal sieves are
used as a rule, and their length is decisive for the dewatering
capacity. The dewatering capacity increases with the length of
the longitudinal sieve, however an elongation of the longitudinal
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sieve by several meters brings an increase of the speed only to a
few m/min.
The transverse cutters normally also do not have higher
speeds than the above mentioned. For obtaining higher speeds,
the transverse cutters must be provided with an overlapping of
the cellulose sheets, which however is not possible due to the
surface roughness of the cellulose sheets.
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SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention
to provide a cellulose dewatering machine, which eliminates the
disadvantages of the prior art.
More particularly, it is an object of the present
invention to provide a cellulose dewatering machine which allows
a significant increase of the speeds when compared with the
existing cellulose dewatering machines.
In keeping with these objects and with others which
will become apparent hereinafter, one feature of the present
invention resides, briefly stated, in a cellulose dewatering
machine of the above mentioned general type, in which the sieve
dewatering device has a round sieve cylinder unit.
The round sieves provide significantly higher speeds in
the region of approximately 90m/min than the longitudinal sieves.
Special round sieves formed as so-called suction round sieves
allow the speeds up to 450 m/min. For obtaining a higher
dewatering capacity, the round sieve cylinder unit can have a
plurality, preferably four suction round sieves. The round sieve
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cylinder unit can also have a turning press, for dewatering the
cellulose web from both sides, as well as a dandy roll press.
For further increase of the speed, the pressing device
can be provided with at least one smooth cylinder, which with its
ground polished surface acts as a one-side smooth cylinder, and
the contact side of the rotating cellulose web mirror-
symmetrically takes the own surface finish. The one-side
smoothness of the cellulose web can be sufficient to provide an
overlapping of the cellulose sheets in the transverse cutter.
The at least one smooth cylinder can cooperate with one or
several suction press rolls for additional improvement of the
dewatering power.
Preferably, for smoothing of both surfaces of the
cellulose sheets, two smooth cylinders can be provided. With the
both-side improvement of the surface finish of the cellulose web,
an overlapping of the cellulose sheets can be obtained in the
transverse cutter without objections and problems. Thereby the
speeds in the region of 150-160 m/min can be obtained.
In order to enhance the subsequent drying, preferably
both smooth cylinders can be provided with dryer hoods.
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After the pressing out and smoothing, the cellulose web
is supplied for residual drying to the drying device. The drying
device preferably can be provided with at least one drying tower.
A plurality of vertical flow nozzles are arranged in this drying
tower. A swing tower for heating or cooling of cellulose web can
follow the at least one drying tower. Thereafter a cooling
tower, can be provided, which ensures that the cellulose web is
cooled to a few degrees under the room temperature before
entering the transverse cutter. Thereby static charging in the
transverse cutter is avoided, which otherwise can lead to a
damage of the vibrating element.
In a second embodiment of the present invention, the
drying device can be provided with a horizontally arranged drying
passage for the cellulose web. Preferably the drying passage can
have three portions, wherein in the first portion the drying with
hot air is performed. The second portion of the drying passage
can be analogous to the swing tower for heating or cooling, while
the last portion can be provided only for cooling of the
cellulose web. Preferably, the drying passage can have an
autonomous web edges control.
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A dancer roll can be arranged between the last smooth
cylinder and the driving device. It compensates a longitudinal
shrinkage of the cellulose web during drying.
For centered orientation of the web tip, a clamping bar
which is electromagnetically fixable on the web tip can be
provided. It can be mounted on two lateral guiding chains.
Moreover, a knockover frame can be provided between the last
smooth cylinder and the drying device. It can have a knockover
rocker which is turnable at both sides by 45° for knocking over
the web tip on approximately 500-1000 mm width. For guiding the
web edges, soft running displacement coulisses can be arranged.
They can be brought from a 45° position to a 90° position
and
have contact switches which, upon reaching the 90° position,
release the discharge of the upper clamping bar strip.
Further advantages are provided when a demagnetizing
track is provided after the last cooling tower together with a
lifting device for the upper clamping strip. The upper clamping
strip can subsequently be transported back before the first
drying tower by a crane for discharge in picking up machines.
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For unloading of the feed press of the transverse
cutter during long machine stoppages or during eventual leaving
the web in the machine, for avoiding a repeated putting on of the
web, advantageously a clamping press can be provided for the full
web width between the last cooling tower and the transverse
cutter.
For facilitating the work of the machine operator, the
cellulose dewatering machine can be provided for example with a
digital measuring and indicating device for the residual moisture
and the temperature of the cellulose webs, at least before the
entrance in the transverse cutter.
The novel features which are considered as
characteristic for the present invention are set forth in
particular in the appended claims. The invention itself,
however, both as to its construction and its method of operation,
together with additional objects and advantages thereof, will be
best understood from the following description of specific
embodiments when read in connection with the accompanying
drawings.
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BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic view of a first embodiment of a
cellulose dewatering machine in accordance with the present
invention;
Figure 2 is a schematic view of a second embodiment of
a cellulose dewatering machine in accordance with the present
invention.
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DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 1 schematically shows a first embodiment of an
inventive cellulose dewatering machine 10 with a sieve dewatering
device 20, a pressing device 30, a driving device 40 and a
subsequent transverse cutter 50.
The sieve dewatering device 20 has a round sieve
cylinder unit with four suction round sieves 21, 22, 23 and 24, a
turning press 25 and a dandy roll press 26. The cellulose web 11
after the first passage through the suction round sieves 24-21 is
supplied to the turning press 25, is turned there, and again is
guided through the suction round sieves 21-24 for dewatering of
the second web side. Then it is further supplied through the
dandy roll press 26 and subsequently to the pressing device 30.
The pressing device 30 has two smooth cylinders 31 and
32. Two suction press rolls 33 and 34 are arranged on the smooth
cylinder 31 for improvement of the dewatering efficiency. In
order to support the subsequent drying, both smooth cylinders 31
and 32 are provided with dryer hoods 35 and 36. The use of two
smooth cylinders 31 and 32 in an S-loop allows the handling of
both sides of the cellulose web 11, so that they are not only
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dewatered but also smooth. Therefore a reliable overlapping of
the sheets on the transverse cutter 50 and thereby speeds 150-160
m/min can be guaranteed.
The pressing device instead of two smooth cylinders,
can also have only one smooth cylinder. In this case, only one
web side is smooth. In some cases this can be sufficient for
obtaining high speeds by allowing an overlapping of the sheets.
From the pressing device 30, the cellulose web 11 is
supplied to the drying device 40. The drying device 40 has a
drying tower 41, a swing tower 42 for heating or cooling, and a
cooling tower 43 for cooling of the cellulose web 11. The drying
in the drying tower 41 is performed by means of vertical flow
nozzles which are not shown in the drawings. The swing tower 42
is used selectively for heating or cooling of the cellulose web
11. The last tower 43 serves exclusively for cooling. The
cellulose web 11 is cooled before the entrance to the transverse
cutter 50 to a few degrees below room temperature to avoid static
charging in the transverse cutter 50. The transverse cutter 50
has in a standard form a reject lock 51 and a changeover switch
52 for bale or staple operation.
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Figure 2 schematically shows a second embodiment of a
cellulose dewatering machine 10' in accordance with the present
invention. It has a sieve dewatering device 20', a pressing
device 30', a drying device 45 and a subsequent transverse cutter
50'. This second embodiment differs from the first embodiment
shown in Figure 1 in that the drying device 45 for the cellulose
web 11' has a horizontally arranged drying passage with three
portions 46, 47 and 48. The first portion 46 is provided for
drying with hot air, the second portion 47 is provided for
heating or cooling, and the third portion 48 is provided for
cooling of the cellulose web 11'.
A cellulose dewatering machine in accordance with the
first embodiment shown in Figure 1 with a working width of for
example 2800 mm and four uses for example 4 x 700 mm width, 1000
mm length, during a staple operation with a staple height of
approximately 1400 mm and a speed of approximately 150 m/min has
a maximum theoretical production of 672000 year tons, in the case
of a continuous operation with 350 working days per year.
In a bail operation with a speed of for example 75
m/min and with a bail height of approximately 500-600 mm, the
production is approximately the half of the above mentioned
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value, while it should be considered that the transverse cutter
is open or in other words operates without overlapping.
During the staple operation with a speed of 150 m/min,
the delivery cycle time is approximately three minutes for each
of four uses. Thereby for example two foil shrinkage heaters can
be provided for staple packing after the device. During bale
operation with a speed of 75 m/min the delivery cycle time is
approximately two minutes. It is completely within the range for
providing for example four bail tying machines with the use of
wire or synthetic plastic.
A conversion of the above described variants from the
bale operation to the staple operation and vice versa is possible
any time without reduction of the speed, by driving on the
transverse cutter on the gaps. The thusly locked sheets are
supplied by the discharge lock into a release vat located
underneath, where it together with the edge strips of the
cellulose web is released by the outer longitudinal cutters and
pumped back into the machine vat.
It is advantageous also when each of the above
described variants can be driven with a dragging application
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construction in the initial time, or in time application breaks
only with the two inner uses to half power.
It will be understood that each of the elements
described above, or two or more together, may also find a useful
application in other types of constructions differing from the
types described above.
While the invention has been illustrated and described
as embodied in cellulose dewatering machine, it is not intended
to be limited to the details shown, since various modifications
and structural changes may be made without departing in any way
from the spirit of the present invention.
Without further analysis, the foregoing will so fully
reveal the gist of the present invention that others can, by
applying current knowledge, readily adapt it for various
applications without omitting features that, from the standpoint
of prior art, fairly constitute essential characteristics of the
generic or specific aspects of this invention.
What is claimed as new and desired to be protected by
Letters Patent is set forth in the appended claims.
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