Note: Descriptions are shown in the official language in which they were submitted.
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Slitter for a running fibrous web
The invention relates to a slitter for a running
fibrous web having a positioning apparatus which is
assisted by drawing means for at least one cutting
device, preferably a cutting blade or a high-pressure
water-jet cutting head.
Apparatuses of this type are known from the very
different fields in the production or treatment of
fibrous webs, in particular paper or cardboard webs, to
which reference is made in the following text. The
following are to be mentioned:
a) slitting a running web into part webs for separate
winding up, for example to form dispatch reels
which are intended for the printing industry,
b) edge trimming to fix a desired format width and
optionally to cut off side regions which do not
correspond to the quality requirements which are
met in the central region of the web, and
c) cutting strips which are used for a transfer
operation to a following treatment machine,
whereas the rest of the fibrous web is moved into
a reject container, the transfer strip being cut
to the original fibrous web width after successful
transfer.
EP 0433583 is an example for a positioning apparatus
which is assisted by drawing means. This embodiment has
been built multiple times by the applicant. Numerous
knives can be moved and set via a toothed belt, by
being coupled to the belt as required. However, the
control outlay is quite considerable and, in
particular, no longer cost-effective if it is intended
that the cutting device can move to only two or three
fixed positions.
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The invention aims in this direction, however. The
desire is therefore to make it possible for the tasks
of the abovementioned slitting examples according to
items b) and c) to be achieved by way of the invention.
In the prior art, for example, an actuating cylinder
which is arranged laterally next to the paper or
cardboard making machine is used for this purpose. Said
actuating cylinder is defined by its stops in the
cutting position and merely has to be capable of being
loaded with compressed air in two directions. If,
however, the intention is not to sever a transfer strip
at the edge of the fibrous web, but rather, for
example, to cut out a 20 cm wide strip a metre away
from the edge, the stroke of the cylinder already has
to be very large, which leads to the cylinder reaching
undesirably far into the maintenance space next to the
paper or cardboard making machine. If an actuating
motor, for example having a belt drive for the cutting
device, is used instead, a comparatively high control
outlay is to be made again.
The invention is therefore based on the object of
providing a slitter for a running fibrous web, which
slitter can be actuated simply and takes up a small
amount of space laterally next to the running fibrous
web.
The slitter of the invention achieves this object by,
in order to realize at least one movement direction of
the cutting device, the positioning apparatus which is
assisted by drawing means having at least one fixed
deflection roller and at least one floating deflection
roller for the drawing means.
Therefore, an apparatus is formed which is similar to a
block and tackle and permits a great step-up ratio.
However, the power step-up ratio is not used in this
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case, as is customary in blocks and tackles, but rather
the travel step-up ratio. A short travel of a drive
unit makes it possible for the cutting device to move
to the desired cutting or parked position. Here, the
entire device is of very small overall size to the side
of the paper web, even if the travel of the cutting
element is great. A short stroke of the drawing means
brings about a relatively long movement travel of the
cutting device. Cables, flat belts and V-belts and, in
particular, toothed belts are suitable, on account of
slip-free force transmission, as suitable drawing
means.
Knives are suitable as cutting devices. However, after
they have been moved into the working (= cutting)
position, they still have to be set in the direction of
the web. A high-pressure water-jet cutting device is
therefore preferably used in this invention. On account
of the space-saving embodiment of the positioning
device, it is possible without problems to allow the
web to run over a cutting table and to catch the water
jet in suitable discharge pipes, as is known from
EP0870583 Bl, for example.
Since the drawing means cannot also be used as a rule
as pressure means, it is advantageous if, in order to
realize two movement directions of the cutting device,
the positioning apparatus which is assisted by drawing
means has in each case at least one fixed deflection
roller and at least one floating deflection roller for
the drawing means. Since these two units are arranged
with in each case at least one fixed and one floating
deflection roller in parallel next to one another, they
do not take up any additional space. As an alternative,
however, it is also conceivable to realize one of the
movement directions via a spring element.
It has been shown in tests that, in order to realize
two movement directions of the cutting device, the
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positioning apparatus which is assisted by drawing
means has a fixed deflection roller and two floating
deflection rollers for the drawing means. In an
embodiment of this type, a satisfactory compromise is
found which firstly permits a quadruple travel step-up
ratio and secondly uses sufficiently little
installation space. If only one movement direction is
covered by the positioning apparatus, the opposite
movement can be carried out by a spring element again.
In order to secure functionality, it is advantageously
ensured that the positioning apparatus which is
assisted by drawing means has at least one linear
drive. In turn, a linear drive which is formed by a
cylinder/piston unit is preferably selected by said
linear drives. The movement direction of the linear
drive can be arranged in a space-saving manner parallel
to the movement direction of the cutting element. The
slitter is of very small overall design if the linear
drive is actually arranged parallel to the movement
path of the cutting element.
If, for example, the width of the strip to be cut off
varies, it is advantageous if, in addition to the
parked position, two different working (= cutting)
positions can be assumed. This is achieved without
great outlay on control and regulating technology by
the cylinder/piston unit being of multiple-stage
configuration, in particular as a three-position
cylinder.
It is advantageously ensured if the linear drive is
designed in such a way that it acts on a holder, to
which at least one floating deflection roller for the
drawing means is attached. In this way, the actuating
travel of the drive acts precisely on the floating
deflection roller, around which the drawing means is
wrapped. A step-up ratio with regard to the travel
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which can be four times or even greater there results
at the cutting element, to which one drawing-means end
is fastened which is either the same drawing means or a
further drawing means (as in the case of a power block
5 and tackle or a differential block and tackle).
A guide is preferably provided on a crossmember for the
cutting device or for a carriage which carries said
cutting device. The guide ensures that the spacing from
the running fibrous web is secured during the movement.
The crossmember is particularly configured here as a
box. This prevents dust or dirt being able to pass onto
the guide, and the cutting head is protected largely
against tearing fibrous webs.
The linear drive is advantageously integrated into the
box. The entire slitter then forms a largely (apart
from the passage of the cutting element) closed and
compact structural unit. It can be fastened as one unit
rapidly to any location of the paper or cardboard
making machine. In the event of a possible failure of
the cleaning apparatus (for example, clogging of the
water-jet nozzle), a complete unit can be exchanged
quickly, with the result that production down times do
not occur in the paper or cardboard making machine.
In the following text, the invention will be explained
using exemplary embodiments with reference to the
drawings, in which:
Figure 1 shows a sectioned illustration of a slitter
according to the invention with a
crossmember, and
Figure 2, Figure 3 and Figure 4 show the positioning
device of the slitter according to the
invention with three different positions of
the cutting device without a crossmember.
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Fig. 1 shows the slitter 1 according to the invention
in cross section. The slitter 1 is provided with a
cutting device 2 which is formed in this exemplary
embodiment substantially by a high-pressure water-jet
nozzle 3. The water jet which emerges from said high-
pressure water-jet nozzle 3 is capable of cutting a
running fibrous web (not shown), preferably a paper or
cardboard web. As an alternative, however, an
optionally rotating knife or any other form of cutting
device can also be used here.
The cutting device 2 is connected to a carriage 5 via a
cutting-device holder 4. The carriage 5 can be moved in
a guide 7 (into the sheet plane in Figure 1) . To this
end, said carriage 5 is provided with running rollers 6
which run in rails 7a. Said rails 7a are fastened to a
crossmember 8 which is advantageously configured in the
form of an almost closed box 9. As a result, the guide
7 is largely protected against dust deposits.
A linear drive 10, in particular a cylinder/piston unit
10a, which is connected to the crossmember 8 via a
holder 11 serves as drive for the carriage 5. It is
also accommodated within the box 9 in a protected
manner. The cylinder/piston unit 10a exerts a force on
a drawing means 12 which in turn acts on the carriage.
Here, the drawing means wraps around at least one fixed
deflection roller 13 and one floating deflection roller
14. In the concrete case, the drawing means is
accordingly connected like a block and tackle, in
particular like a power block and tackle or a
differential block and tackle.
The positioning device 18 of the cutting device 2 and
its method of operation are clarified in Figures 2 to
4. Here, for the sake of clarity, the cutting device 2
itself and the crossmember 8 are not shown in the
drawing. Figure 2 shows the carriage 5 for the cutting
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device 2 in a first cutting position A and Figure 4
shows the carriage in its parked position P. As a
result of the fact that the cylinder/piston unit 10a in
the exemplary embodiment has three positions, there is
an additional second cutting position B which is shown
in Figure 3.
There is one fixed deflection roller 13v, 13r and two
floating deflection rollers 14v, 14r, 15v, 15r for each
movement direction of the carriage 5. Here, the indices
v and r are intended to indicate the movement
direction, for which the respective deflection roller
is significant. v indicates the movement direction to
the first cutting position A and r indicates the
movement direction to the parked position P. For each
movement direction, two drawing means 12 are also
provided which bear the reference numerals 12v, 12v'
and 12r, 12r' analogously to the deflection rollers 13,
14.
The piston 17 of the cylinder/piston unit 10a acts via
a connecting plate 16 directly on two floating
deflecting rollers 15v, 15r which are fastened to the
latter. Depending on the movement direction of the
piston 17, one of the drawing means 12v' or 12r' is
subjected to a tensile load. As the piston moves, the
spacing changes between the floating deflection rollers
14v, 14r and 15v, 15r, the carriage moving with a
travel step-up ratio of 4:1, which carriage is
connected to the second drawing means 12v, 12r which
wraps around the respective second floating deflection
roller 14v, 14r.
The entire arrangement of the slitter 1 according to
the invention including the positioning device 18 is of
extraordinarily compact overall design and can be
accommodated comfortably in the available installation
space, without protruding too far laterally next to the
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paper or cardboard making machine. No outlay is to be
made on control technology to position the cutting
device 2 at the desired location, apart from a
compressed-air supply which can be switched on and off
via the compressed-air connections 19.
The embodiments shown can be deviated from in many
regards, without departing from the basic concept of
the invention. In particular, the number and diameter
of fixed and floating deflection rollers (13, 14, 15)
can vary and can be adapted to the required conditions.
A spring element can also be used instead of one of the
drawing means 12. Not only cables but also, for
example, V-belts or toothed belts can be used as
drawing means.
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List of Reference Numerals
1 Slitter
2 Cutting device
3 High-pressure water-jet nozzle
4 Cutting-device holder
Carriage
6 Running roller
7 Guide
7a Rail
8 Crossmember
9 Box
Linear drive
l0a Cylinder/piston unit
11 Holder
12 Drawing means
12v, 12v' Drawing means for the movement to the
cutting position
12r, 12r' Drawing means for the movement to the
parked position
13, 13v, 13r Fixed deflection roller
14, 14v, 14r Floating deflection roller
15, 15v, 15r Floating deflection roller
16 Connecting plate
17 Piston
18 Positioning device
19 Compressed-air connection
A First cutting position
B Second cutting position
P Parked position
