Note: Descriptions are shown in the official language in which they were submitted.
CA 02551795 2010-11-29
DOUBLE UNWINDER UNIT FOR ROLLS OF SHEET-LIKE MATERIAL
PROVIDED WITH A DEVICE FOR SPLICING THE SHEETS BEING UNWOUND
Field of the Invention
The present invention refers to the field of equipment for unwinding rolls of
sheet-
like material, and particularly paper, tissue paper or the like. To be more
precise, it
concerns a double unwinder unit with a device for splicing the tail end of the
material on a
running out roll with the leading end of the material on a full roll.
Background of the Invention
During the unwinding of rolls of flexible sheet-like material, e.g. paper,
tissue
paper and so on, it becomes necessary to replace run-out rolls with full ones.
Because it is
obviously essential to reduce the down times involved in the roll-changing
procedure, the
known technique involves unwinding equipment capable of completing the
procedure for
setting up a new roll "in the background", using a symmetrical double unwinder
shaft
configuration. In practical terms, while one roll continues to be unwound on
one shaft, the
other shaft is offline and accessible for the installation of a second roll.
When the first roll
becomes run-out, the second unwinder shaft starts to turn, while the run-out
roll can be
replaced with a full one on the first (now offline). Subsequent roll changes
thus take place
on either side in turn, so that a full roll is always readily available.
The double equipment of the type described above is also used to splice the
tail
end of the web on the roll running out to the leading end of the web on the
new roll, so that
the machines downstream of the unwinder (e.g. cutters, rewinders, folding
apparatus, etc.)
are fed with an uninterrupted flow of material, to the evident advantage of
the production
process. In case of paper, splicing is done by overlapping the two edges of
material, the tail
edge of the web on the roll running out and the leading edge of the web on the
new roll,
and compacting the two ends with the aid of a pressure exerted in a direction
normal to the
plane on which the edges lie.
In making the splice, the overlap between the two edges must not be too long,
because this would be a waste of material and might interfere with subsequent
processing
operations. On the other hand, the strength of the splice is directly
proportional to the
longitudinal extension of the overlap, so said length must never drop below a
certain limit.
The tail edge has to be kept in tension when the splice is made, so splicing
has to
be done when there is still a sufficient amount of material remaining to be
unwound from
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the roll. So, together with the splicing action, it becomes necessary to
provide for the
detachment of the spliced end on the near-empty roll from the remainder of the
web beyond
it, by cutting the web crosswise. The cut edge has to be clean and neat, not
only for
aesthetic, but also for functional reasons, since an uneven edge can pose
problems in
subsequent processing stages and related machines. For the same reasons, the
edge on the
leading end of the new roll must be trimmed, again by means of a crosswise
cut, before the
actual splicing process can begin.
For obvious reasons, the splicing procedure needs to be as quick as possible,
so
that it induces a minimal slowdown in the delivery of the material being
unwound. The
splicing device must also be straightforward and structurally compact so as to
avoid it
interfering with the other parts of the equipment or with the material as it
unwinds. The
equipment based on the known technique does not fully satisfy the above-
described
requirements.
Summary of the Invention
Illustrative embodiments may provide a double unwinder unit of the type
previously described, which enables a clean splice of accurately-controllable
longitudinal
extension to be made at the utmost speed, by means of a structurally and
functionally
straightforward splicing device.
In accordance with one illustrative embodiment, there is provided an unwinder
unit for rolls of sheet-like material. The unit includes a pair of unwinder
shafts for
respective rolls, lying on either side of a plane of symmetry of the unit in
order to feed the
material onto the plane of symmetry and beyond the same plane to equipment
arranged
downstream. The unit also includes a device for splicing a tail end of a
running-out roll
unwinding from one of the shafts, to a leading end of a new, full roll
arranged on the other
one of the shafts. The device has a symmetrical configuration with respect to
the plane of
symmetry and includes: a pair of splicing cylinders, arranged on opposite
sides of the plane
of symmetry, revolving around their own respective axes and displaceable close
to and
away from each other, the close position corresponding to a condition of
mutual contact,
with a certain degree of pressure, on the plane of symmetry; drive provisions
for driving
the rotation and the displacement of said cylinders; groups of aligned suction
holes formed
along respective generatrices of the cylinders, for retaining the material on
the cylinders
and deviating it away from the plane of symmetry; in each one of said
cylinders, first
cutting provisions cooperating with the cylinder, downstream of the area of
contact with
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the other one of said cylinders, to transversely cut the material retained on
the cylinder
along a generatrix thereof, and second cutting provisions, arranged upstream,
in turn for
cutting the material transversely; and control provisions for controlling the
drive provisions
in order to synchronize the movement of the cylinders with the speed at which
the material
is unwound from the rolls.
The plane of symmetry may be substantially vertical, and may separate the
unwinder shafts and the splicing cylinders of the splicing device, all of
which may be
arranged with horizontal axes. Deviating provisions may be provided to deviate
the
material in order to feed it into the device from above along the plane of
symmetry, and
then deviate it horizontally downstream of the device below one of the
unwinder shafts.
The first cutting provisions may include, for each cylinder, a first cutter
lying
underneath the cylinder, radially pressing against it along a generatrix
thereof. A deviating
roller may cooperate tangentially with the cylinder to deviate the material
released by the
cylinder downstream of the first cutter away from the plane of symmetry.
Underneath the first cutter and the deviating roller, collector provisions may
be
arranged for collecting the material cut by the first cutter. The collector
provisions may be
removable from the unit.
The second cutting provisions may include, in each cylinder, a second cutter
arranged above the cylinder for cutting the material in cooperation with a
counter-cutting
bar.
The second cutter may be arranged between two rollers of the deviating
provisions, the rollers may include a main roller substantially tangent to the
plane of
symmetry and an auxiliary roller placed upstream, further away from the plane
of
symmetry.
The first and second cutting means may each include a cutting disc mounted
slidingly on a guide extending along the corresponding cutting line of the
material.
The suction holes may communicate with inner axial channels, which may be
open at least at one axial end of the relevant cylinder in order to
communicate with suction
provisions that may be arranged externally. The opening of the channel may be
obstructed
by distributor provisions for timing the suction force in order to control the
retaining/release of the material by the cylinder.
The distributor provisions may include at least one flange arranged at a
shoulder
face of the cylinder, and a distributor passage formed in the flange along an
arc of the
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circular trajectory of said axial channels. The passage may communicate with
the outside
of the flange via a suction inlet for the suction provisions.
A separating screen may lie on the plane of symmetry in order to separate the
two
symmetrical parts of the splicing device above the splicing cylinders.
Working surfaces of the splicing cylinders may be slightly corrugated, so that
longitudinal ridges may be generated in order to reduce the contact surface
area when the
cylinders come into contact with each other.
The second cutting provisions may be mounted according to an adjustably
movable arrangement.
Brief Description of the Drawings
The characteristics and advantages of the double unwinder unit according to
the
present invention for rolls of sheet-like material, provided with a device for
splicing the
rolls being unwound, will be apparent from the following description of its
embodiments,
provided purely as an illustrative and not restrictive example, with reference
to the attached
drawings, wherein:
figure 1 is a schematic front view of the unit according to the invention;
figure 2 is a cross section of the unit along line II-II of figure 1, with
some parts
omitted for the sake of clarity;
figures 3a to 3h show front views, as in figure 1 but enlarged, of the unit's
splicing
device in successive steps of the procedure for splicing the tail end of one
web with the
leading end of another;
figures 4 and 5 respectively show a longitudinal and axial view of a splicing
cylinder of the splicing device according to the previous figures;
figure 6 is an axial view of a pneumatic distributor flange associated with
the
cylinder of figures 4 and 5; and
figure 7 is a cross section of the flange in figure 6, in the plane indicated
by the
line VII-VII.
Detailed Description of the Preferred Embodiment
Referring to figures 1 and 2, a unit according to the invention comprises a
pair of
unwinder shafts lying side by side 1, 2, revolvingly supported at one end by a
frame 3 so
that they lie parallel to one another on a horizontal plane. The rolls B1, B2
of paper web to
be unwound are placed respectively on the shafts 1, 2. The tubes inside the
rolls B1, B2 are
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inserted coaxially onto the shafts 1, 2 from their free end and fixed in place
by means of
known devices.
Equally known is the configuration of the unwinding drive means, represented
in
the case in point by two articulated arms 4, 5, hinged with one end to the
frame 3, around
respective horizontal axes. Each of the two arms 4, 5 comes over a
corresponding shaft 1, 2
with a mirrored position with respect to the unit's vertical plane of
symmetry, indicated by
the letter X.
The structure of the arms 4, 5 is not described in detail, since - as already
mentioned - it is well known and as such falling out of the scope of the
present invention.
Suffice it to say that the material on the rolls 131, B2, is unwound by
tangential contact of
respective driving belts 4a, 5a, extending between sets of idler rollers 4b,
5b (two of which
are motorized, one per belt) supported revolvingly by the arms 4, 5. The
angular
displacement of the latter around the hinged end is controlled by respective
jacks 6, 7.
Clearly, the advantage of this solution is that there is no need to adjust the
turning speed of
the unwinding drive means, to keep a constant delivery rate of the material
being unwound
as the diameter of the roll gradually diminishes.
With particular reference to figure 1, the web of material M being unwound
from
the rolls, departing from them in a tangential direction, is fed towards the
plane of
symmetry X, and particularly towards a cutting and splicing device, globally
indicated by
the numeral 8, also comprising two parts that are mirrored to each other on
either side of
the plane X. The device 8, which will be described in more detail later on, is
placed at a
height slightly lower than the shafts 1, 2, and the web M arrives at its top
end. After passing
through the device 8 while lying on the plane X, and thus sliding vertically,
the sheet M
exits from the bottom of the device and is brought by deviating rollers 9,
into a horizontal
position, near the floor, and thus leaves the unit sideways, heading for the
equipment
downstream in the process.
The core of the device 8 comprises two identical splicing cylinders, indicated
as
11, 12, situated with their horizontal axis at the same height on either side
of the plane of
symmetry X. These cylinders are supported by a frame 10, shown in figure 2, so
that they
can not only turn around their own axis, but also move horizontally so as to
come closer
together or move further apart, the position in which they are closest to each
other
corresponding to a condition of mutual contact with some degree of pressure
(i.e. they
generate the pressure needed to ensure the adhesion of the two ends of web
being spliced)
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on the plane of symmetry X. The mutual contact pressure can be advantageously
increased
by giving the two cylinders a working surface with slight circumferential
corrugations. In
practice, longitudinal ridges are created along the generatrices of the
cylinders so as to give
rise to a smaller contact surface area.
Again with particular reference to figure 2, the means for driving the
rotation of
the cylinders 11, 12 comprise, for instance, respective motors 26, 27
supported by the
frame 3 and engaging with the ends of the cylinders by means of transmissions
28, 29. As
will be explained in more detail hereinafter, these motors 26, 27 are capable
of ensuring the
rotation of the cylinders 11, 12 in synchronism with the speed of the webs
being processed
during the splicing stage. The translatory movement is induced by hydraulic
actuators 30,
incorporated in the frame 10 and engaging in their turn on the ends of the
cylinders 11, 12.
Said drive components are schematically illustrated by way of example, since
they can be
realized using constructions that are obvious to any person skilled in the
art.
The splicing cylinders 11, 12 can retain the paper material M on the working
surface 11a, 12a by means of a vacuum system. In fact, with reference now also
and in
particular to figures 4 to 7, regarding the cylinder 11 (the cylinder 12 being
identical), the
working surface 11a has a distribution of suction holes 113 arranged along a
number of
equally spaced generatrices (four in the example). The passage of a pneumatic
flow is
achieved through channels 114 formed axially in the cylinder, in a off-
centered position, so
that they extend underneath along respective rows of holes 113. The channels
114 are open
at the ends on the two shoulder faces 11b of the cylinder. The corresponding
holes and
channels on the cylinder 12 can be seen, albeit with no numerical reference
for the sake of
clarity, in figure 1 and in figures 3a to 3h, which will be considered later
on.
The suction exerted through the holes 113 in the cylinders 11 and 12 is
suitably
timed, using a system known as such, so that the material M is retained
through a given
angle of rotation, whereas it is released for the remaining angle, according
to the required
control timing. For this purpose, the shoulder faces of the cylinders are
closed between two
fixed timing flanges, one of which is schematically illustrated in figures 6
and 7, indicated
by the numeral 115.
The flange 115, provided with a central hole 115a to allow for the passage of
the
core of the corresponding cylinder 11, intercepts the open ends of the
corresponding
channels 114. Along the circular trajectory defined by said channels, however,
a distributor
passage 115b is formed in the inner face of the flange 115, i.e. the one in
contact with the
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shoulder face of the cylinder. The passage 115b consists of a blind arc-shaped
notch whose
width substantially coincides with the diameter of the channels 114.
An axial passage 115c places the distributor passage 115b in pneumatic
communication with the outside, where a suction inlet (not illustrated) is
arranged. The
distributor passage 115b thus opens the channels on the outside and the
suction action is
only established along a given arc of trajectory, the length of which is thus
determined by
the circumferential extension of the arc-shaped notch. For the remainder of
the arc of
rotation, on the other hand, the channels will be obstructed by the flange
115, so there will
be no suction action.
Returning now to figure 1, the splicing cylinders 11, 12 cooperate with
respective
first cutters 13, 14, arranged underneath the cylinders, and consequently
downstream of the
splicing area. The first cutters 13, 14 are only schematically represented in
figure 1, while
the characteristics that exemplify one of them (i.e. the cutter 13 associated
with the cylinder
11) are shown in more detail in figures 4 and 5. It can be noticed in
particular that the cutter
13 can be realized with a cutting disc 13a mounted slidingly and driven by a
motor (not
shown) on a guide 13b lying along a generatrix of the cylinder 11. Following
the axial
movement of the disc, which comes up against the working surface of the
corresponding
cylinder, the web M is scored and cut along a generatrix corresponding to a
line crosswise
to the web.
Idler rollers 15, 16 cooperating tangentially with the cylinders 11, 12 are
arranged
underneath the cylinders 11, 12 and alongside the first cutters 13, 14,
displaced further
away from the plane of symmetry X. Two boxes 17, 18 for collecting the
material M are
arranged immediately beneath the idler rollers 15, 16.
Upstream of the cylinders 11, 12, i.e. above them, the device 8 is completed
by a
separating screen 19 lying on the plane of symmetry X and by a pair of
deviating rollers 20,
21, that are mirrored to each other and assisted by auxiliary rollers 22, 23,
to deviate the
web M from the plane on which it leaves the corresponding roll to the plane of
symmetry
X. Finally, there are second cutters 24, 25 (referring again to figure 1),
which are operated
to cut the web material M along crosswise cutting lines immediately upstream
of the
deviating rollers 22, 23. The second cutters 24, 25 are entirely similar to
the first cutters 13,
14, except that they cooperate not with the cylinders 11, 12, but with
specific respective
counter-cutting bars 31, 32.
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The unit is controlled by means of a control system that is not illustrated or
described in detail here because its configuration is self-evident, given the
functional
description provided below.
With reference now specifically to figures 3a to 3h, as well as to figure 1,
the unit
according to the present invention works in the following manner. In figure 1,
a roll 131 is
unwinding normally on the shaft 1, with the material M that, as explained
above, passes
through the device 8 to exit sideways underneath it, downstream of the
deviating rollers 9.
The two splicing cylinders 11, 12 are both at a standstill in a withdrawn
position, furthest
away from each other, where they do not interfere with the passing of the
material as it
unwinds. The other shaft 2 is free and accessible for the setup of a full roll
B2, that will
need to be spliced to the roll 131, so that the roll B2 can replace the roll
B1 in the unwinding
process when the latter becomes run-out.
In figure 3a, the roll B2 has thus been set up on the shaft 2 and the leading
end of
the sheet of material M2 has been inserted in the device 8, between the
deviating roller 21
and the separation screen 19, up until the edge of said leading end has been
taken up by the
suction system on the corresponding splicing cylinder 12. In the meantime, the
material MI
unwinding from the roll 131 continues to slide vertically, with the screen 19
that physically
separates the two material feedings, thereby avoiding any risk of interference
between
them.
At this point, via the control system, the splice is prepared by unwinding the
roll
B2 on low speed (figure 3b). In this phase, the drive belt 5a, and
consequently also the web
on the roll B2, obviously move in synchronism with the splicing cylinder 12.
The material
M2 is withheld by the suction force against the cylinder 12 over a certain arc
of rotation,
then it is released to engage with the idler roller 16, according to the
timing established by
the distributors 115b of the fixed flanges 115, and thus unloaded and
collected to a certain
amount in the collection box 18 underneath, until the perfect alignment of the
web is
achieved and any imperfections in the material are eliminated.
Figure 3c shows the very next stage: when the forward feed stops, the cylinder
12
is positioned with the suction holes exactly in phase with the cutter 14,
which has been
used to perform a crosswise cut, thus providing the material M2 with a clean,
neat edge that
is held against the cylinder by the suction holes. The fact that the suction
force, and thus the.
adhesion to the cylinder, takes effect right along said edge enables its
position to be
controlled extremely precisely. The resulting scrap S remains in the box 18,
from where it
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can subsequently be taken away. The cylinder 12, still kept in synchronism
with the
rotation of the roll B2, is turned in reverse, raising back the cut edge of
the end of sheet,
which is still held in place by the suction system, up to the exact height of
the axes of the
cylinders (figure 3d).
During the above-described procedure for preparing the leading end of the roll
B2,
the roll 131 has continued to unwind undisturbed. When it is nearly run out,
as shown in
figure 3e, the unwinding is stopped and the actual splicing step takes place
between the
leading end of the material M2 on the full roll B2, and the material M1 on the
roll 131. The
two splicing cylinders 12 and 13 are moved into mutual contact, where they
generate the
pressure needed to join the two webs of material together.
Now the cutter 24 upstream of the splicing cylinders takes action on the
material
M1 on the roll 131, making a crosswise cut (figure 3f). The tail end of the
sheet on the roll
131 thus also has a clean, neat edge. The splicing cylinders start to turn
again, at a
controlled pace in synchronism with the speed of the full roll B2. The splice
is completed
when the edge of the tail end M1 passes beyond the splicing cylinders (figure
3g). Said
cylinders then move back into the position where they are furthest away from
each other
(figure 3f) and stop turning, thus returning to the initial situation with the
material sliding
smoothly and freely, this time from the full roll B2. The shaft 1 is now ready
for loading a
new roll as soon as the empty tube (with any material left on it) has been
removed.
The whole above-described procedure can be repeated in exactly the same way,
but on opposite sides of the unit. Thanks to the perfectly symmetrical
arrangement of the
unit, and of the splicing device 8 in particular, the leading end of a full
roll will be prepared
alternately on one side and the tail end of the roll running out will be cut
on the other.
The unit according to the present invention primarily enables the longitudinal
extension of the splice to be accurately controlled, since its length is
determined by the
distance, measured along the trajectory of the web, between the splicing
cylinders 11, 12
and one or other of the cutters 24, 25 upstream. According to a possible
embodiment, said
distance may be varied by means of a displaceable mounting of the cutters 24,
25, to adapt
the dimensions of the splice as the case may be.
Another advantage of the unit according to the invention lies in the
opportunity to
realize both the cut edges of the spliced ends with the utmost neatness and
precision, and
thus avoid problems in subsequent processing stages and related machines. In
particular,
the leading end of the full roll can be trimmed with a minimal waste of
material, thanks to
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the preparatory procedure being controlled by the transport induced by the
suction force
exerted by the splicing cylinders 11, 12.
The cutting and splicing procedure also features few, elementary operational
steps,
so it can be done quickly, inducing a scarcely significant slow down in the
feed rate of the
web being unwound. The preparation and cutting of the material, controlled
automatically
by means of the suction system, can cope with even very wide and soft
materials, as may
be necessary particularly in the tissue paper field. Finally, the
straightforward and compact
design of the splicing device makes it very economical, even from the
maintenance
standpoint, and when it is not in use it does not interfere in any way with
the normal
unwinding of the material.
Variations and/or modifications can be made to the double unwinder unit for
rolls
of sheet-like material with a device for splicing the rolls as they unwind
according to the
present invention, without thereby departing from the scope of the invention
itself.
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