Note: Descriptions are shown in the official language in which they were submitted.
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"REWINDING MACHINE AND METHOD FOR PRODUCING LOGS OF WEB
MATERIAL"
DESCRIPTION
Technical Field
The present invention relates to methods and machines for producing logs of
web material, in particular but not exclusively logs of paper, in particular
tissue pa-
per, for example rolls of toilet tissue, kitchen towels or the like.
State of the art
In the field of paper manufacturing, in particular for the production of rolls
of
toilet tissue, kitchen towels or the like, large reels (parent reels) of
tissue paper com-
ing directly from the continuous production machine are wound. These large
reels are
subsequently unwound and rewound to produce rolls or logs with smaller
diameters,
corresponding to the diameters of the end product destined for the market.
These logs
have an axial length equal to a multiple of the finished roll destined for
distribution
and for sale and are subsequently cut by cutting machines to obtain the end
product
destined to be packaged and subsequently marketed.
To produce logs of web material, modern rewinding machines provide for the
use of winding rollers that, in various combinations and arrangements, and
with suit-
ably controlled rotation, allow logs to be produced automatically in rapid
sequence
through continuous feed of the web material. At the end of winding of a log,
the log
must be moved away from the winding area and the web material must be severed
(by cutting, tearing or the like), to allow winding of a subsequent log to
start. Nor-
mally, winding takes place around winding cores, typically but not exclusively
made
of cardboard, plastic or another similar suitable material. In some cases,
winding
takes place around extractable and recyclable mandrels, i.e. which are
extracted from
the completed log after winding has been completed, to be reinserted into the
rewind-
ing machine in order to wind a subsequent log.
In winding machines of more modern design, the winding movement is im-
parted to the logs being formed by means of contact with two or more rollers
rotating
at controlled speed. These rewinding machines are called peripheral or surface
re-
winding machines, as the winding movement is imparted peripherally through the
contact between the surface of the winding rollers and the surface of the logs
being
formed. Examples of automatic continuous surface rewinding machines of this
type
are disclosed in US patent n. 5,979,818 and in other patents of the same
family, and
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in the patent literature cited in this patent. An improvement to the machine
described
in this US patent is described in WO-A-2011/104737 and in W02007/083336. In
these prior art winding machines, severing of the web material is performed by
means of a severing, tearing or cutting member, which cooperates with a fixed
axis
winding roller, around which the web material is fed, and which defines,
together
with a second winding roller, a nip for inserting the winding cores into a
winding
cradle.
These machines are also defined as continuous and automatic, as the various
steps of the winding cycle of each log follow one another automatically,
passing from
the production of one log to the next, without interrupting the feed of the
web materi-
al and at an approximately constant or substantially constant speed. The term
auto-
matic continuous rewinding machine is used in the present description and in
the ap-
pended claims to indicate this type of machine.
One of the critical steps in automatic continuous peripheral rewinding ma-
chines of the type described above consists in the change-over step, i.e. the
step of
severing the web material, discharging the completed log and starting to wind
a new
log around a new winding core inserted into the winding cradle.
Various solutions have been studied to perform these operations automatically
and rapidly, for example through the use of winding rollers rotating at
controlled
speed that accelerate and/or decelerate in synchronism in order to favor
correct
movement of the completed logs and of the new cores. In some cases, tearing
sys-
tems are provided, in which the web material is severed at the end of winding
by
means of a difference in speed. In other cases, pressurized air systems,
suction sys-
tems, mechanical systems or the like are used to perform severing of the web
materi-
al.
WO-A-2012/042549 describes a peripheral automatic rewinding machine
with four rollers. The use of four rollers, all or at least some with movable
axes, al-
lows two winding cradles to be defined and more efficient control of the log
being
formed. In some embodiments described in that document, the log being formed
is
always in contact with at least three winding rollers and in some cases it can
be tem-
porarily in contact with four winding rollers. This allows particularly
efficient control
of the winding cycle, of the shape of the log and of the winding density to be
ob-
tained. In some embodiments the web material is severed by lengthening the
path of
the web material between two winding rollers. Lengthening causes the web
material
to break, forming the free trailing edge of a complete log and a free leading
edge to
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start winding the subsequent log on a new core. Although this machine achieves
par-
ticularly appreciable results in terms of winding accuracy and operating
reliability,
there are some aspects that could be further improved. In particular, correct
operation
and reproducibility of the winding cycle in some cases can depend on the
properties
of the material being processed, i.e. of the web material and/or of the
winding cores.
SUMMARY OF THE INVENTION
According to the present disclosure, there is provided a rewinding machine
with four rollers, of automatic continuous peripheral type, in which logs of
web ma-
terial are wound in rapid sequence around winding cores, without interrupting
the
feed of the web material, i.e. feeding the web material continuously or
substantially
continuously to a winding head, which comprises, in addition to the winding
rollers,
also a mechanism for severing of the web material at the end of each winding
cycle.
By continuous or substantially continuous feed it is intended here that the
web
material has a feed speed that is substantially independent from the winding
cycle, it
being understood that other factors can, even substantially, modify the feed
speed of
the web material. For example, when a parent reel from which the web material
is
dispensed, must be replaced, or when the web material breaks, it may be
necessary to
slow or even stop feed of the web material to the winding head. However, this
varia-
tion of speed or stop is not correlated to the winding cycle of the single
logs.
According to one aspect, an automatic continuous peripheral rewinding ma-
chine for producing logs of web material wound around winding cores is
provided,
comprising a first winding cradle formed between a first winding roller, a
second
winding roller and a third winding roller. The first winding roller and the
second
winding roller define a nip through which the winding cores with the web
material
wound around them pass. The rewinding machine can also comprise a winding
cores
feed path that extends between the first winding roller and the third winding
roller.
Advantageously, a second winding cradle is also provided, formed between the
first
winding roller, the second winding roller and a fourth winding roller. The
third wind-
ing roller is positioned upstream of the nip and the fourth winding roller is
positioned
downstream of the nip, with respect to the direction of feed of the winding
cores
through the nip. The rewinding machine can comprise a rolling surface for the
wind-
ing cores, extending partially around the first winding roller toward the
third winding
roller. Between the rolling surface and the first winding roller an insertion,
i.e. feed,
channel for the winding cores is defined. In the rewinding machine there can
be de-
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fined a feed path for the web material which extends between the first winding
roller
and the third winding roller and between the first winding roller and the
second
winding roller. The rolling surface is configured and arranged with respect to
the first
winding roller so that the cores are fed by rolling in contact with the
rolling surface
and with the web material driven around the first winding roller.
In the context of the present description and of the appended claims, coherent-
ly with the meaning given to this term in the field of converting of paper and
other
endless web materials, and in particular according to the terminology of
rewinding
machine manufacturers, the term winding roller is intended as a motorized
roller, i.e.
a roller which is rotated positively by means of a motor, to transmit the
winding
movement to the log being formed by friction between the surface of the
winding
roller and the log, which contacts said winding roller.
The arrangement of the winding rollers is such as to allow, for example,
winding of the logs of web material by co-action always of three winding
rollers in
contact with the log being formed. Moreover, the particular arrangement of the
third
winding roller with respect to the insertion path of the cores and of the web
material,
which extends between the third winding roller and the first winding roller,
as well as
through the nip between the first winding roller and the second winding
roller, which
separates the first winding cradle with respect to the second winding cradle,
can al-
low the winding rollers to be suitably dimensioned, to process also winding
cores of
small diameter.
In advantageous embodiments, the rewinding machine comprises a web mate-
rial severing member configured and controlled to sever the web material at
the end
of winding of a log in the second winding cradle. For example, the severing
member
can be configured and controlled to cooperate with the first winding roller.
In some embodiments, the severing member is configured and controlled to
pinch the web material against the first winding roller and sever the web
material by
generating in the web material a tension greater than the breaking point of
the web
material.
In some embodiments, the rolling surface extends from an inlet of winding
cores feed channel to the third winding roller. In this way, the winding cores
are in-
serted in the channel, fed by rolling along said channel and around the first
winding
roller, with the web material between the first winding roller and the winding
core
being fed in the channel. The path of the winding cores then continues, beyond
the
insertion channel, between the first winding roller and the third winding
roller, to
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reach the first winding cradle.
In advantageous embodiments, the rolling surface has interruptions through
which a severing member can penetrate the winding cores feed channel to pinch
the
web material against the first winding roller. For example, the rolling
surface can be
formed by a comb structure, comprising a plurality of shaped laminar elements,
spaced from one another. The shaped edges of the laminar elements form the
rolling
surface for the cores. The space between adjacent elements allows the passage
of the
severing member. The severing member can comprise one or more pressers that
are
interposed between laminar elements of the comb structure forming the rolling
sur-
face.
In some embodiments, the rolling surface can be divided into two portions. A
first portion can be stationary with respect to a load-bearing structure. A
second por-
tion, positioned downstream of the first portion with respect to the direction
of feed
of the winding cores along the insertion channel, can be movable together with
the
third winding roller.
In possible embodiments, at least one of said first winding roller and second
winding roller has a movable axis, to control the distance between the first
winding
roller and the second winding roller and the dimension of the nip between the
first
winding roller and the second winding roller. In some embodiments, preferably
both
the first winding roller and the second winding roller have a movable axis.
The first
winding roller and the second winding roller can have axes that move
symmetrically
with respect to a centerline plane passing through the nip formed between the
first
winding roller and the second winding roller.
In other embodiments the first winding roller can have a stationary axis while
the second winding roller has a movable axis to control the dimension of the
nip be-
tween the first winding roller and the second winding roller.
The diameters of the four winding rollers could be different from one another.
Preferably, it is advantageous for the first winding roller to have a diameter
larger
than the second winding roller.
In some embodiments the movement of the first, second, third and fourth
winding rollers during forming of the log is controlled so that: a first part
of winding
of the log takes place with the log in contact with the first winding roller,
the second
winding roller and the third winding roller; a second part of winding of the
log takes
place with the log in contact with the first winding roller, the second
winding roller,
the third winding roller and the fourth winding roller; a third part of
winding of the
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log takes place with the log in contact with the first winding roller, the
second wind-
ing roller and the fourth winding roller.
According to a further aspect, there is provided a method for winding a web
material and forming in sequence logs of said web material wound around
winding
cores, comprising the steps of:
arranging four winding rollers defining a first winding cradle between a first
winding roller, a second winding roller and a third winding roller, and a
second wind-
ing cradle between said first winding roller, the second winding roller and a
fourth
winding roller;
arranging a rolling surface extending around the first winding roller and form-
ing therewith a feed channel for the winding cores;
feeding the web material around the first winding roller;
inserting a first winding core into the feed channel and feeding said first
winding core along an insertion path between the first winding roller and the
third
winding roller and inserting the first winding core into the first winding
cradle;
carrying out a first part of a winding cycle of a first log around a first
winding
core in the first winding cradle,
transferring the first log being formed from the first winding cradle into the
second winding cradle through a nip defined between the first winding roller
and the
second winding roller;
carrying out a second part of a winding cycle of the first log in the second
winding cradle;
at the end of winding of the first log in the second winding cradle, inserting
a
second winding core into the feed channel and along the insertion path that
extends
between the first winding roller and the third winding roller and inserting
the second
winding core into the first winding cradle.
In some embodiments, the method can comprise the steps of inserting the
second winding core against the first winding roller pinching the web material
be-
tween the second winding core and the first winding roller, and severing the
web ma-
terial between the first log in the second winding cradle and the second
winding core.
The method can comprise the steps of: providing a web material severing
member; and acting through said severing member on the web material to sever
the
web material thus generating a trailing edge of the first log and a leading
edge with
which to start winding a second log around the second winding core. The two
edges
can be generated between the second core and the first log nearing completion
of
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winding.
In some embodiments, the method can comprise one or more of the following
steps of: arranging the rolling surface around the first winding roller,
defining an in-
sertion channel for the winding cores between the first winding roller and the
rolling
surface, the rolling surface extending from an inlet of the insertion channel
for the
winding cores to the third winding roller; inserting the second winding core
into the
insertion channel and feeding the second winding core by rolling along the
insertion
channel, in contact with the rolling surface and with the web material driven
around
the first winding roller, until reaching the third winding roller; passing the
second
winding core between the first winding roller and the third winding roller;
inserting
the second winding core, with a second log being wound there around, into the
first
winding cradle.
A possible embodiment of the method according to the invention provides for
the following steps:
a) inserting a
first winding core toward the first winding cradle, in con-
tact with the web material entrained around the first winding roller and in
contact
with the rolling surface;
b) fastening a leading edge of the web material to the first winding core;
c) winding a part of a log of web material maintaining the first winding
core in the first winding cradle, and feeding the first winding core toward
the second
winding cradle;
d) passing the first winding core, with the log being wound there around,
through the nip between the first winding roller and the second winding roller
and
transferring the first winding core with the log being formed there around
into the
second winding cradle and completing winding of the log of web material in
said
second winding cradle;
e) inserting a second winding core toward the first winding cradle, in
contact with the web material entrained around the first winding roller and
with the
rolling surface;
0 severing the
web material forming a leading edge of web material, by
means of the severing member and discharging the log of web material from the
sec-
ond winding cradle;
g)
repeating steps (b) to (f) to form a further log around said second
winding core, without interrupting the feed of the web material.
A further embodiment of the method according to the invention can comprise
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the following steps:
a) arranging the third winding roller in an initial position for receiving
a
first winding core;
b) bringing a first winding core into contact with the web material guided
around the first winding roller and angularly accelerating the first winding
core mov-
ing it toward the first winding cradle;
c) fastening a leading edge of the web material to the first winding core;
d) feeding the first winding core between the first winding roller and the
third winding roller into the first winding cradle and winding a part of a log
of web
material maintaining the first winding core in the first winding cradle, and
feeding
the first winding core toward the second winding cradle;
e) passing the first winding core, with the log being wound there around,
through the nip between the first winding roller and the second winding
roller, the
third winding roller moving from the initial position toward the nip between
the first
winding roller and the second winding roller following the log being formed
and in
movement in the first winding cradle and toward the second winding cradle;
0
transferring the first winding core with the log being formed there
around into the second winding cradle
g) completing winding of the log of web material in the second winding
cradle;
h) returning the third winding roller to the initial position;
i) bringing a second winding core into contact with the web material en-
trained around the first winding roller;
j) severing the web material forming a leading edge of web material, by
means of the severing member with the third winding roller in the initial
position,
and discharging the log of web material from the second winding cradle;
k) repeating the steps (c) to (j) to form a further log around said second
winding core, without interrupting the feed of the web material.
In yet a further embodiment, the method can comprise the steps of:
arranging the rolling surface around the first winding roller, forming with
the
first winding roller the feed channel of the winding cores;
at the end of winding of a log, inserting a new winding core into the feed
channel in contact with the rolling surface and with the web material
entrained
around the first winding roller, angularly accelerating the winding core in
the feed
channel;
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inserting the severing member into the feed channel, downstream of the new
winding core, causing breaking of the web material between the new winding
core
and the log nearing completion of winding in the second winding cradle.
Brief Description of Drawings
The invention will be better understood by following the description and ac-
companying drawing, which shows non-limiting practical embodiments of the
inven-
tion. More specifically, in the drawing: le
Figs.1 to 5 schematically show a first embodiment of a rewinding machine
according to the invention in an operating sequence;
Fig.6 shows a diagram of a system of motorized centers for guiding the wind-
ing cores;
Fig.7 shows a sectional view according to the line VII-VII of Fig.6;
Fig.8 shows the position of the system of Figs.6 and 7 with respect to the
cluster of the winding rollers; and
Fig.9 shows a further embodiment of a rewinding machine according to the
present disclosure.
Detailed description of embodiments
Figs.1 to 5 show an embodiment of a continuous peripheral rewinding ma-
chine according to the invention and an operating sequence that shows in
particular
the change-over step, i.e. the step of discharging a log, winding whereof has
been
completed, and inserting a new winding core to start formation of a subsequent
log.
Figs.1 to 5 show the main elements of the rewinding machine, limited to
those necessary to understand the concepts on which the invention is based and
an
operating mode of the machine. Construction details, auxiliary units and
further
components, known and/or that can be designed according to the prior art, are
not
shown in the drawing or described in greater detail. Those skilled in the art
may pro-
vide these further components on the basis of their experience and knowledge
of the
field of paper converting machinery.
In brief, in the embodiment shown herein, the machine, indicated as a whole
with 2, comprises a first winding roller 1 with a rotation axis 1A, arranged
side by
side with a second winding roller 3 having a rotation axis 3A. The axes 1A and
3A
are substantially parallel to each other. Between the two winding rollers 1
and 3 there
is defined a nip 5, through which there is fed (at least during a part of the
winding cy-
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cle of each log) a web material N to be wound around winding cores Al, A2
around
which logs Ll, L2 are formed. The path of the web material N extends around
the
first winding roller 1, wrapping it partially, so that the web material N is
in contact
with the cylindrical surface of the winding roller 1 for a certain arc of
contact, which
can vary during the winding cycle, as will be apparent from the description of
the
winding process.
As will be apparent from the description herein below, the winding cores also
pass through the winding nip 5 during an intermediate step of the winding
cycle.
The winding cores Al, A2 are inserted into the machine upstream of the nip
5, into a first winding cradle 6, formed by the first winding roller 1, by the
second
winding roller 3 and by a third winding roller 7. The reference 7A indicates
the rota-
tion axis of the third winding roller 7, substantially parallel to the axes lA
and 3A of
the first winding roller 1 and of the second winding roller 3, respectively.
Winding of web material N around the winding cores ends when the winding
cores are located in a second winding cradle 10 positioned downstream of the
nip 5
with respect to the direction of feed of the winding cores in the winding head
formed
by the winding rollers. The second winding cradle is formed by the first
winding roll-
er 1, by the second winding roller 3, and by a fourth winding roller 8. The
reference
8A indicates the rotation axis of the fourth winding roller 8, which is
substantially
parallel to the axes of the winding rollers 1, 3, 7. The reference 12
indicates a pair of
arms pivoted in 12A, which support the fourth winding roller 8. The double
arrow
f12 indicates the pivoting movement, i.e. the reciprocating rotation movement
of the
arm 12 and consequently of the fourth winding roller 8. By moving around the
ful-
crum 12A the winding roller 8 can move toward or away from the nip 5 defined
be-
tween the first winding roller 1 and the second winding roller 3.
In other embodiments, the fourth winding roller 8 can be carried by a system
of slides moving on linear guides, instead of by arms pivoted around a
pivoting axis.
Also in this case, the translation movement along the linear guides allows the
wind-
ing roller 8 to move toward and away from the nip 5.
In the present description and in the appended claims, the definition "up-
stream" and "downstream" in relation to the position of the winding rollers
refers to
the direction of feed of the web material and of the axis of the winding
cores, unless
otherwise specified.
The third winding roller 7 is provided with a movement toward and away
from the winding nip 5. For this purpose, in some embodiments the third
winding
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roller 7 is supported by a pair of arms 9 pivoted about an axis 9A to
oscillate, i.e. ro-
tate with a reciprocating motion, according to the double arrow f9. In other
embodi-
ments, not shown, the third winding roller 7 can be supported by slides moving
on
linear guides, so as to follow, for example, a trajectory of rectilinear
motion.
Upstream of the winding nip 5, of the first winding roller 1 and of the second
winding roller 3, a core feeder or inserter 11 is arranged, which can be made
in any
suitable manner and inserts single winding cores Al, A2 toward the first
winding
cradle, as will be described in greater detail with reference to the sequence
of Figs. 1
to 5.
The winding cores can come from a "corewinder", i.e. from a machine for
forming winding cores, associated with the converting line of the web material
N in
which the rewinding machine 2 is inserted, and not shown.
In some embodiments, the rewinding machine comprises a rolling surface 19
for the winding cores. The rolling surface 19 can have a roughly cylindrical
shape,
approximately coaxial to the first winding roller 1 with movable axis, when
this is in
the position of Fig. 1. The rolling surface 19 can have a step 19G in an
intermediate
position of its extension. The rolling surface 19 can be divided into a first
portion
19A and into a second portion 19B, the first positioned upstream of the
second, with
respect to the direction of feed of the web material N.
The rolling surface 19 and the cylindrical surface of the first winding roller
1
form a feed channel 21 for the winding cores Al, A2. When the first winding
roller 1
is in the position of Figs.1 to 4, the height of the feed channel 21 for the
winding
cores can be smaller in the first portion of the feed channel and larger in
the second
portion of the feed channel 21. The purpose of this variation of the height of
the feed
channel 21 is to facilitate the start of a rolling motion of each new winding
core Al,
A2, inserted in the feed channel 21 by the inserter or feeder 11, as will be
explained
herein below. In particular, in the first portion of the feed channel 21, the
height of
the feed channel, i.e. the distance between winding roller 1 and rolling
surface 19,
can be smaller than the diameter of the winding cores Al, A2.
In some embodiments, the rolling surface 19 is formed by a comb structure,
with a plurality of arched plates arranged side-by-side with one another,
between
which free spaces are formed. Through these free spaces between adjacent
plates
forming the rolling surface 19 there can be inserted a severing member of the
web
material N, indicated as a whole with 23. In some embodiments, the comb
structure
forms the first part 19A of the rolling surface and can be stationary, i.e.
fixed with re-
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spect to a supporting structure, not shown. In some embodiments, a second part
19B
of the rolling surface can be formed by elements 19C that move with the axis
7A of
the third winding roller 7, following the movement of this latter.
The elements 19C can also be plates forming a comb structure.
In other embodiments, the surface 19B can be formed by a single arched
plate, which extends transversely with respect to the feed movement of the web
mate-
rial, i.e. parallel to the axes of the winding rollers 1, 3, 7.
In some embodiments, the severing member 23 comprises a presser, for ex-
ample including a plurality of presser members 24. The severing member 23 can
be
provided with a reciprocating rotational movement, about an axis 23A,
approximate-
ly parallel to the axes of the winding rollers 1, 3. Reference f23 indicates
the move-
ment of the severing member 23. Each presser member can have a pressing pad
24A.
The pressing pad 24A can be made, for example, of elastically yielding
material pref-
erably with a high coefficient of friction, for example rubber.
In a manner synchronized with the movement of the other members of the
machine, as will be better illustrated herein below with reference to an
operating cy-
cle, the severing member 23 is pressed against the first winding roller 1 to
pinch the
web material N between the pads 24A of the presser members 24 and the surface
of
the first winding roller 1. This latter can have a surface with annular bands
having a
high coefficient of friction and annular bands having a low coefficient of
friction. In
this context, the terms "high" and "low" are intended to indicate a relative
value of
the coefficients of friction of the two series of alternating annular bands.
The bands
with low coefficient of friction can advantageously be arranged in the areas
in which
the pads 24A of the presser members 24 press. In this way, when the web
material N
is pinched against the first winding roller 1 by the presser members 24, it
tends to be
stopped by the pads 24A and to slide on the annular bands with low coefficient
of
friction of the first winding roller 1.
Fig.1 shows a final step of the winding cycle of a first log Li. As shown in
Fig.1, during this step of the winding cycle of a first log Li around a first
winding
core Al the log Li is located in the second winding cradle 10, in contact with
the
first winding roller 1, the second winding roller 3 and the fourth winding
roller 8.
The web material N is fed, according to the arrow fN around the first winding
roller
1, through the nip 5 between the first winding roller 1 and the second winding
roller
3 and is wound on the log Li being formed, which is rotated by the rollers 1,
3 and 8
and retained thereby in the winding cradle 10. Reference 27 indicates a guide
roller
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for the web material N positioned upstream of the winding head defined by the
wind-
ing rollers 1, 3, 7 and 8.
Preferably, the feed speed of the web material N is substantially constant.
Substantially constant is intended as a speed that varies slowly with respect
to the
winding speed and as a consequence of factors that are independent from the
opera-
tions performed by the members of the winding head described above, which are
controlled so as to perform the winding cycle, discharge the formed log,
insert the
new core and start winding a new log at a constant feed speed of the web
material
toward the cluster of winding rollers and in particular toward the first
winding roller
1.
Durante winding of the log Li, outside the change-over step, which forms a
transitional step in the operation of the machine, the peripheral speeds of
the winding
rollers 1, 3, 7 and 8 are substantially the same as one another and the
various winding
rollers all rotate in the same direction, as indicated by the arrows in the
drawing. In
this case, substantially the same means that the speed can vary limited to the
needs to
control the compactness of winding and the tension of the web material N
between
the winding roller 7 and the winding roller 8, for example to offset the
variation in
tension that could be caused by the movement of the center of the log being
formed
along the path between the winding rollers.
In some embodiments, this difference between peripheral speeds of the wind-
ing rollers can typically be comprised between 0.1 and 1% and preferably
between
0.15 and 0.5%, for example between 0.2 and 0.3%, it being understood that
these
values are examples and are not limiting.
Moreover, the peripheral speeds can vary slightly to cause the advancing
movement of the log being formed, as clarified below, in order for it to pass
from the
first winding cradle 6 to the second winding cradle 10.
The winding cycle of the logs is as follows.
In Fig.1 the log Li in the winding cradle 10 formed by the rollers 1, 3, 8 has
practically been completed, with winding of the required amount of web
material N
around the first winding core Al. The quantity of wound web material can be
deter-
mined by a winding length. A second winding core A2 has been brought by the
wind-
ing cores feeder or inserter 11 at the inlet of the feed channel 21.
The reference C indicates a continuous line or a series of dots of glue
applied
to the outer surface of the second winding core A2.
Fig.2 shows the start of the change-over step, i.e. of discharge of the
complet-
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ed log Li and insertion of the new winding core A2 into the winding head
formed by
the rollers 1, 3, 7, 8.
The second winding core A2 is inserted by the winding cores feeder or insert-
er 11 into the inlet of the feed channel 21 defined between the first winding
roller 1
and the rolling surface 19.
The position of the first winding roller 1 in this step of the winding cycle
is
such that it is about coaxial to the generally and approximately cylindrical
rolling sur-
face 19. The distance between the portion 19A of the rolling surface 19 and
the cy-
lindrical surface of the first winding roller 1 is slightly less than the
diameter of the
winding core A2. In this way, the winding core A2 entering the feed channel 21
is
pressed against the rolling surface 19 and against the web material N driven
around
the first winding roller 1.
This pressure generates a friction force between the surface of the winding
core A2 and the rolling surface 19, and between the surface of the winding
core A2
and the web material N entrained around the cylindrical surface of the first
winding
roller 1. This ensures that, as a result of the rotation movement of the first
winding
roller 1 and of feed of the web material N, the winding core A2 accelerates
angularly,
starting to roll along the rolling surface 19, pushed by the web material N
and by the
first winding roller 1 against which the web material N is pressed.
Along the second portion 19B of the rolling surface 19, the radial dimension
of the feed channel 21 can increase gradually, thus reducing deformation of
the diam-
eter of the winding core A2 and allowing winding of the web material N around
it to
start, with consequent formation of turns of a new log.
The step 19G, if provided, can facilitate the initial angular acceleration
phase
of the winding core A2.
Durante the rolling movement of the winding core A2 in the feed channel 21,
the line of glue C applied to the winding core A2 comes into contact with the
web
material N, causing adhesion of the web material N to the winding core.
In this step of the winding cycle, breaking or severing of the web material N
also takes place by means of the severing member 23. This latter is made to
pivot
against the first winding roller 1, so as to pinch, with the pads 24A, the web
material
N against the surface of the first winding roller 1. As the winding rollers 1,
3 and 8
continue to rotate winding the web material N on the log Li, the web material
is
stretched between the log Li and the pinch point of the web material N against
the
first winding roller 1 by the severing member 23.
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When the tension exceeds the breaking point, for example at a perforation
line of the web material N, this latter breaks generating a trailing edge Lf,
which is
wound on the log Li, and a leading edge Li, which is wound on the new winding
core A2., The leading and trailing edges Li and Lf are schematically shown in
Fig. 3.
In this embodiment of the winding method, when severing of the web material N
is
performed, the winding core A2 passes through the portion of smaller radial
dimen-
sion of the insertion channel 21 of the winding cores A2, i.e. at the step
19G. In other
embodiments, severing of the web material N can take place before or after
passage
of the winding core A2 over the step 19G.
In some embodiments, winding can start without the use of glue C, for exam-
ple by electrostatically charging the web material N and/or the winding core
A2, or
using a suction system, optionally inside the winding core A2, which can be
provided
with suction holes. In other embodiments, winding can start with the aid of
air jets. In
yet other embodiments, start of winding can be obtained or facilitated through
suita-
ble control of the movement of the severing member 23. For example, the
severing
member can be controlled to form a loop of web material N, which is wound
around
the winding core.
While in the sequence of Figs. 1 to 5, the movement of the severing member
23 is alternating reciprocating movement, in other embodiments the movement of
the
severing member 23 can be always in the same direction, for example clockwise
in
the drawing. The speed of the severing member can be controlled so as to cause
breaking or severing of the web material between the pinch point of the web
material
N by the pads 24A and the log Li, for example by rotating the severing member
23
with a speed so that the pads 24A are fed at a lower speed than the peripheral
speed
of the first winding roller 1. In other embodiments, the speed of the pads 24A
can be
greater than the peripheral speed of the first winding roller 1. In this case,
breaking or
severing of the web material N can take place between the pinch point of the
web
material N by the pads 24A and the pinch point of the web material N between
the
first winding roller 1 and the new winding core A2.
In other embodiments, not shown, the severing member can be configured
differently, and perform, for example, cutting of the web material, using a
blade that
cooperates with a counter-blade on the first winding roller 1. In yet other
embodi-
ments, severing of the web material can be obtained with a severing member
housed
in the first winding roller 1 or between this latter and the path of the web
material N,
the severing member being configured and controlled to sever the web material
act-
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ing from the side of the web material N facing the winding roller 1.
Fig.4 shows the subsequent step, in which the second winding core A2, roll-
ing along the rolling surface 19, leaves the rolling surface 19 and comes into
contact
with the cylindrical surface of the third winding roller 7, which is located
at the end
of the insertion channel 21 for the winding cores.
The third winding roller 7 can be provided with a series of annular grooves 7S
, into which the ends of the plates that form the terminal part 19B of the
rolling sur-
face 19 are inserted. In this way, the winding core A2 is gently transferred
from the
rolling surface 19 to the surface of the third winding roller 7.
Rolling on the surface of the third winding roller 7 and remaining in contact
with the web material N driven around the first winding roller 1, the winding
core
A2, or more precisely the new log L2 that starts to form there around, also
comes into
contact with the second winding roller 3, as shown in Fig.4. Therefore, in
practice the
path of the winding cores extends between the first winding roller 1 and the
third
winding roller 5 and through the nip 5 between the first winding roller 1 and
the sec-
ond winding roller 3.
To allow feed of the winding core A2 along the feed channel 21, the severing
member 23 is rotated around the axis 23A until it exits from the feed channel
21. The
glue C (or another means or member for starting winding) has caused adhesion
of the
web material N to the winding core A2, so that the web material starts to wind
on the
winding core A2 starting the formation of a second log L2 while the core is
fed by
rolling along the channel 21.
During the operations described above, the first log Li starts the movement of
ejection from the second winding cradle 10, for example as a result of a
variation of
the peripheral speeds of the rollers 1, 3 and 8. In some embodiments the
fourth wind-
ing roller 8 can be accelerated and/or the second winding roller 3 can be
decelerated
to cause the log Li to move away from the second winding cradle 10 toward a
dis-
charge chute 31. The fourth winding roller 8 moves upward to allow passage of
the
log Li toward the discharge chute 31.
In Fig.4 the second winding core A2 is located in the first winding cradle 6
and is in contact with the first winding roller 1, the second winding roller 3
and the
third winding roller 7 and the second log L2 is being formed there around. The
com-
pleted log Li is discharged on the chute 31. The second winding core A2 passes
through a nip or space defined between the first winding roller 1 and the
third wind-
ing roller 7, before coming into contact with the second winding roller 3.
Subse-
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quently, as described below, the winding core A2 with the log L2 being formed
there
around also passes through the nip 5 between the first winding roller 1 and
the sec-
ond winding roller 3.
Forming of the second log L2 continues through feed of the web material N
around the new winding core A2 and consequent increase of the diameter of the
new
log L2. The third winding roller 7 can move due to the movement of the arms 9
around the fulcrum or axis 9A, following the increase of diameter of the
second log
L2. The portion 19B of the rolling surface 19 can follow the movement of the
third
winding roller 7, so as not to obstruct the movement of this latter toward the
nip 5 be-
tween the first winding roller 1 and the second winding roller 3.
After having performed a part of the winding cycle in the cradle 6, the log L2
is moved to the second winding cradle 10 where winding of the log is
completed. For
this purpose, it is necessary to pass the log L2 through the nip 5. To do
this, in some
embodiments one or preferably both the winding rollers 1 and 3 can be
supported by
respective arms 1B, 3B such as to pivot around axes of oscillation 1C, 3C.
As can be seen in Fig.5, which shows an intermediate step of the passage
from the winding cradle 6 to the winding cradle 10, the distance between
centers of
the winding rollers 1 and 3 is gradually increased, for example by pivoting
the arms
1B, 3B. In other embodiments, the winding rollers 1, 3 can be carried by
slides pro-
vided with a translation movement, instead of a pivoting or rotation movement.
Whatever the mechanism used to modify the distance between centers of the
winding rollers 1 and 3, their movement away from each other (Fig.5) allows
the log
L2 to pass through the nip 5 and enter the winding cradle 10.
In some embodiments, during this step the third winding roller 7 can move
gradually toward the second winding cradle 10, accompanying the log L2. In
this
way, winding continues to take place in contact with at least three winding
rollers 1,
3,7.
The fourth winding roller 8, which was raised to allow growing of the log Li
followed by discharge thereof toward the chute 31, is returned toward the nip
5 until
it comes into contact with the log L2, which is fed through the nip 5. For a
part of the
winding cycle the log L2 can be in contact with all four winding rollers 1, 3,
7 and 8.
The third winding roller 7 can move toward the nip 5 following the log L2 un-
til it is made to pass beyond the nip between the rollers 1 and 3. From this
point on,
the log L2 can be in contact only with the rollers 1, 3 and 8 and finish being
wound in
the second winding cradle 10.
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The feed movement of the axis of the log L2 can be suitably obtained with a
control of the movement of the winding rollers, which by modifying the mutual
posi-
tion of their axes, move the log L2 into the, and through the, area of minimum
dis-
tance between the rollers 1 and 3. For example, movement can be obtained by
push-
ing the log with the third winding roller 7. In some embodiments the movement
of
the log can be facilitated, supported or influenced through temporary
variation of the
peripheral speeds of the winding rollers, for example by decreasing the
peripheral
speed of the second winding roller 3 for a short time.
While the embodiment shown in Fig.5 includes a step in which the log L2 is
in contact with the four winding rollers 1, 3, 7 and 8, in other embodiments
the third
winding roller 7 could lose contact with the log L2 before it passes through
the nip 5,
beyond the point of minimum distance between the winding rollers 1 and 3, and
comes into contact with the fourth winding roller 8. However, in the
embodiment
shown, better control of the log is obtained in the various steps of
formation, as the
log is always in contact with at least three winding rollers.
The time for which the second winding core A2 remains in the position of
Fig. 5, i.e. in the winding cradle 6, can be controlled simply by acting on
the periph-
eral speed of the winding rollers 1, 3 and 7 and/or on the position of the
rollers. The
second winding core A2 will remain substantially in this position, without
being fed
further, for the whole of the time in which the peripheral speeds of the
winding roll-
ers 1, 3 and 7 remain the same as one another. As mentioned above, subsequent
ad-
vancement is obtained, for example, by decelerating the second winding roller
3. It is
thus possible to set the amount of web material N that is wound around the
winding
core A2 as desired, retaining this latter and the second log L2 that is formed
there
around in the winding cradle 1, 3, 7 for the desired time.
Once the log L2 is located in the second winding cradle 10, winding of the
second log L2 continues until reaching the condition of Fig. 1. The third
winding roll-
er 7, which can be moved toward the nip 5 to accompany the movement of the log
L2
through the nip in the second winding cradle 10, can return to the initial
position of
Fig.1, in which it cooperates with the severing member 23.
In some embodiments, the structure of the members of the rewinding machine
is such that the path followed by the center of the winding cores Al, A2 from
the
time in which they come into contact with the three winding rollers 1, 3 and 7
to the
time in which the log starts to be discharged between the rollers 1, 3 and 8,
losing
contact with the winding roller 7, is substantially rectilinear. This allows
more regu-
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lar winding and facilitates the use of centers that can be inserted into the
opposed
ends of the winding cores in order to improve control of the rotation and feed
move-
ment of the core and of the log during the winding cycle, combining the
peripheral
winding technique with an axial or central winding, as described, for example,
in the
US patent no. 7,775,476 and in the publication US-A-2007/0176039.
With the described arrangement of the four winding rollers and the path of the
winding cores between the first winding roller 1 and the third winding roller
7, it is
possible to provide the first and the second winding roller 1, 3 with
relatively large
diameter, and such that an intermediate support is not required, even when the
wind-
ing cores have a small diameter. Control of the winding cores of small
diameter is
nonetheless guaranteed also with winding rollers 1, 3 of relatively large
diameter, as
the third winding roller 7 can be provided with a smaller diameter. The lower
flexural
rigidity of the third winding roller 7 due to the smaller diameter of this
roller can be
offset using one or more intermediate supports. In some embodiments, the third
winding roller 7 can be associated with a supporting and stiffening beam,
which ex-
tends parallel to the axis 7A of the third winding roller 7, in an area in
which this
beam does not interfere with the path of the web material N and with the logs
Li, L2
being formed. The beam can be positioned, for example, at the elements 19C, or
in a
diametrically opposite position with respect thereto, i.e. in an area in which
the third
winding roller 7 does not cooperate with the web material N and/or with the
log Li,
L2 being formed.
In the embodiment shown in the accompanying figures, the first winding roll-
er 1 and the second winding roller 3 have substantially the same diameter and
are
both mounted with movable axes to increase and decrease the dimension of the
nip 5,
through which the logs being formed around the respective winding cores pass.
In
other embodiments, the winding roller 1 can be provided with a different
diameter,
for example larger than the winding roller 3. By increasing the diameter of
the wind-
ing roller the support system of said roller can be simplified, as a larger
diametrical
dimension implies greater flexural rigidity.
Moreover, in some embodiments, only one of the two winding rollers 1 and 3
can have a movable axis, while the other has a fixed axis. In this way, the
number of
actuators required for movement of the various members of the rewinder is
reduced
and the law for controlling the motion of the winding rollers is simplified.
If the two
winding rollers 1 and 3 have different diameters, it is advantageous for the
winding
roller of larger diameter, for example the winding roller 1, to have a fixed
axis, while
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the winding roller of smaller diameter has a movable axis. In this
configuration the
winding sequence of the web material around the winding core does not change.
Winding starts in the winding cradle 6 and ends, after passage of the log
being wound
through the nip 5, in the second winding cradle 10.
In yet further embodiments, the winding rollers 1 and 3 can both be movable,
but can carry out asymmetrical movements.
In some embodiments, the rewinding machine described above can be provid-
ed with a system of motorized centers, which engage, guide and control the
winding
cores during at least a part of their travel between the winding cradle 6
defined by the
rollers 1, 3 and 7, upstream of the nip 5, and the winding cradle 10 formed by
the
rollers 1, 3 and 8, downstream of the nip 5.
The system of centers can comprise, on each side or side member of the ma-
chine, a center 101 for engaging the respective end of a winding core Al, A2
that is
inserted into the winding area. Figs.6 and 7 show one of these centers and the
related
operating mechanism.
The center 101 can have a rod 103 that ends with a head 105. The head 105
can have a mechanism to engage the tubular winding core. In some embodiments,
the
head 105 can engage with the winding core by being inserted therein. The head
105
can have expansible members, to torsionally engage the winding core. In some
em-
bodiments, the expansible members comprise expansible annular members 107, for
example pneumatically expansible, through a compressed air feed system. The
com-
pressed air can be conveyed through ducts 109.
The center 101 can be provided with a translation movement according to ar-
row fl 01, parallel to the longitudinal axis X-X of the center.
An actuator, for example a piston-cylinder actuator 111, can be used to con-
trol the reciprocating translation movement according to the double arrow fl
01. This
movement allows the heads 105 of opposed centers 101 on the two sides of the
ma-
chine to be moved toward each other, until the heads 105 engage with the ends
of the
respective winding core Al, A2 that is located in the winding area. The heads
105
can be made to partially or totally penetrate the ends of the winding core.
As can be seen in particular in Fig.6, each center 101 can be provided with a
motor 115, for example an electronically controlled electric motor, which
rotates the
respective center 101 around its axis X-X. The motion can be transmitted from
the
motor 115 to the center 101 by means of a belt 117, for example a toothed
belt. The
toothed belt 117 can be driven around a pulley 119 torsionally constrained to
the rod
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103 of the respective center 101. More in particular, the pulley 119 can be
fitted onto
a sleeve 121, inside which the rod 103 of the center 101 can slide according
to the
double arrow f101, the sleeve 121 being torsionally coupled to the rod 103,
for ex-
ample through a grooved profile or the like. The sleeve 121 can be supported
by
means of bearings 123 inside a bushing 125 that can be carried by a slide 127.
The slide 127 can be mounted on stationary guides 129, i.e. integral with the
load-bearing structure of the rewinding machine. In this way, the slide 127
can be
translated according to the double arrow f127 in the direction defined by the
guides
129. In some embodiments the rectilinear alternating movement according to
f127
can be imparted by a motor 131, for example an electronically controlled
electric mo-
tor. The electric motor 131 can cause the oscillation of a crank 133,
wherefrom mo-
tion is transmitted through a connecting rod 135 to the slide 127, the
connecting rod
135 being hinged in 135A to the slide 127 and in 135B to the crank 133.
The movement according to the double arrow f127 can be substantially recti-
linear and parallel to the movement of the center of the winding core Al, A2
when
this passes from one to the other of the two winding cradles definite by the
sets of
three rollers 1, 3, 7 and 1, 3, 8, during the winding process described above.
The cen-
ters 101 can engage with the winding core Al, A2 when this is in the winding
cradle
6 upstream of the nip 5 and can disengage therefrom when the log Lb is almost
fin-
ished, thus allowing discharge of this latter according to the description
above with
specific reference to the step shown in Figs. 3 and 4.
During the movement according to the double arrow f127, and more in par-
ticular during the step of upward movement (in the figure) of the centers 101,
these
accompany the winding core while the log Lb grows in diameter, while the motor
115 imparts, by means of the belt 117, a rotation movement to the centers 101,
which
is transmitted to the winding core and therefore to the log being formed, as a
result of
torsional coupling between the heads 105 of the centers 101 and the winding
core
Al, A2. The rotation speed imparted by the motor 115 can be controlled, so as
to be
coherent with the peripheral speed of the log Lb being wound.
The use of the centers 101 allows better control of winding and of the
advaincement of the log Lb from one to the other of the two winding cradles 6,
10
and through the nip 5 during all steps of the winding cycle.
In the embodiments shown in Figs. 1 to 8, the first winding roller 1 and the
second winding roller 3 have substantially the same diameter and can both have
a
movable axis, to favor passage of the core and of the web in the first winding
step
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from the first winding cradle 6 to the second winding cradle 10. In other
embodi-
ments, the first winding roller 1 and the second winding roller 3 can have
different
diameters and preferably the first winding roller 1 can have a larger diameter
than the
second winding roller 3.
In possible embodiments, one of the winding rollers 1 and 3 can have a fixed
axis and the other a movable axis.
Preferably, the first winding roller 1, around which the web material N is
wound and guided, can have a fixed axis and have a larger diameter than the
second
winding roller 3.
Fig.9 shows a configuration of this type. The same numbers indicate the same
or equivalent parts to those described with reference to Figs. 1 to 8. In
particular, the
four winding rollers are indicated with 1, 3, 7 and 8. Around the first
winding roller 1
there is formed a channel 21 for insertion of the winding cores Al, A2. The
channel
is delimited by the cylindrical surface of the first winding roller 1 and by a
rolling
surface 19 that extends around the first winding roller 1 and toward the third
winding
roller 7. The winding cores are inserted into the channel 21 so as to be in
contact with
the rolling surface 19 and with the web material N entrained around the first
winding
roller 1. The rolling surface 19 can have a sort of intermediate step, as
indicated in
19G, to facilitate angular acceleration of the winding core and gripping of
the web
material after severing caused, in the same way as already described above, by
means
of a severing member 23 of the web material N. This severing member 23 of the
web
material cooperates with the first winding roller 1 pinching the web material
between
the first winding roller and one or more pressers 24A carried by the severing
member
23.
The rotation axis lA of the first winding roller 1 is stationary with respect
to
the load-bearing structure of the machine 1, so as to make feed of the web
material N
up to the nip 5 between the first winding roller 1 and the second winding
roller 3
more stable and more easily controlled.
In this embodiment the second winding roller 3 has a diameter substantially
smaller than the diameter of the first winding roller 1. For example, the
diameter of
the second winding roller 3 can be less than half the diameter of the first
winding
roller 1. The second winding roller 3 can be supported by lateral side members
4, as
indicated schematically in Fig. 9. Between the lateral side members 4
intermediate
supports can be arranged, which support the second winding roller 3 in
intermediate
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positions between the ends of this latter. In this way, it is possible to
design the sec-
ond winding roller 3 with a small diameter
To obtain sufficient rigidity of the second winding roller 3, the side members
4 and any intermediate supports can be constrained to a transverse beam 14.
The axis 3A of the second winding roller 3 can be movable and pivot around
a pivoting axis defined by a pivot point 16 of the side members 4 to the load
bearing
structure of the rewinding machine 2. The pivoting movement of of the second
wind-
ing roller 3 can be controlled by a motor 18 associated with a crank 20. A
connecting
rod, also pivoted in 22B to the respective side member 4, can be pivoted in
22A to
the crank 20. The reciprocating rotation movement of the motor 18 pivots the
axis
3A of the second winding roller 3 around the axis defined by the pivot point
16. In
some embodiments, two symmetrical motors 18 can be provided, to act on two op-
posed side members 4. Between the side members 4 there can be fixed the chute
31,
or a part thereof, so that said chute 31 can follow the movement of the second
wind-
ing roller 3.
The third winding roller 7 is carried by side members 32 constrained to a
transverse beam 34 and pivoted in a pivot point 36 to the stationary structure
of the
rewinding machine 2. Intermediate supports can be integral with the transverse
beam
34 to support the third winding roller 7 in intermediate points between the
two ends
thereof, supported by the side members 32. Pivoting of the third winding
roller 7, i.e.
the translation movement of its rotation axis 7A to follow the movement of the
wind-
ing cores and of the logs being formed, can be imparted by a motor 42 by means
of a
connecting rod-crank system 44, 46 constrained to the transverse beam 34 in
46A.
A portion 19C of the rolling surface 19 can be constrained to the side mem-
bers 32, which portion in this way can follow the translation movement of the
third
winding roller 7 during the various steps of the winding cycle.
The operating sequence of the machine 2 of Fig. 9 is substantially the same as
the one described with reference to Figs. 1 to 5 and therefore will not be
described in
detail. Fig. 9 shows a completed log Li, ready to be discharged from the
second
winding cradle 10, and a second winding core A2 already inserted into the
first wind-
ing cradle 6, between the winding rollers 1, 3, 7. The operating condition
shown in
Fig. 9 can actually occur in the machine, but this is not indispensible.
Depending on
the type of regulation, the case in which the second winding core A2 reaches
the po-
sition of Fig. 9 when the log Li has already been ejected from the second
winding
cradle 10 can also occur.
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The passage of the second winding core A2, with the log being formed there
around, through the nip 5 defined by the first winding roller 1 and by the
second
winding roller 3 is allowed or facilitated by moving only the axis 3A of the
second
winding roller 3, while the axis lA of the first winding roller 1 remains
stationary
with respect to the structure of the machine. In this way, the operation of
the rewind-
ing machine is made more uniform, in particular as the path of the winding
material
upstream of the nip 5 is not modified.
A further advantage of the embodiment of Fig. 9 consists in that operation of
the severing member 23 of the web material N is simplified. In fact, it co-
acts with a
winding roller 1, whose rotation axis does not move and therefore control of
the sev-
ering step of the web material N is simplified.
The use of a first winding roller 1 of larger diameter makes it possible to
avoid the need for an intermediate support of the first winding roller 1,
simplifying
the structure of the machine and improving the quality of the logs.
