U.S. patent application number 12/737752 was filed with the patent office on 2011-06-09 for rewinding machine and winding method.
This patent application is currently assigned to Fabio Perini S.p.A.. Invention is credited to Mauro Gelli, Roberto Morelli.
Application Number | 20110133015 12/737752 |
Document ID | / |
Family ID | 40940436 |
Filed Date | 2011-06-09 |
United States Patent
Application |
20110133015 |
Kind Code |
A1 |
Gelli; Mauro ; et
al. |
June 9, 2011 |
REWINDING MACHINE AND WINDING METHOD
Abstract
The rewinding machine includes a weakening device for weakening
the web material along a substantially transverse weakening line,
along which the web material is severed at the end of the winding
of a log. The weakening device is controlled so as to generate the
weakening line in a manner synchronized with the completion of
winding of the log.
Inventors: |
Gelli; Mauro; (Lucca,
IT) ; Morelli; Roberto; (Lucca, IT) |
Assignee: |
Fabio Perini S.p.A.
Lucca
IT
|
Family ID: |
40940436 |
Appl. No.: |
12/737752 |
Filed: |
September 18, 2009 |
PCT Filed: |
September 18, 2009 |
PCT NO: |
PCT/IT2009/000423 |
371 Date: |
February 14, 2011 |
Current U.S.
Class: |
242/521 |
Current CPC
Class: |
B65H 19/283 20130101;
B65H 2301/418925 20130101; B65H 19/267 20130101; B65H 19/2269
20130101; B65H 2301/5152 20130101 |
Class at
Publication: |
242/521 |
International
Class: |
B65H 35/10 20060101
B65H035/10; B65H 18/08 20060101 B65H018/08; B65H 19/26 20060101
B65H019/26; B65H 19/28 20060101 B65H019/28 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 24, 2008 |
IT |
FI2008A000181 |
Claims
1-26. (canceled)
27. Rewinding machine for producing logs of web material,
comprising a feed path of a web material, a winding cradle and a
perforator, which forms perforation lines in said web material in
order to divide said web material into single sheets that can be
detached along said perforation lines; and said rewinding machine
further comprising a weakening device for weakening the web
material along a substantially transverse weakening line, along
which the web material is severed at an end of winding of a log,
said weakening device being arranged to generate said weakening
line in a manner synchronized with the end of winding of said log
and substantially matching one of said perforation lines.
28. The rewinding machine as claimed in claim 27, wherein said
weakening device comprises an applicator for applying a liquid
along said weakening line.
29. The rewinding machine as claimed in claim 28, wherein said
applicator applies water along said weakening line.
30. The rewinding machine as claimed in claim 28, wherein said
applicator applies a liquid containing an adhesive along said
weakening line.
31. The rewinding machine as claimed in claim 27, further
comprising a winding core inserter.
32. The rewinding machine as claimed in claim 31, further
comprising a glue applicator for applying glue on said winding
cores.
33. The rewinding machine as claimed in claim 27, wherein said
weakening device comprises a rotating element with a liquid
dispenser, said rotating element being synchronized with the
winding of the log in order to apply said liquid along the
weakening line at the end of winding of each log.
34. The rewinding machine as claimed in claim 33, wherein said
rotating element cooperates with a rotating roller supporting the
web material, whose peripheral speed is substantially equal to
speed of the web material at least during application of the liquid
by said liquid dispenser.
35. The rewinding machine as claimed in claim 33, wherein said
applicator is arranged to come into contact with the web material
resting on a rotating roller in a manner synchronized with movement
of the web material, during the contact a transferring system
having a speed substantially equal to the speed of the web material
at the contact.
36. The rewinding machine as claimed in claim 34, wherein said
applicator is arranged to come into contact with the web material
resting on said rotating roller in a manner synchronized with
movement of the web material, during the contact a transferring
system having a speed substantially equal to the speed of the web
material at the contact.
37. The rewinding machine as claimed in claim 34, wherein the feed
path of said web material develops around said roller, the web
material being guided around said roller.
38. The rewinding machine as claimed in claim 35, wherein the feed
path of said web material develops around said roller, the web
material being guided around said roller.
39. The rewinding machine as claimed in claim 34, wherein said
rotating roller constitutes one of a plurality of winding rollers
forming said winding cradle.
40. The rewinding machine as claimed in claim 35, wherein the feed
path of said web material develops around said rotating roller, the
web material being guided around said rotating roller.
41. The rewinding machine as claimed in claim 37, wherein the feed
path of said web material develops around said rotating roller, the
web material being guided around said rotating roller.
42. The rewinding machine as claimed in claim 27, wherein said
winding cradle comprises a first winding roller around which said
web material is fed and guided, and a second winding roller forming
with said first winding roller a nip for transit of winding cores
in an initial phase of a winding cycle; and wherein said weakening
device is arranged to act upstream of said nip relative to a
direction of feed of the web material.
43. The rewinding machine as claimed in claim 42, further
comprising a rolling surface arranged around the first winding
roller and upstream of said nip relative to the direction of feed
of the web material, defining a channel between said first winding
roller and said rolling surface, and wherein said weakening device
is arranged to act on the web material upstream of said
channel.
44. The rewinding machine as claimed in claim 43, further
comprising a core inserter arranged to feed said winding cores into
said channel.
45. The rewinding machine as claimed in claim 42, wherein said
first winding roller has apertures for exit of air therefrom so as
to facilitate detachment of a free end of the web material.
46. The rewinding machine as claimed in claim 39, wherein said one
of a plurality of winding rollers has a knurled surface or an
engraved surface.
47. The rewinding machine as claimed in claim 27, further
comprising a blowing system to facilitate winding of a first turn
of web material around a winding core.
48. The rewinding machine as claimed in claim 27, further
comprising a first glue applicator and a second glue applicator, to
apply glue on winding cores in two angularly offset areas, a first
area coming into contact with a portion of the web material forming
a tail of a complete log and a second area coming into contact with
a portion of the web material forming an initial part of a new log
of web material.
49. The rewinding machine as claimed in claim 27, wherein said
weakening device comprises a mechanical system or a pneumatic
system synchronized with a winding cycle of the logs.
50. A method for winding rolls of web material around winding
cores, comprising: feeding the web material along a feed path;
subdividing said web material into single portions that can be
detached along transverse perforation lines; winding a quantity of
the web material in order to form a first log of web material; when
a given quantity of web material has been wound on said log,
severing the web material in a severing position along said feed
path, forming a tail portion of the first log and a head portion
for starting the winding of a second log; starting the winding of
said second log; wherein at end of the winding of said log, in a
weakening position arranged along the feed path of the web material
upstream of the severing position, a weakening line is formed on
the web material at one of said transverse perforation lines; the
web material is fed along said feed path moving said weakening line
towards said severing position; and the web material is severed in
said severing position.
51. The method as claimed in claim 50, further comprising winding
said logs around winding cores.
52. The method as claimed in claim 50, further comprising gluing
the head portion of the web material on a winding core at start of
the winding of each log.
53. The method as claimed in claim 50, further comprising weakening
said web material by applying a liquid along said weakening
line.
54. The method as claimed in claim 51, further comprising weakening
said web material by applying a liquid along said weakening line
and wherein said liquid also serves to anchor the head portion of
the web material on the winding core.
55. Rewinding machine for producing logs of web material,
comprising a feed path of a web material, a winding cradle, and
weakening device; said weakening device comprising an applicator
for applying a liquid along a substantially transverse weakening
line for weakening the web material along said weakening line,
along which the web material is severed at end of winding of a log,
said weakening device serving to generate said weakening line in a
manner synchronized with the end of winding of said log.
56. Method for winding rolls of web material around winding cores,
comprising: feeding the web material along a feed path; winding a
quantity of the web material in order to form a first log of web
material; when on said log a given quantity of the web material has
been wound, severing the web material in a severing position along
said feed path, forming a tail portion of the first log and a head
portion for starting winding of a second log; starting the winding
of said second log; wherein at end of the winding of said log, in a
weakening position arranged along the feed path of the web material
upstream of the severing position, a weakening line is formed on
the web material by applying a liquid along said weakening line;
feeding the web material along said feed path moving said weakening
line towards said severing position; and severing the web material
in said severing position.
Description
TECHNICAL FIELD
[0001] The present invention relates to a winding or rewinding
machine for forming rolls of web material. According to another
aspect the invention relates to a method for winding a web material
in rolls.
STATE OF THE ART
[0002] In numerous industrial fields, and in particular in the
field of paper converting--especially converting of tissue paper
for producing rolls of toilet paper, rolls of kitchen towels and
the like--so called rewinding machines are used that, starting from
one or more paper material reels of large diameter, form individual
logs of axial dimension equal to the width of the web material,
typically 2-5 m, and of diameter equal to the diameter of the rolls
destined for the final consumption. The logs produced by the
rewinding machine are subsequently cut into a plurality of rolls of
the desired axial length.
[0003] In the modern rewinding machines, winding is carry out
through a so called peripheral or surface system, wherein the log
being formed is maintained in a winding cradle formed by a
plurality of rollers rotating in a concordant direction and in
surface contact with the log being formed so as to transmit the
winding motion. In other older rewinding machines winding is
carried out in a cradle, in which the log is maintained on a
winding spindle, to which the rotation movement is imparted. There
are also machines combining a peripheral winding system with
spindles or tail chucks for supporting and controlling the log
being formed.
[0004] In general, the rewinding machines have members for
interrupting the web material, which is fed continuously by the
reels present in the unwinders, at the end of winding of each
individual log. These severing members are synchronized with the
means or devices that start winding of the subsequent log.
[0005] In some rewinding machines winding is carried out around
tubular winding cores mounted on winding spindles. The tubular
cores are usually made of plastic, paper or cardboard, and they
remain inside the log after winding. In other rewinding machines
the winding spindle is extracted so as to obtain a log provided
with a central hole, but devoid of winding cores. In further types
of rewinding machines winding is carried out without a winding
spindle, by simply winding the web material around itself, starting
from a central nucleus and forming around this latter the finished
log.
[0006] Independently of the type of used rewinding machine, the
start of the winding of each individual log is one of the critical
aspects during the winding phases. When winding is carried out
around tubular cores, one of the critical aspects is represented by
the transport of the leading end, formed by cutting or severing the
web material, to the new core and by the start of the winding of
the first turns. Different systems have been designed to perform
the operations of severing the web material, transporting and
anchoring the winding cores. U.S. Pat. No. 6,648,266 and U.S. Pat.
No. 5,979,818 disclose a particularly efficient rewinding machine,
wherein the web material is severed by means of a rotating member
which pinches the web material against a movable surface, for
example against the surface of the main winding roller of a winding
cradle of the peripheral type. The winding core, is provided with a
glue to anchor the leading edge generated by severing and to start
in this way the winding of the subsequent log. The severing member
acts on the web material in a position intermediate between the log
which has been just wound and the new winding core inserted in the
machine.
[0007] Rewinding machines produced according to this principle are
extremely efficient and allow to achieve high winding speeds thanks
to the efficient control on the free end of the web material after
it has been severed. However, due to the way in which the web
severing system is designed, the logs are formed around the winding
cores with a head portion forming, inside each log, a fold of
particularly great length. This entails irregularities in the first
winding turns and a quality of the finished product not equal to
that which can be obtained through other slower winding systems.
Furthermore, as the severing member acts between the log, wound
during the winding cycle which is ending, and the new core which is
being inserted, it is necessary to have a particularly long rolling
surface, and therefore a particularly long insertion channel.
[0008] Other rewinding machines having web material severing
systems arranged upstream of the area of insertion of the winding
cores are disclosed in EP1525148.
[0009] WO 2007/081244 discloses a perforating device that can be
used in a rewinding machine, wherein on the toothed blades of the
perforator a colored liquid is applied. This known device has the
function of coloring the perforation lines that separate each of
the various sheets of a roll in tissue paper by means of the
liquid.
SUMMARY OF THE INVENTION
[0010] According to one aspect, an object of the present invention
is to provide a rewinding machine that completely or partially
overcomes at least one of the problems of the known rewinding
machines. According to another aspect, a further object of the
present invention is to provide a winding method using a rewinding
machine, preferably of the peripheral type, wherein one or more of
the problems of the traditional methods are completely or partially
overcome.
[0011] Substantially, the invention is based upon the concept of
interrupting, severing, or cutting, the web material in two phases.
In a first phase the web material is weakened at a line, along
which severing of the web material is subsequently completed, thus
forming the tail end of the log, the winding of which is being
completed, and the leading end destined to form the subsequent
log.
[0012] According to one embodiment, the present invention provides
a rewinding machine comprising: a web material feed path; a winding
cradle, preferably of the peripheral type; severing members for
interrupting the web material at the end of winding of each log; a
weakening device for weakening the web material along a
substantially transverse severing or weakening line, in
correspondence of which the web material is severed at the end of
winding of a log. The weakening device is controlled so as to
generate the weakening line synchronized with the completion of
winding of the log.
[0013] In some embodiments the rewinding machine according to the
present invention provides an inserter for winding cores or
spindles, to produce log of web material wound about tubular
winding cores or spindles. Preferably, but not necessary, the
tubular cores are destined to remain inside the log. In some cases,
they are provided with a glue, applied for example along one or two
rows having a continuous or discontinuous development in the
substantially longitudinal direction of the tubular core, for the
purposes that will be described in greater detail hereunder.
[0014] By means of a rewinding machine of this type it is possible
to weaken the web material in an adequate position along the path
of the web material upstream of the area in which it will be
definitely severed to form the leading and tail ends during the
exchange phase, i.e. during the phase in which the finished log is
separated from the web material and unloaded from the machine and
the new log starts winding.
[0015] Through a weakening line of this type it is possible to
maintain the control on the web material fed along the feed path
across the machine, from the position in which the weakening member
or device is arranged and the position, preferably downstream
(according to the direction of feed of the web material) of the
area of insertion of the winding core, without the need for using
vacuum members or other complex retaining systems for retaining the
leading end of the web material. Moreover, the weakening of the web
material upstream of the area of insertion of the winding core
allows to obtain the subsequent complete severing of the web
material with a particularly simple system, for example with a very
limited acceleration of one of the winding rollers forming the
winding cradle. This can be obtained thanks to the fact that the
web material has been previously weakened along the weakening line
during the first phase of the operations for severing the
material.
[0016] In some embodiments, when a winding core is used, provided
with a glue to transfer on the core itself the free leading end of
the web material, severing of the web material can be completed
simply due to the effect of the adhesion between the web material
and the core by means of the glue applied on the core. In this case
the severing members for interrupting the web material are
represented by the same core inserter which is synchronized with
the position of the weakening line generated on the web
material.
[0017] According to a different aspect the invention relates to a
method for winding logs of web material about winding cores,
wherein: at the end of winding of a log, in a weakening position
arranged along the feed path of the web material upstream of the
severing position, a weakening line is formed on the web material;
the web material is fed along the feed path, bringing said
weakening line towards the severing position, and is severed in
said severing position.
[0018] In some embodiments it is provided for the web material to
be weakened by applying a liquid, preferably a water based liquid,
in correspondence of said weakening line.
[0019] Further advantageous features and embodiments of the
rewinding machine and of the method according to the present
invention are indicated in the appended claims and shall be
described hereunder with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The invention will be better understood by following the
description below and the attached drawing, which shows a
non-limiting practical embodiment of the present invention. More
particularly, in the drawing:
[0021] FIGS. 1A to 1F show a schematic side view of a rewinding
machine according to a first embodiment of the present invention,
in a winding operative sequence;
[0022] FIGS. 1G to 1I schematically show the formation of the
weakening line and the subsequent tearing or severing of the web
material along said line;
[0023] FIG. 2 shows a schematic side view of a rewinding machine
according to the present invention in a further embodiment;
[0024] FIG. 3 shows a schematic side view of a rewinding machine
according to a further embodiment of the present invention;
[0025] FIG. 4 shows a partial schematic side view of a rewinding
machine in a modified embodiment;
[0026] FIG. 5 shows a schematic enlargement of the surface of the
main winding roller of the rewinding machine in an improved
embodiment; and
[0027] FIGS. 6A to 6D show an operative sequence of a further
embodiment of a rewinding machine according to the present
invention.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0028] With initial reference to FIGS. 1A to 1F, in one embodiment
the rewinding machine 1 comprises a winding cradle with a first
winding roller 3, a second winding roller 5 and a third winding
roller 7. Between the rollers 3 and 5 a nip 9 is defined, through
which the web material N passes, fed along a winding path described
in greater detail hereunder and developing around the first winding
roller 3. The winding roller 7 is provided with a movement for
moving towards and away from the winding rollers 3 and 5, so that
the three rollers 3, 5, 7 form a winding cradle of variable
dimension to allow the increase of the diameter of each log R
formed inside the cradle.
[0029] In some embodiments the rewinding machine 1 has a
perforating unit 11 (FIG. 11A) to generate perforating and severing
lines on the web material N at regular intervals, so as to
subdivide the web material N into individual small sheets, which
can be separated from each other for the use. The perforating unit
11 is known per se and will not be described in greater detail
hereunder. In other not shown embodiments the perforating unit 11
can be controlled so as to generate an individual perforating line,
or it can be completely omitted, for example for producing logs R
with a greater diameter destined to the industrial use instead of
the domestic use.
[0030] The path of the web material N develops through the
perforating unit 11 (if present) and around a guide roller 13
arranged nearly close to the winding roller 3, around which the
path of the web material N continues to develop until it achieves
and crosses the nip 9 between the winding rollers 3 and 5 and then
enters into the winding cradle in order to wind around the winding
core A and form the log R.
[0031] The above described structure is a typical structure of a so
called surface or peripheral rewinding machine, wherein the log R
is formed by maintaining it in rotation by contact between the
rollers 3, 5, and 7. Also different conformations can be provided
for the winding cradle and/or the presence of tail chucks for
supporting and controlling the winding cores in at least some of
the phases of formation of a log, as it is well known to those
skilled in the art.
[0032] According to some embodiments, around the winding roller 3 a
rolling surface 15 develops, defining a channel 17 between the
surface 15 and the cylindrical surface of the winding roller 3. The
winding cores A are sequentially inserted, in the manner described
below, inside the channel 17 so as to start the cycle of winding of
each log.
[0033] The rewinding machine 1 comprises a weakening device 21
arranged, designed and controlled so as to weaken the web material
N in correspondence of a weakening line, along which the web
material N will be subsequently severed to form the tail end of the
log R and the head end from which the winding of the subsequent log
will start.
[0034] In some embodiments, the weakening device 21 comprises an
element 23 that rotates in a controlled manner around an axis of
rotation 23A substantially parallel to the axis of rotation of the
rollers 3, 5, 7, and 13.
[0035] In some embodiments, as shown in the drawing, the weakening
device 21 is designed so as to apply a liquid, preferably for
example a water-based liquid, on the web material N along a
substantially transverse line. In some embodiments the liquid can
be simply water, although other embodiments would be possible, for
example the application of a colored liquid when one desires for
example optically to mark the position of the severing line of the
web material. In other embodiments the liquid applied by the
weakening device 21 can be constituted by or can contain an
adhesive or glue, so that following the complete severing of the
web material the free tail end can automatically adhere to the
formed log R and/or the head end can automatically adhere to the
new winding core without the need for further glue.
[0036] In the illustrated embodiment the dispensing member
comprises at least one rotating element 23, which at its distal end
is provided with a pad 25 which is wet with water or other suitable
liquid to be applied to the web material N. In order to wet the pad
25 it is possible for example to provide the rotating element 23
with a movement of immersion inside a tank 27 containing the
liquid, which is generically indicated with L. In this way the
rotating element 23 can immerse the pad 25 inside the tank 27 in
order to wet it. The extraction movement for extracting the pad 25
from the tank 27 allows the subsequent application of the liquid on
the web material as described in greater detail hereunder.
[0037] In other embodiments, as illustrated in the drawing, the pad
25 is wet with the liquid L by a movable member 20 which is
completely or partially housed inside the tank 27 and provided with
an alternate immersion and emersion motion according to the double
arrow f29. In this way it is possible to maintain the rotating
element 23 with its pad 25 completely outside the tank 27, avoiding
the movement of the element 23 for immersing the pad 25 in the
liquid L contained inside the tank. In this case the member 29
transfers the liquid from the inside of the tank 27 to the pad 25
every time it is necessary, for example for each winding cycle,
i.e. each time that an individual log R is wound. Alternatively,
guns or nozzles in series can be provided, instead of the member
29, for wetting the pad 25.
[0038] In the illustrated embodiment the logs R are wound around
substantially circular winding cores A, for example cores made of
cardboard, plastic, paper or the like. According to the illustrated
embodiment, a glue is applied on the winding cores A. The glue is
preferably applied according to two nearly longitudinal lines, i.e.
substantially parallel to the axis of the winding cores A or,
anyway, extending along the length or at least a great part of the
length of the winding cores A. The lines of glue can be continuous
or discontinuous, can be formed by individual areas of different
shape, provided that they are arranged with a frequency and a
distance from each other sufficient to guarantee the anchoring of
the free leading end formed by the web material N following the
severing thereof, as described hereunder.
[0039] In the embodiment illustrated in FIGS. 1A to 1F, a first
glue dispenser 31 and a second glue dispenser 33 are provided, to
apply two continuous or discontinuous lines of glue in angularly
staggered positions on each individual winding core A. In the
illustrated embodiment the dispensing members 31 and 33 are
substantially identical, but it is also possible to use dispensers
that are different from each other, or dispensing members with a
shape different from that illustrated. In some embodiments each
dispenser 31, 33 has a tank 31A and 33A respectively, inside which
a first glue C1 and a second glue C2 respectively are contained.
Inside each tank a movable member 31B and 33B can be immersed. The
movable members 31B and 33B are provided with an oscillating
movement according to the double arrow indicated in the drawing so
as to be immersed in the glue C1 or C2 and emerge from it until
they touch each core A to be glued along a nearly longitudinal
line. In this way, on the individual cores A two lines of glue are
applied that are angularly staggered for the purposes describe
below.
[0040] It is also possible to use movable members for lifting the
glue from the individual tanks 31A, 33A with different shapes but
having substantially the same function as the members 31B, 33B. For
example, a thread can be provided, movable along a closed path
defined for example between two pulleys. The upper segment of the
thread is arranged at an area of application of the glue to the
cores A, corresponding to the position taken by the movable members
31B, 33B when they are lifted, and a lower segment immersed in the
glue C1, C2, for example in a position corresponding to that taken
by the members 31B, 33B when they are immersed in the glue.
[0041] To the glue dispenser 31 a first transferring unit 35 is
associated, which picks up individual cores A from a storage device
37 and transfers them individually, after they have individually
received a first line of glue, to a second transferring unit 39
associated to the second glue dispensing member 33. The
transferring member 39 then transfers the cores towards the
entrance of the channel 17, into which the cores are inserted to
start the cycle of winding each individual log R according to the
method described below.
[0042] FIG. 1A shows an intermediate phase of the winding cycle of
a log R which is in the winding cradle 3, 5, 7. The transferring
member 35 has engaged a new core A, which is receiving a first line
of glue RC1 through the movable member 31B of the glue dispenser
31. The second transferring unit 39 is in a waiting position and
the movable member 33B of the second glue dispenser 33 is immersed
in the glue C2. The rotating element 23 of the weakening device 21
is in contact with the movable member 29 to receive the liquid L on
its pad 25.
[0043] In FIG. 1B the core, previously engaged by the transferring
unit 31, has been transferred by it to the transferring unit 39,
which maintains it in correspondence of the second glue dispenser
33, so as to apply on the core a second line of glue RC2, angularly
staggered relative to the line of glue RC1. The log R in the
winding cradle 3, 5, 7 has substantially achieved its final
dimension, determined for example by the length of the wound web
material. The rotating element 23 of the weakening device 21 is
still in a waiting position.
[0044] FIG. 1C shows the phase wherein the weakening device 21
applies a line of liquid L, which forms the weakening line that, in
this embodiment, matches one of the perforation lines generated by
the perforating unit 11. The second transferring unit 39 is
transferring a new core, provided with the two lines of glue RC1
and RC2, to the entrance of the channel 17.
[0045] In FIG. 1D the new core has been inserted into the channel
17 and it is rolling along the rolling surface 15 towards the nip
9, whilst the rotating element 23 of the weakening device 21 is
returned in its waiting position of FIG. 1A. Actually, the rotating
element 23 of the weakening device 21 is actuated and performs a
rotation by 360.degree. only once per winding cycle, i.e. for each
cycle of formation of a single log R. It is accelerated until it
achieves with its pad 25 a peripheral velocity substantially equal
to the feeding speed of the web material N along the feed path
thereof, i.e. a peripheral speed substantially corresponding to
that of the winding roller 3, around which the web material N is
driven and guided and which supports the web material N when it is
touched by the pad 25 to receive the liquid L.
[0046] The web material, wet along the weakening line with the
liquid L, continues to adhere to the winding roller 3, even if
greatly weakened, due to the liquid impregnating the cellulosic
fibers of which the web material N (typically tissue paper) is
made. In this way control of the web material N is maintained,
which is not completely severed following the weakening caused by
the liquid applied by the pad 25. The control of the web material
is further improved thanks to the fact that the liquid L, which has
impregnated the web material N along the weakening line, tends to
make the web material to adhere to the winding roller 3. This
latter can be coated, partially or completely, for example along
annular areas, with a material with a high friction coefficient, so
called "grip" material, which assures a further control on the web
material N and the transferring thereof along the feed path around
the winding roller 3.
[0047] In FIG. 1D the weakening line indicated with I is in a
position which is at least approximately phased with the position
of the new core A provided with the lines of glue RC1 and RC2 that
is rolling inside the channel 17. In the instant represented in
FIG. 1D the weakening line is upwards, i.e. before the core A
relative to the direction of feed of the web material N. As the
axis of the core A moves at a speed equal to the half of the speed
of feed VN of the web material, whilst the weakening line I
obviously moves with a speed VN, said weakening line I will pass
the winding core A, as shown in the subsequent phase represented in
FIG. 1E. Here the interruption line I is downstream (relative to
the direction of feed of the web material N) of to the new core A
that continues to roll on the surface 15 along the channel 17
towards the nip 9. By moving from the position of FIG. 1D to the
position of FIG. 1E the core A has transferred the glue C2, applied
by the second dispenser 33, to the area of the web material N
adjacent to the severing weakening line I towards the log R. In
this way, when the web material N will be interrupted along the
line I, the glue C2 will close the free tail end of the web
material forming the log R.
[0048] In the phase illustrated in FIG. 1E the line of glue RC1 is
in contact with the web material N due to the effect of the rolling
of the core A along the surface 15. In this way, also thanks to the
light pressure exerted between the core A and the roller 3 (due to
the fact that the channel 17 has a dimension slightly lower than
the diameter of the core A, which slightly deforms so as to advance
along said channel) the web material N is made to adhere to the
core A in correspondence of the line RC1 of glue. The adhesion
effect obtained, thanks to the glue C1, between the web material N
and the new core A, which continues to roll moving forward along
the channel 17, is sufficient to cause the breakage of the web
material along the weakening line I.
[0049] In fact, along this weakening line the web material, soaked
with liquid, has a very low tensile strength and substantially
looses its elasticity. The slight traction, to which the web
material N is subjected due to the effect of the relative movement
between the core A rolling on the surface 15 and the web material N
tending to rotate with the roller 3, causes tearing, i.e. complete
severing of the web material along the weakening line I. Tearing
practically occurs thanks to the fact that the trajectory of the
web material is altered by the presence of the winding core. When
the web material adheres to the core, and this latter rolls in the
introduction channel, the web material is forced to leave its
original trajectory (along the surface of the winding roller 3) and
starts to follow the surface of the winding core.
[0050] What is obtained is represented in FIG. 1F: the severing
position of the web material N is defined in an intermediate
position between the core A and the log R, with formation of the
tail end LC that, thanks to the glue C2, will adhere to the log R.
The interruption of the web material in the severing position
between the core A and the log R also causes the formation of the
head end LT that adheres to the core A, which, continuing to roll
on the surface 15 towards the nip 9 and thus entering into contact
firstly with the second winding roller 5 and subsequently with the
third winding roller 7, by continuing to rotate will cause the
formation of the new log R repeating the winding cycle and the
subsequent exchange cycle described above with reference to the
sequence of FIGS. 1A-1F.
[0051] For a better understanding of the mechanism for weakening
and subsequently severing the web material, FIGS. 1G to 1I
schematically show a plan portion of a web material N, on which are
represented the perforation lines P1, P2, P3, the weakening line I
and the severing line of the web material, generated as disclosed
above, with formation of the ends LC and LT.
[0052] More in particular, FIG. 1G shows a plan portion of web
material N winding on the log R. P3 indicates the perforating line,
in correspondence of which the liquid is applied to weaken the web
material forming the weakening line I, whilst P1 and P2 indicate
other perforating lines generated by the perforating unit 11. In
the subsequent FIGS. 1H and 1I it can be observed how the weakening
line moves towards the log winding area and then, in correspondence
of said area, the separation occurs generating the leading end LT
and tail end LC.
[0053] In view of what has, been described and illustrated above,
it should be understood that with the rewinding machine according
to the present invention the operation of severing the web material
is substantially subdivided into two phases: in a first phase the
weakening is performed along the line I of the web material by
means of the device 21. In a second phase the interruption is
accomplished, i.e. it is completed forming the leading and tail
ends LT, LC, exerting a very modest mechanical action sufficient to
overcome the remaining resistance of the cellulosic fibers of the
web material N in correspondence of the weakening line I. As
indicated above, this interruption is also obtained simply due to
the effect of the traction exerted on the web material N by the
glue, which makes the head end LT to adhere on the new core A
inserted in the machine. In this way it is not necessary to have
expensive additional members for cutting or severing the web
material. The whole rolling channel 17 remains devoid of mechanical
members and the portion of web material between the leading end LT
and the adhesion or anchoring point in correspondence of the line
of glue RC1 is extremely short, thus obtaining a very regular
winding without creases also of the first part of web material N of
each log R.
[0054] FIG. 2 shows a modified embodiment of the rewinding machine
according to the present invention. The same numbers indicate same
parts as, or equivalent parts to, those of the embodiment shown in
FIGS. 1A to 1F.
[0055] In this embodiment the weakening device 21 comprises again a
rotating element 23, which, however, does not receive the liquid L
from a tank, but projects it through a nozzle carried at the distal
end of the rotating element 23, so as to form an adequately shaped
jet G of liquid, or a plurality of jets arranged side by side.
These jets wet the web material N, thus forming the weakening line
I. In order to obtain an easier synchronization and to avoid that
the weakening line I is produced with an excessive dimension in the
direction of the longitudinal development of the web material, to
the rotating element 23 screens 24A, 24B can be associated, between
which a slot is defined, developing nearly parallel to the axis of
the winding roller 3. In this way the jet or jets G of liquid L
generated by the nozzles carried by the rotating element 23 wet an
area I of very limited dimensions.
[0056] FIG. 4 shows a rewinding machine according to the present
invention in a further modified embodiment. The same numbers
indicate parts identical or equivalent to those in FIGS. 1A to 1F.
In this embodiment the pad 25 is wet through contact with a
distributor comprising a rotating roller 30, whose surface is
continuously wet by means of a dispenser 32. The surface of the
rotating roller 30 can be machined, for example to provide a series
of micro-cavities, so as to hold the water or other liquid to be
transferred to the pad 25.
[0057] Even if the weakening obtained through the application of a
liquids is particularly advantageous as, among other things, it
allows to maintain a better control of the web material that thanks
to the liquid tends to adhere to the roller 3 in a manner
sufficient not to detach due to the effect of the ventilation
caused by the rotation of the roller 3, in other embodiments the
weakening line can be generated mechanically or pneumatically. At
this end nozzles can be provided inside the winding roller 3, which
generate air flows in an angularly preset position in
correspondence of the weakening line I. Alternatively, the air
flows can be generated by an external system, similar to that
represented by the element 23 in FIG. 2. In other further
embodiments the weakening device can be of the mechanical type.
FIG. 3 shows a schematic embodiment, wherein a mechanical
arrangement is adopted for generating the weakening line. In this
figure again, parts equal or equivalent to that of the previous
embodiments are indicated by the same reference numbers. In this
embodiment the severing device 21 comprises a rotating element 23,
at the end of which a toothed blade or some other element is
applied, which can perform a partial cut in cross direction of the
web material N. The blade, indicated with 23X, cooperates with a
counter-blade 26 associated to the winding roller 3. In some
embodiments the counter-blade 26 can be arranged in a fixed
position relative to the winding roller 3, and it can be therefore
integral with the winding roller 3. This arrangement, however, has
the great disadvantage of lacking flexibility in the operation of
the machine, in particular as the position, in which the weakening
line is formed, is constrained and it cannot be changed at will, as
the counter-blade 26 is an integral part of the roller 3 and
rotates together therewith.
[0058] In a different embodiment, shown in FIG. 3, the
counter-blade 26 is carried by a flexible member 28 driven around
the winding roller 3 and a further roller or series of pulleys 28X.
The flexible member can move independently of the winding roller 3,
being formed for example by a plurality of belts driven around
guide pulleys coaxial to the roller 3, this latter being formed by
a plurality of axially aligned sections. Such a configuration is
known for other purposes and it is described for example in
WO-A-2008/050370, to which reference should be made for greater
construction details. In this way the counter-blade 26 can be
brought in an active position opposite to the rotating element 23
only when it is necessary, i.e. during the exchange phase. As the
counter-blade 26 is in this case provided with a movement which is
independent of the rotation movement of the winding roller 3, it
can be positioned in any instance in the working position and
cooperate with the blade 23X of the weakening device 21 in any
desired instant during the winding cycle. In this way a flexible
machine is obtained, wherein the length of each log R can be chosen
at will without constraints relative to the diameter of the winding
roller 3.
[0059] Both in the configuration of FIG. 3 and in the configuration
of FIG. 2 the principle remains valid of severing the web material
in two phases: a first weakening phase with formation of the
weakening line I and a second phase of complete severing, between
the two phases the web material N being controlled and transferred
around the roller 3 from the position (defined by the weakening
device 21), in which the weakening line I is generated, and the
severing position, in which the leading end LT is completely
separated from the tail end LC.
[0060] The glue C1 for anchoring the leading end of the web
material on the new core A is usually a more sticky glue, i.e. a
glue harder than the glue C2, with which the tail end LC is
anchored to the log R in order to seal it. In other embodiments the
tail end LC can be closed by the adhesion effect given by the same
liquid L applied by the weakening device 21, for example providing
that the liquid L is a water solution also with high dispersion of
an adhesive or glue. The quantity of glue in the liquid L and the
quantity of liquid L applied to the web material N will be
determined in such a manner as to avoid dirtying of the winding
roller 3.
[0061] The use of a glue on the winding core, in order to make the
leading end of the web material N adhere on the winding core
following severing, is particularly advantageous as in this way
there is no need for additional members for cutting or severing or
tearing the web material: the weakening along the line I is
sufficient to cause tearing of the web material due to the
retention effect of the glue C1 on the core A.
[0062] Moreover, the concept upon which the invention is based can
be implemented, although with lesser advantages, also in machines
wherein a glue is not used, or wherein the glue is not sufficient
to obtain tearing or complete interruption of the web material
following the weakening thereof. For example, the web material can
start the winding around the tubular core A due to the effect of
electrostatic adhesion, through air flows or in any other manner,
avoiding the application of glue on the winding cores. This is
particularly useful when the winding cores are subsequently
extracted from the log, which in this case will be a coreless log.
In these cases, and also when the used glue has not sufficient
adhesive power to cause the tearing of the web material weakened
along the weakening line I, severing of the web material can be
obtained in other manner.
[0063] In some embodiments interruption can be obtained for example
by temporarily accelerating the upper winding roller 7, so as to
cause a tension in the web material. This tearing system is already
used in prior art machines. It however has the disadvantage that
the high resistance and elasticity of the paper requires great
accelerations of the movable winding roller. In fact, it is
necessary to tension the paper or other web material N, with very
modest accelerations, beyond the breakage limit thereof in order to
obtain tearing along the weakening line, for example along a
perforation line. In absence of other measures, also due to the
elasticity that these materials (typically tissue paper) present,
it is necessary to use very powerful and over dimensioned motors,
able to accelerate in a very sudden manner to control the rotation
movement of the winding roller 7.
[0064] By using the concept upon which the present invention is
based, the previous weakening of the web material along a weakening
line, along which the severing will be subsequently performed,
allows on one hand to maintain the control of the web material N
until the weakening line I is brought downstream (relative to the
direction of feed of the material N) relative to the new winding
core, and at the same time to obtain the tearing or severing of the
material with much more modest accelerations of the winding roller
7, independently of the presence of the line of glue on the core.
Furthermore, a high accurateness is not necessary in the position
of the weakening line relative to the moment in which the roller 7
is accelerated.
[0065] In other embodiments, severing can be for example obtained
by means of air flows generated by nozzles arranged in annular
grooves of the winding roller 3 or housed inside this latter,
which, in this case, can be provided with a series of perforations,
through which the pressurized air flows pass, which cause tearing
of the web material. In this case again the weakening made by the
device 21 eases and facilitates tearing, which can occur with much
more modest air pressures and therefore with advantages in terms of
energy and of reduction of noise during operation of the
machine.
[0066] In some embodiments, the winding roller 3, around which the
web material N is driven and with which the web material remains
into contact after it has been wet, can be processed so as to avoid
that the web material N (generally constituted by tissue paper with
one or more plies) remains adhering to the roller due to the effect
of moistening. FIG. 5 schematically shows an enlargement of a
portion of the surface of the roller 3 in a configuration in which
the roller is knurled, i.e. it is worked to form engraving or
cavities I and protuberances P which reduce the contact surface
with the web material N.
[0067] In other embodiments a system can be provided for
facilitating the detachment of the web material N from the roller 3
and/or facilitating the start of the winding of the web material N
around the winding core A. FIGS. 6A to 6D show an operative
sequence of an improved rewinding machine, wherein an auxiliary
system is provided for detaching the web material N from the roller
3. The same numbers indicate the same or equivalent parts to those
of the previous embodiments, which will be not described in detail.
In this embodiment the machine has only one glue dispenser 33,
which applies only one line of glue RC2 on the tubular cores A. To
the glue dispenser 33 a transferring device 39 is associated, which
sequentially inserts the cores A in the channel defined between the
rolling surface 15 and the outer cylindrical surface of the roller
3.
[0068] In this embodiment the roller 3 has a cylindrical shell
perforated with holes 3F, preferably distributed along the whole
circumferential development of the roller. Inside the roller 3 a
casing 3C is provided, inside which pressurized air is inserted and
from which the pressurized air exits towards the inner cylindrical
surface 3S of the roller 3. In this way it is possible to generate
an air flow through the holes 3F of the roller 3. The angular
position of the casing 3C, and consequently the angular position f
the air flow, can be changed or adjusted according to the
requirements and the conditions of operation.
[0069] Downstream of the area where air is blown from the roller 3,
and upstream of the nip 9 between the winding rollers 3 and 5, an
oscillating member 6 is arranged, hinged around ax axis 61A of
oscillation and carrying, at its end, a plurality of nozzles 63 for
blowing air, aligned according to a cross direction, i.e.
orthogonally to the plan of the figure.
[0070] The operation of this machine is clearly illustrated by the
sequence of FIGS. 6A to 6D. The core inserter 39 picks up a core A
from the glue dispenser 33, which has already applied a line of
glue RC2 on the core A in such a position that the glue is
transferred on the free tail end of the log R under forming in the
rewinding machine. The core picked up by the inserter 39 is
inserted in the channel 17 (FIG. 6B), coming into contact with the
rolling surface 15 and with the web material N driven around the
roller 3. The core starts to roll until the glue line RC2 comes
into contact with the web material N and at least a part of the
glue is transferred to it. The synchronization is such that the
glue is transferred to the web material in the area directly
downstream of the weakening line I generated by the device 23, 25,
preferably at a perforation line, as described above. The core A
continues to roll towards the area where the blowing casing 3C is
arranged. The operation is synchronized in such a manner that when
the core is near the blowing casing 3C, the weakening line I is
nearly in front of the casing 3C. In this phase an air flow is
generated, which causes the tearing of the web material N along the
weakening line I and the detachment thereof from the surface of the
winding roller 3 (FIG. 6C). The air flow tends also to push the
initial free end LI, which has been therefore formed, towards the
new core A. The humidity absorbed by the web material in
correspondence of the initial free end LI can be sufficient to
obtain the adhesion of the material N to the new core and therefore
the start of the winding. In order to increase this adhesion effect
the weakening line can be formed using glue added to the water. The
core, continuing to roll towards the nip 9, starts to be wrapped in
the web material so as to start the new winding cycle. Preferably,
as illustrated herein, the air flow is actuated only after that the
core A pinched the web material N against the winding roller 3, so
as to avoid a premature detachment of the web material N from the
roller 3 or for a excessively long segment.
[0071] When the core A passes in the area where the device 61 is
arranged, and overtakes it, this latter is made to oscillate in
clockwise direction so as to generate an air flow through the
nozzles 63, which facilitates the winding of the first turn of web
material, in addition to the mechanical effect due to the rotation
of the device 61 (FIG. 6D).
[0072] In some embodiments the device 61 can be omitted. In other
embodiments, it can be replaced for example with a system of fixed
nozzles, for example arranged with different angulations, and
actuated sequentially so as to direct towards the initial free end
LI an air flow oriented so as to facilitate the winding of the
first turn of web material.
[0073] In some embodiments the system for blowing air from the
inside toward the outside of the roller 3 can be combined with a
system for applying double glue, as provided in the embodiments
previously described, to apply glue both to the final end and to
the initial end of the web.
[0074] It is also possible to omit the gluing of the core A
completely, and to glue the final tail end LC outside of the
rewinding machine with a sealer of the traditional type, whilst the
adhesion of the initial free end LI on the core A is assured by the
liquid applied along the weakening line I.
[0075] It is understood that the drawing only shows an example
provided by way of a practical arrangement of the present
invention, which can vary in forms and arrangements without however
departing from the scope of the concept underlying the invention.
Any reference numbers in the appended claims are provided for the
sole purpose of facilitating reading of the claims in the light of
the description and the drawing, and do not in any manner limit the
scope of protection represented by the claims.
* * * * *