Technical field
[0001] The present invention relates to a machine for producing rolls of web material wound
around winding spindles.
[0002] Machines of this type are used for example to produce rolls or reels of paper, tissue-paper,
non-woven fabric and other web or sheet material.
[0003] Winding machine is usually intended as a machine which receives the web material
from a production machine upstream and winds it to form a roll or reel of large diameter.
Rewinding machine is usually intended as a machine which receives web material from
a roll or reel with a large diameter and rewinds it into rolls of a smaller diameter.
In both cases the web material may be cut longitudinally in continuous strips, with
which several rolls are formed in parallel simultaneously on the same spindle. The
term roll or reel is intended, in the context of this document, both as a whole roll
or reel and as a series of coaxial rolls placed side by side on the same winding spindle.
[0004] Unless otherwise specified, spindle must be- generically intended as a spindle made
of metal or another suitable material, or an assembly composed of a rod or spindle,
positioned and clamped on which are one or more cores in cardboard or another material,
typically non-electrically conductive material.
[0005] More specifically, the invention relates to a peripheral winding or rewinding machine,
that is in which the roll being formed is maintained in rotation by one or more moving
elements in contact with the external surface of the roll. Typically, the element
or elements which transmit, through friction, the rotating movement to the roll being
formed are composed of one or more winding rollers or cylinders.
[0006] The invention also relates to a new method for producing, in particular with a peripheral
winding procedure, rolls or reels of web material.
State of the art
[0007] In production of this type of roll, one of the critical aspects is constituted by
the initial winding phase, that is the operation through which the initial free end
of the web material, produced by the interruption of said material, starts to be wound
forming the first turn around a new winding spindle.
[0008] Frequently, the initial free end of the web material is made to adhere to the winding
spindle (or more precisely to tubular cores made of cardboard or another suitable
material, such as plastic or the like, positioned and clamped on an inner metal spindle)
by applying an adhesive. This makes it necessary to provide a gluing unit which applies
the adhesive to the cores or to the spindle prior to insertion in the winding zone.
The presence of adhesive in winding or rewinding machines represents a considerable
disadvantage as, in addition to the costs deriving from the consumption of adhesive,
it inevitably soils the various mechanical parts of the machine and its products.
The presence of adhesive is unacceptable in some types of reels, such as those destined
for producing hygiene articles such as medical products, diapers and sanitary towels.
[0009] In other prior art machines the initial free end is wound, to form the first turn
around the spindle, with the aid of jets or air. This method also has some disadvantages.
In the first place, the use of jets of air requires the presence of nozzles and a
compressed air line, with the consequent plant layout cost and cost deriving from
power consumption to supply the compressed air. The use of compressed air increases
the noise of machines and, moreover, does not guarantee reliable and regular start
of winding. In particular, when several strips of web material are wound in parallel
on aligned tubular cores, the use of compressed air may cause the head of the strips
to veer to the side, thus causing them to overlap with the consequent problems during
production.
[0010] In some applications, the initial free end of the web material is made to adhere
to the winding spindle with an electrostatic system. This technique charges the web
material electrostatically immediately prior to cutting, producing a difference in
electric potential between the web material and the winding spindle. This difference
in potential attracts the web material towards the spindle causing the former to adhere
to the latter and thus commencing winding of a new roll.
[0011] This technique is frequently used in winding or rewinding machines of the central
type, that is where the winding movement is imparted directly to the spindle, instead
of through a peripheral winding system. Examples of the use of electrostatic charges
to make the web material adhere to the winding spindle in a central winding system
are described in the patent USA 4.852.820, the patent USA 5.823.461, the patent USA
5.845.867 and the patent USA 6.264.130.
[0012] In peripheral type rewinding or winding machines the application of this technology
is more difficult, for the reasons set forth below. Peripheral rewinding machines
are currently preferred for several reasons, linked both to the improved operation
of these machines and to their higher production level. Examples of rewinding machines
to which the present invention may be applied are described in the patent USA 4.422.588,
the publication WO-A- 99/02439 and the publication WO-A- 00/61480.
[0013] Electrostatic bars are used to electrostatically charge the web material, that is
electrically conductive bars connected to an electric voltage source. These are commonly
employed to ensure correct start of winding of the new roll on winding machines that
do not have rollers in contrast with the winding spindle (as is typically the case
in central winding or rewinding machines), or that have a single roller contrasting
the reel or winding spindle.
[0014] When the winding or rewinding machine is constructed so as to present one or more
rollers in contact with the spindle in the initial phase to form a new roll, there
is the risk of the web material not being wound correctly around the spindle. If,
in fact, the initial end of the web material during its first turn (that is while
forming the first turn of material around the spindle) is in contact both with the
winding spindle and the contrast roller in the same point, it may detach from the
spindle and adhere more firmly to the contrast roller.
[0015] If the geometry of the machine allows the free end of the web material, electrostatically
charged, to adhere alternatively to the spindle or to the contrast roller, it will
adhere to the element with a greater electric capacitance.
[0016] Usually, the contrast or winding rollers, in contact with the winding spindle and
with the roll being formed, have larger dimensions than the spindle and, unlike the
spindle, are not coated with non-conductive material, while the winding cores, made
of cardboard or another non-electrically conductive material, are normally positioned
on the spindle. This means that the contrast or winding rollers have a greater capacitance
than the spindle. As a result the web material tends to adhere, with its initial free
end, to the contrast or winding roller instead of to the spindle. When this occurs
the machine must be stopped and the web material which has wound around the roller
must be removed before restarting production. This causes a waste of material and
considerably long machine idle times with consequent loss of production.
Objects and summary of the invention
[0017] The object of the present invention is to produce a winding or rewinding machine
which does not have the aforesaid disadvantages and allows each roll to be initially
wound around the winding spindle easily and securely, by using electrostatic systems
to make the initial free end of the web material adhere to the winding spindle, or
to the winding cores present on the spindle.
[0018] These and other objects and advantages which shall become clear to those skilled
in the art by reading the text below, are obtained in substance according to the invention
by a rewinding or winding machine of the type comprising in combination: at least
a roller in contact with the winding spindle in the initial phase of winding the web
material around the spindle; a cutting element to cut the web material at the end
of winding a roll and form an initial free end for winding a subsequent roll around
a new winding spindle. Characteristically, according to the invention at least an
electrostatic bar is provided to electrostatically charge the web material, and the
roller in contact with the spindle is made at least partially in non-electrically
conductive material. As specified above, in this context spindle is intended as a
whole as the assembly composed of the actual rod or spindle and by any tubular core
positioned and temporarily clamped on the spindle and around which the web material
is wound. Therefore, roller in contact with the spindle is generically intended as
the roller which comes into contact with the surface of the actual spindle when it
has no tubular core positioned on it, or the roller which comes into contact with
the external surface of the tubular core positioned on the rightly called spindle,
which remains inside the tubular cores.
[0019] By producing at least the cylindrical surface of the roller in contact with the winding
spindle in non-electrically conductive material, the electrical capacitance of the
roller is reduced drastically, so that the initial free end produced by cutting the
web material adheres securely to the winding spindle, or to the cores positioned on
the spindle, allowing secure and reliable start of winding and avoiding the risk of
the material being wound around the roller instead of around the spindle.
[0020] Although it is possible to reduce the electric capacitance of the roller in contact
with the winding spindle by a coating of non-conductive material which covers, with
an adequate thickness, the cylindrical surface of the roller, it is preferable to
produce the whole cylindrical wall of the roller with said material, for example in
the form of a cylindrical sleeve, at the ends of which metal roll ends, for example
made of steel, are connected, with the supporting shanks or pins also made of steel.
The non-conductive material may for example be a synthetic resin reinforced with glass
fibers or other non-conductive fibers, in Kevlar or the like, although it is also
possible to use different materials, as a function of the characteristics of mechanical
resistance and the dimensions that the roller must have.
[0021] The roller in contact with the winding spindle, made in non-electrically conductive
material, may be a winding roller that remains in contact with the roll being formed
around the spindle substantially for the entire winding cycle of the roll. For example,
in a rewinding machine comprising two winding rollers defining a winding cradle on
which the roll being formed rests, one of the two winding rollers may be made of non-conductive
material, or at least coated with this material on its cylindrical surface.
[0022] In a rewinding machine of this type, according to a particularly advantageous embodiment
of the invention, the electrostatic bar and the cutting element are mounted on an
assembly oscillating around the axis of rotation of a first of said winding rollers,
with at least the second of said winding rollers being made at least partially of
non-electrically conductive material.
[0023] According to a different embodiment of the invention, the machine may be a winding
machine, or a so-called winder or reeler, provided with a support for the winding
spindle, and on which the winding spindle and the roll being formed around said spindle
are maintained in rotation by said winding roller, around which the web material is
driven.
[0024] A machine with this configuration may be provided with a moving assembly carrying
the cutting element and the electrostatic bar, said assembly performing a rotating
or oscillating movement around the axis of the winding roller to insert a winding
spindle, cut the web material and fasten the web material around said winding spindle.
A machine of this type may cut the web material and commence winding without interrupting
feed of the web material, that is at a more or less constant and in any case continual
feed speed.
[0025] In a different embodiment the machine comprises a support for the winding spindle,
a winding roller in contact with the roll being formed, to maintain the roll in rotation
while it is being formed, a moving assembly carrying the electrostatic bar, the cutting
element and the roller in contrast with the spindle, in non-electrically conductive
material. This roller may be provided with a movement in relation to the moving assembly
which draws it towards and moves it away from the winding spindle.
[0026] The object of the invention is also to provide a winding method which makes it possible,
in a reliable and secure manner, to start winding the various rolls on the winding
spindles using an electrostatic system to make the initial free end adhere to the
winding spindle.
[0027] Therefore, according to a different aspect, the invention relates to a method for
producing rolls of web material wound around a winding spindle, comprising the steps
of:
- winding a first roll of web material around a first winding spindle;
- bringing a second winding spindle in contact with the web material;
- cutting the web material, in proximity to said second winding spindle to form an initial
free end and a final free end of web material;
- winding the initial free end of the web material around said second spindle and starting
to wind a second roll, said web material being retained, in proximity to said initial
free end, between said second winding spindle and said roller;
characterized in that said roller is formed in non-electrically conductive material.
[0028] In particular, the roller made of non-conductive material may be a winding roller,
said rolls being wound with a peripheral winding system.
[0029] Further advantageous characteristics and embodiments of the method and of the machine
according to the invention are indicated in the attached dependent claims.
Brief description of the drawings
[0030] The invention shall now be better understood according to the description and the
attached drawings, which show non-limiting practical embodiments of the invention.
In particular, in the drawing:
Fig. 1 shows an overall view of a rewinding machine to which the invention is applied;
Fig. 2 shows an enlarged detail of the nip between the winding rollers in which winding
of each roll commences;
Fig. 3 shows an overall view of a winding machine to which a second embodiment of
the present invention is applied;
Fig. 4 shows a view analogous to the view in Fig. 3 in a different position of the
machine elements;
Fig. 5 shows an enlargement of the zone in Figs. 3 and 4 in which winding commences
on the machine;
Fig. 6 shows a schematic side view of a different winding machine to which the invention
is applied;
Fig. 7 shows a side view analogous to the view in Fig. 6, in a different machine layout;
and
Fig. 8 shows an enlarged detail of the zone in Figs. 6 and 7 in which winding commences
on the machine.
Detailed description of the preferred embodiments of the invention
[0031] Figs. 1 and 2 show a first application of the underlying concept of the invention
to a so-called rewinding machine and more specifically a peripheral rewinding machine
of the start-stop type.
[0032] The rewinding machine, generically indicated with 1, receives from a reel with a
large diameter, indicated with B, a web material N which is rewound on rolls with
a smaller diameter, indicated with R. The rewinding machine comprises two winding
rollers 3, 5 which define a winding cradle 7, in which the rolls R are formed. After
these rolls have been formed they are unloaded onto a carriage indicated with 9, which
picks up each roll and transfers it towards an unloading zone. The web material N
is fed into the winding cradle passing through a nip between the two winding rollers
3, 5, under which, in a per se known manner, an assembly of cutting blades 11 are
positioned to divide the web material N into individual longitudinal strips, each
of which is wound onto a respective core made of cardboard or another suitable material,
positioned axially on a metal spindle. In practice, therefore, in this case the roll
R may be formed of a plurality of rolls of a shorter axial length aligned with one
another along the axis of the winding spindle.
[0033] The enlarged view in Fig. 2 shows a metal spindle 13 and a winding core 15 mounted
axially on the spindle. In a per se known manner, the metal spindle 13 is expandable
to clamp the various cores 15 on it in the desired position. It is also possible for
a single winding core to be positioned on a single spindle 13 and in this case the
web material N is not divided into longitudinal strips by the blades of the assembly
11.
[0034] In the layout in Fig. 1, the rewinding machine 1 has just finished winding a roll
R, which has been unloaded onto the carriage 9, while the web material N has not yet
been cut to start winding a subsequent roll. To cut the web material N and start winding
a new roll around the new spindle which, in a per se known manner, has been placed
in the cradle between the winding rollers 3 and 5, a unit or assembly indicated as
a whole with 17 is provided, hinged around the axis 3A (Fig. 2) of the winding roller
3.
[0035] The assembly 17, as shown in the detail in Fig. 2, comprises a transverse cutting
element, indicated with 19, operated by a piston-cylinder actuator 20. Positioned
adjacent to the transverse cutting element 19 is an electrostatic bar 21, connected
to a high voltage source, not shown. The voltage of the bar 21 may typically reach
60 kV.
[0036] Also positioned on the assembly 17 is a guiding roller 23, and a curvilinear section
bar 25. As shown in the representation in Fig. 2, by rotating the assembly 17 clockwise
from a downward position out of sight under the winding rollers 3, 5 to a position
raised above the winding cradle 7, the still integral web material N which extends
between the completed roll R and the spindle 13 inserted in the winding cradle 7 to
start winding the new roll, partially encircles the assembly 17, as it is driven around
the guiding roller 23 and around the section bar 25. A portion of web material is
thus held in tension between the edge of the section bar 25 and the nipping point
between the spindle 13 and the winding roller 3. This portion of web material N is
charged electrostatically by the electrostatic bar 21 and cut by the transverse cutting
element 19. The electrostatic bar can start to electrostatically charge the web material
before its feed is interrupted, so that an adequately long portion of material is
electrostatically charged.
[0037] The final free end which is formed by cutting remains on the finished roll R, while
the initial free end must be fastened to the spindle 13, or more precisely to the
tubular cores 15 positioned and clamped on this, to start winding the new roll. For
this purpose, electrostatic charges have been applied to the web material by the electrostatic
bar 21. In order for the initial free end to wind correctly around the spindle 13,
instead of around the winding roller 5, the latter is made of non-electrically conductive
material, typically in resin reinforced by glass fibers. As, on the other hand, the
spindle 13 is metal and is electrically grounded, that is at zero potential, the free
end of the web material adheres to the spindle through electrostatic effect and is
drawn by the rotatory movement of the spindle to form the first turn. Once the first
turn has been formed, the web material is firmly fastened to the spindle.
[0038] The winding roller 3 may be made, as is traditionally the case, of electrically conductive
metal. This is possible as the specific position in which the initial free end of
the web material is produced means there is no risk of its adhering to the roller
3 instead of the winding spindle 13.
[0039] Figs. 3, 4 and 5 show a winding machine or reeling drum to form rolls or reels R
of web material N, for example fed directly from a production machine. With initial
reference to Figs. 3 and 4 the machine, indicated as a whole with 41, comprises a
pair of supporting surfaces 43 resting on which time by time with its ends is a winding
spindle 45, around which a roll R of web material N is formed. The spindle around
which the roll or reel is being formed is retained by two pairs of rollers 47 carried
by slides 49 which translate on guides parallel to the supporting surfaces 43 to retain
the winding spindle 45 and the roll being formed in contact with a motor-driven winding
roller 51 which rotates around a fixed axis of rotation 51A. The web material N to
be wound is driven around the winding roller 51, which also transmits, through friction,
movement to the roll being formed.
[0040] Other winding spindles 45, positioned and clamped on which are tubular cores in cardboard
or another non-electrically conductive material, are found standing-by above the winding
zone and are inserted one by one in the zone in which winding commences by a mechanism
illustrated in Figs. 3 and 4. This mechanism comprises an oscillating unit 55 hinged
around an axis 57 and controlled by a piston-cylinder actuator 59. In a per se known
manner, the unit 55 picks up, with the aid of a gripping jaw 61, the individual spindles
45 and, through an oscillating movement around the axis 57, brings them adjacent to
the winding roller 51 and resting on the surfaces 43.
[0041] In this and in the subsequent examples it must be understood that the spindles may
also be used without tubular cores positioned on them. In this case, as well, it is
advantageous to use a roller in non-conductive material, although the spindle is conductive
and therefore designed to attract the electrically charged free end of the web material.
In fact, in general these spindles normally have smaller dimensions and masses to
the adjacent winding or driving rollers, and therefore have a lower electrical capacitance
if these rollers are made of metal.
[0042] An assembly 67 oscillates around an axis parallel to the axis 51 A of the winding
roller 51, controlled by an electric motor 62, with crown gear and pinion transmission
63, 65. The assembly 67 carries: a transverse cutting element 69, an electrostatic
bar 71 and a contrast roller 73. The contrast roller 73 is mounted on a pair of sides
75 hinged to the assembly 67 and oscillating in relation to this controlled by a piston-cylinder
actuator 77. A second piston-cylinder actuator 79 controls the movement of the transverse
cutting element 69. The assembly 67 also supports a pair of guiding rollers 80 and
81.
[0043] During winding of a roll or reel R, the spindle 45 on which the roll is being formed
is held in contact with the winding roller 51 by the slide 49 and the rollers 47 mounted
on this. A new spindle 45, on which the next roll will be formed, is in the meantime
positioned on the unit 55. When the roll R is almost completed, it is moved away from
the winding roller 51, while the new spindle engaged by the unit 55 is transferred,
by a clockwise oscillating movement around the axis 57 of the unit 55, to the zone
in which winding commences, in contact with the surface of the winding cylinder 51.
[0044] Simultaneously the assembly 67 is made to oscillate counter-clockwise around its
axis of oscillation to be inserted between the new spindle 45 lowered by the unit
55 and the roll R just formed. The oscillating movement of the assembly 67 causes
a loop of web material N to form, driven around the new spindle 45 and the guiding
rollers 80 and 81. The unit 55 and the assembly 67 are moved without requiring to
stop feed of the web material, although slowing of the feed speed is not excluded.
When the assembly 67 is in the cutting position, to produce - through the transverse
cutting element 69 - the initial free end of the new roll, the contrast roller 73
is brought into contact with the new spindle 45, so that the web material N is nipped
on one side between the winding roller 51 and the newly inserted spindle 45 and on
the other side between this spindle and the contrast roller 73. The electrostatic
bar 71 electrostatically charges the web material before it is cut by the cutting
element 69 operated by the piston-cylinder actuator 79. Once the element 69 has performed
the transverse cut on the web material, the final free end is wound on the finished
roll R, while the initial free end will start to wind around the new spindle 45. Initial
winding is guaranteed by electrostatic attraction between the web material electrostatically
charged by the bar 71 and the metal part of the spindle 45, which is at zero potential.
[0045] To prevent the web material from starting to wind, with its initial free end, around
the contrast roller 73, this is made of non-electrically conductive material. The
electric capacitance of the spindle 45 is thus sufficient to guarantee adhesion of
the free end of the web material produced by the cut performed by the element 69.
After the first complete turn has been formed around the winding spindle 45, the assembly
67 may be removed from the winding zone through a clockwise oscillating movement and
the spindle 45 may be engaged at its ends by rollers 47 carried by the slides 49 on
the sides of the machine. Winding continues in these conditions until completion of
the subsequent roll.
[0046] Just as in the previous example of embodiment, the machine represented in Figs. 3
and 5 is also provided with a longitudinal cutting assembly, indicated schematically
with 78, to divide the web material N into a series of longitudinal strips narrower
in width to the overall width of the web material. When the web material is cut longitudinally,
the various strips are wound on tubular winding cores positioned beside one another
on the single spindle 45. In this case the roll or reel B will actually be formed
of a series of rolls of a shorter axial length positioned side by side.
[0047] Figs. 6, 7 and 8 show a modified embodiment of a reeling drum or winding machine
which, analogously to the machine shown in Figs. 3, 4 and 5, is capable or performing
the exchange phase, i.e. unloading the completed roll, inserting the new spindle and
starting to wind a new roll on said spindle without interrupting feed of the web material.
[0048] In this embodiment, a supporting surface 101 is provided on which a winding spindle
103 rests to form a roll or reel R around it. Also in this case the roll or reel R
may actually be constituted by a plurality of rolls with a shorter axial length positioned
on the same spindle. Rollers 105 carried by oscillating arms 107 hold the roll being
formed R in contact with a winding roller 109, around which the web material to be
wound, indicated with N, is fed. A longitudinal cutting assembly 111 is provided to
divide the web material into continual longitudinal strips if so required.
[0049] While a roll or reel R is being formed, carried in rotation by the winding roller
109, a new winding spindle 103 is engaged by a pickup system 113 of a per se known
type (Fig. 7).
[0050] An assembly indicated as a whole with 115, rotates around the axis 109A of the winding
roller 109, and is used to cut the web material and start winding a new roll around
a new winding spindle 103 inserted in the winding zone by the pickup system 113. The
assembly 115 is shown in detail in Fig. 8. It comprises a transverse cutting element
constituted by a blade 117 mounted oscillating around an axis 119. The oscillating
movement is controlled by a piston-cylinder actuator 121, the cylinder of which is
mounted oscillating by a bracket 123 on the oscillating assembly 115. Mounted at the
sides of the axis of oscillation 119 of the blade 117 are two guiding rollers 125
and 127, between which a curved section bar 129 is positioned. An electrostatic bar
131 is mounted under the guiding roller 125.
[0051] The machine shown in Figs. 6 and 8 performs the exchange, i.e. replacement of a complete
roll or reel R with a new winding spindle 103, in the following way. Without interrupting
feed of the web material, while the roll R is completed maintaining it in contact
with the winding roller 109, the assembly 115 rotates clockwise from the position
in Fig. 7 to position itself between the web material N being fed to the roller 109
and the roller itself. The clockwise rotatory movement continues until reaching the
angular position in Fig. 6, before the unit 113 moves from the position in Fig. 7
to the position in Fig. 6 with clockwise oscillation. Insertion of the new spindle
103 in the position in Fig. 6, in which winding of a new roll commences, thus occurs
subsequently to movement of the assembly 115 beyond the insertion position of the
new spindle 103.
[0052] When the assembly 115 and the unit 113 have reached the position in Fig. 6, the web
material is cut and transferred to the new spindle. In the layout in Fig. 6 a loop
of web material N is formed around the assembly 115, being driven on the two guiding
rollers 125, 127 and on the curved section bar 129. Before operating the transverse
cutting element 117, the electrostatic bar 131 starts to electrostatically charge
the web material. By operating the cutting element 117 an initial free end of the
web material is produced which adheres to the external surface of the new winding
spindle 103 positioned in contact with the winding roller 109, with the web material
interposed between said spindle and said roller. Adhesion through electrostatic effect
of the initial free end to the spindle instead of the winding roller 109 is guaranteed
by the fact that in this case the winding roller 109 is made of non-electrically conductive
material. The electrical capacitance of the winding spindle 103 is thus sufficient
for the web material to adhere to it, notwithstanding the presence of any winding
cores in non-conductive material positioned on the metal spindle 103 or in any case
notwithstanding the low electric capacitance of the spindle.
[0053] Upon completion of adhesion of the initial free end to the new winding spindle 103,
the assembly 115 starts rotation in the clockwise direction again, to return to the
position in the layout in Fig. 7, thus completing a rotation of 360°, while the roll
formed is removed through oscillation of the arms 107. The new winding spindle with
the new roll being formed is inserted in the space thus made available. This spindle
is then engaged by the rollers 105 as soon as they have been freed of the completed
reel and are returned with a counter-clockwise rotation of the arms 107. The pickup
system 113 moves upwards with counter-clockwise oscillation to engage a new winding
spindle which will replace the one inserted previously after the new roll has been
wound.
[0054] The use of a winding roller 109 made at least partly of non-electrically conductive
material makes it possible to cut the web material in a much more advantageous position
to the one in machines of this type currently employing electrostatic systems to make
the free end adhere to the new spindle. In fact, in prior art machines, to prevent
the initial free end from winding around the winding roller instead of around the
new spindle, it is necessary to produce ― during the final phase of winding the reel
and before the web material is cut ― a loop which surrounds the new spindle 103 by
about 180°. In substance, the trajectory of the web material extends around the roller
109, around a guiding roller in an analogous position to the roller 125 in Fig. 8
and also around one or more guiding rollers positioned further back towards the zone
from which the web is fed in relation to the position of the new spindle. The cut
must then be made in a position further back in relation to the spindle so that the
free end adheres to this under the effect of electrostatic attraction produced both
by the spindle and by the winding roller.
[0055] This known configuration is particularly unfavorable due to the great number of guiding
rollers and the twisted path which the web material must follow before being cut,
with consequent excessive stress of the material.
[0056] It is understood that the drawing only shows possible embodiments of the invention,
which may vary in form and layout without however departing from the scope of the
concept underlying the invention. The presence of any reference numerals in the attached
claims are provided purely to facilitate reading in the light of the description above
and the attached drawings, but do not limit the scope of protection thereof.
1. A winding or rewinding machine to wind a web material (N) and form a roll (R) around
a winding spindle (13; 45; 103), comprising: at least a roller (5; 73; 109) in contact
with said winding spindle in the initial phase of winding the web material around
the spindle; a transverse cutting element (19; 69; 117) to cut the web material at
the end of winding one roll and form a initial free end to wind a subsequent roll
around a new winding spindle, said initial free end being inserted between said roller
and said winding spindle, characterized in that a least an electrostatic bar (21; 71; 131) is provided to electrostatically charge
the web material and in that said roller (5; 73; 109) in contact with the spindle is made at least partially of
non-electrically conductive material.
2. Machine as claimed in claim 1, characterized in that said roller (5; 73; 109) comprises a cylindrical wall made completely of non-electrically
conductive material.
3. Machine as claimed in claim 1 or 2, characterized in that said roller is a winding roller (5; 109) which remains in contact with the roll (R)
being formed around said spindle substantially for the entire winding cycle of the
roll.
4. Machine as claimed in claim 1, 2 or 3, characterized in that it comprises two winding rollers ((3, 5) forming a winding cradle (7) in which said
winding spindle (13) is inserted and on which said roll is formed, at least one (5)
of said winding rollers being formed at least partially in non-electrically conductive
material.
5. Machine as claimed in claim 4, characterized in that said electrostatic bar (21) and said transverse cutting element (19) are mounted
on an assembly (17) oscillating around the axis of the first (3) of said winding rollers
(3, 5), at least the second (5) of said winding rollers being made at least partially
of non-electrically conductive material.
6. Machine as claimed in claim 4 or 5, characterized in that the web material is fed to the winding cradle (7) passing along a path that crosses
a nip formed of said two winding rollers (3, 5).
7. Machine as claimed in claim 3, characterized in that it comprises a support (43; 101) for said winding spindle (45; 103), said winding
spindle and said roll being formed around said spindle being maintained in rotation
by said winding roller (51; 109), around which the web material is driven.
8. Machine as claimed in claim 7, characterized by a moving assembly (67) carrying said transverse cutting element (69) and said electrostatic
bar (71), said assembly oscillating around an axis parallel to the axis of rotation
of said winding roller (51) to cut the web material and fasten the web material around
said winding spindle.
9. Machine as claimed in claim 7, characterized by a moving assembly (115) carrying said transverse cutting element (117) and said electrostatic
bar (131), said assembly performing a complete rotation around an axis parallel to
the axis of rotation of said winding roller (109) to cut the web material and fasten
the web material around said winding spindle.
10. Machine as claimed in claim 8 or 9, characterized in that said moving assembly (67; 115) carries a pair of guiding rollers (80, 81; 125, 127).
11. Machine as claimed in claim 10, characterized in that said transverse cutting element (117) is positioned between said guiding rollers
(125, 127) carried by said moving assembly (115).
12. Machine as claimed in claim 1 or 2, characterized in that it comprises a support (43) for said winding spindle (45), a winding roller (51)
in contact with said roll to maintain the roll in rotation while it is being formed,
a moving assembly (67) carrying said electrostatic bar (71), said cutting element
(69) and said roller (73) formed at least partially in non-electrically conductive
material.
13. Machine as claimed in claim 12, characterized in that said roller (73) formed at least partially in non-electrically conductive material
is provided with a movement in relation to the moving assembly which draws it towards
and moves it away from the winding spindle.
14. Machine as claimed in claim 13, characterized in that said moving assembly (67) carries a first actuator (79) to operate said transverse
cutting element (69) and a second actuator (77) to draw said roller (73) towards and
move it away from the winding spindle.
15. Machine as claimed in one or more of the previous claims, characterized in that said roller formed at least partially in non-electrically conductive material has
a cylindrical surface constituted by a reinforced synthetic material.
16. Method to produce rolls of web material wound around winding spindles, comprising
the phases of:
• winding a first roll of web material around a first winding spindle;
• bringing a second winding spindle in contact with the web material;
• cutting the web material, in proximity to said second winding spindle to form an
initial free end and a final free end of web material;
• winding the initial free end of the web material around said second spindle and
starting to wind a second roll, said web material being retained, in proximity to
said initial free end, between said second winding spindle and said roller;
characterized in that said roller is made in non-electrically conductive material.
17. Method as claimed in claim 16, characterized in that said roller in non-electrically conductive material is a winding roller, said rolls
being wound with a peripheral winding system.
18. Method as claimed in claim 16 or 17, characterized by cutting the web material before inserting the free end between said second spindle
and said roller in non-electrically conductive material.
19. Method as claimed in claim 16 or 17, characterized by engaging the web material between said second winding spindle and said roller before
cutting the web material.