[0001] The present invention relates to a curling device preferably for cigarette making
machines.
[0002] The invention finds application to advantage in the art field of cigarette making
machinery, and in particular of filter tip attachments, that is to say machine units
by which filters and cigarettes are assembled. Reference is made explicitly to this
art field in the following specification, albeit with no limitation in general scope
implied.
[0003] Conventionally, cigarettes and filter tips are assembled by interposing a double
length filter plug between two axially aligned cigarette sticks, then joining the
filter to the sticks on each side by applying a previously gummed tipping paper, and
ultimately cutting the double assembly in half to create two single filter-and-cigarette
assemblies.
[0004] A filter tip attachment generally comprises a feed station from which a continuous
strip of paper material is advanced at a predetermined velocity and under a predetermined
degree of tension along a feed path, likewise predetermined; the feed path passes
both through a gumming station at which an adhesive substance is applied to one surface
of the strip destined to engage the filter-and-cigarette assembly, and through a cutting
unit by which the continuous strip is divided into discrete tipping papers ready for
application.
[0005] Each tipping paper separated by the cutting unit is positioned at an intermediate
transfer station and there associated initially with a respective filter-and-cigarette
assembly, before being affixed permanently to the selfsame assembly at a further station.
The step of affixing the tipping paper permanently to the filter-and-cigarette assembly
is accomplished normally by wrapping the paper around the assembly.
[0006] This wrapping operation is much facilitated by a curling device installed between
the feed station and the cutting unit, which engages the advancing strip and brings
about a plastic deformation of the internal fibres. The material thus assumes a given
curvature, when relieved of longitudinal tension, with the result that the application
of the papers to the respective filter-and-cigarette assemblies is made easier.
[0007] Notwithstanding the application of tipping papers to filter-and-cigarette assemblies
is assisted thus by the use of conventional curling devices, which consist essentially
in a sharp-edged or blade-like element offered in contact to the continuous strip
and designed to weaken the material transversely, it has been found that such devices
betray certain drawbacks attributable principally to the friction generated at the
area of contact between the device and the strip.
[0008] In particular, it has been observed that the deforming action of the curling device
generates high frictional forces tending often to degrade or to break the strip material
at the high operating speeds of filter tip attachments now in service.
[0009] The object of the present invention is to address and overcome the problems encountered
in prior art solutions by setting forth a curling device for cigarette makers capable
of deforming the fibres of a continuous strip in such a way as to facilitate the operation
by which tipping papers are wrapped around filter-and-cigarette assemblies, while
at the same time guaranteeing the integrity of the continuous strip and the quality
of the finished cigarettes even at high operating tempos.
[0010] The stated object is realized according to the invention in a device for curling
a continuous strip of paper material caused to advance along a predetermined feed
path toward at least one cutting unit by which the selfsame strip is divided into
discrete lengths. Such a device presents at least one curling element operating on
one surface of the advancing strip at a contact zone in such a manner as to deform
the strip relative to its longitudinal dimension, and is characterized in that it
includes vibrator means associated with the curling element.
[0011] The invention will now be described in detail, by way of example, with the aid of
the accompanying drawing, which is a schematic illustration showing one portion of
a cigarette maker equipped with a curling device according to the present invention.
[0012] Referring to the drawing, 1 denotes a curling device, in its entirety, embodied in
accordance with the present invention.
[0013] The curling device 1 is associated with a given portion 2 of a cigarette maker, and
in particular with a filter tip attachment comprising at least one feed station A
from which a continuous strip 3 of paper or similar material is advanced steadily
toward successive stations of the machine.
[0014] The continuous strip 3 is decoiled from a roll 4, subject to a predetermined tension
and at a given velocity, and advanced along a predetermined feed path P that passes
in succession through a gumming station 5, where one or more adhesive substances are
applied to at least one adhesion surface 3a of the continuous strip 3, and a cutting
unit 6 by which the gummed strip 3 is divided into discrete lengths, or tipping papers
7, each serving to join at least one filter permanently to a respective cigarette
stick.
[0015] The adhesive substances in question are applied at the gumming station 5 by means
of at least one gumming device 8 comprising an applicator roller 9 that acts directly
on the adhesion surface 3a of the continuous strip 3, and a reaction roller 10 acting
on the surface of the strip opposite from the applicator roller 9.
[0016] As discernible from the accompanying drawing, the strip 3 passes over a guide roller
11 positioned upstream of the curling device 1, then through a pair of pinch rolls
12 downstream of the selfsame device 1.
[0017] The cutting unit 6 generates the aforementioned tipping papers 7 utilizing a suction
roller 14 and an auxiliary roller 15 of which the respective axes of rotation 14a
and 15a are disposed substantially horizontal and parallel one with another.
[0018] The continuous strip 3 is taken up by the suction roller 14, and directed through
a cutting zone 16 at which the selfsame roller 14 interacts with the auxiliary roller
15 in such a way as to divide the strip 3 into single tipping papers 7.
[0019] The suction roller 14, which presents a diameter greater than that of the auxiliary
roller 15 and rotates at a peripheral velocity higher than the linear velocity of
the advancing strip 3, carries a plurality of angularly equispaced blades 17 with
substantially straight cutting edges set skew to the axis of rotation 14a.
[0020] The auxiliary roller 15 rotates at a peripheral velocity substantially matching the
linear velocity of the advancing strip 3, and carries a plurality of substantially
radial blades 18 equispaced around its surface of revolution. These blades 18 present
cutting edges set substantially parallel to the axis of rotation 15a of the roller
15.
[0021] The cutting unit 6 is followed along the feed path P by a conveying roller 19 of
conventional embodiment, rotatable anticlockwise, as viewed in the drawing, about
an axis 19a extending parallel to the axes 14a and 15a of the cutting rollers. The
conveying roller 19 affords a plurality of fluted recesses 19b extending parallel
to the straight line generators of the revolving surface, in which relative filter-and-cigarette
assemblies 20, each consisting in two cigarette sticks separated by a double length
filter plug, are retained by suction in conventional manner. The filter-and-cigarette
assemblies 20 are caused to advance broadside by the conveying roller 19 through a
transfer zone 21 where each successive tipping paper 7 generated by the cutting unit
6 is offered to the surface of a respective assembly 20.
[0022] As discernible from the accompanying drawing, the curling device 1 is located upstream
of the cutting unit 6, considered relative to the feed direction D followed by the
continuous strip 3. In a preferred embodiment, the device 1 will be positioned between
the feed station A and the cutting unit 6, and more exactly between the feed station
A and the gumming station 5.
[0023] In particular, and as intimated previously, the device 1 comprises a curling element
13, embodied as a bar 22 appearing substantially triangular in section, of which one
edge 13a is offered to the adhesion surface 3a of the continuous strip 3 at a contact
zone denoted 23.
[0024] The aforementioned guide rollers 11 and pinch rolls 12 are positioned along on the
feed path P, relative to the curling element 13, in such a way as to establish a leg
presenting a Vee profile of which the vertex coincides with the edge 13a of the bar
22. With the strip 3 thus constrained to make a sharp change in direction at the contact
zone 23, the structure of the material becomes permanently deformed, assuming a predetermined
curvature such that the gummed surface 7a of each tipping paper 7 separated by the
cutting unit 6 and then offered in contact to a filter-and-cigarette assembly 20 will
be concavely profiled. In other words, the edge 13a of the curling element 13 is applied
forcibly to the continuous strip 3 as it passes through the contact zone 23, compressing
the internal fibres beneath the surface directed toward the curling element 13, while
stretching the internal fibres beneath the surface directed away from the selfsame
curling element.
[0025] The curling element 13 is connected by a rod 24 to vibrator means indicated schematically
as a block denoted 25, such as will cause the bar 22 to vibrate at a predetermined
frequency. Naturally enough, the rod 24 might be replaced by any other means of connection
capable of transferring the energy from the vibrator means 25 to the bar 22, or alternatively,
the bar 22 could be coupled direct to the vibrator means 25.
[0026] The vibrator means 25 are of conventional type, for example electrical, mechanical
or pneumatic in operation, and preferably will take the form of an ultrasound generator.
[0027] The vibratory motion transmitted to the bar 22 by the vibrator means 25 can be rectilinear,
oriented along an essentially rectilinear direction parallel to the rod 24, hence
transverse to the strip 3, or oriented along a direction transverse to the rod 24
and coinciding with the direction followed by the strip 3 as it passes through the
contact zone 23.
[0028] Finally, the vibratory motion can be generated by two directional components, one
transverse to the other, in which case the trajectory described could be looped, elliptical
or circular in outline.
[0029] It has been observed that the motion transmitted by the vibrator means 25 to the
bar 22 has the effect of reducing frictional forces in play at the contact zone 23
when the edge 13a of the curling element engages the adhesion surface 3a of the strip
3, so that the tension values registering in the strip 3 upstream and downstream of
the curling device 1 can be rendered uniform.
[0030] Finally, with the adoption of a curling device 1 according to the present invention,
the treatment applied to the strip 3 in producing a given depth of curl at a given
rate of feed is more delicate, and any risk of tearing the material is avoided.
1. A device for curling a continuous strip (3) of paper material advancing along a predetermined
feed path (P) toward at least one cutting unit (6) by which the selfsame strip is
divided into discrete lengths (7), wherein the device (1) presents at least one curling
element (13) operating on one surface of the advancing strip (3) at a contact zone
(23) in such a manner as to deform the strip relative to its longitudinal dimension,
characterized
in that it includes vibrator means (25) associated with the curling element (13).
2. A device as in claim 1, wherein the curling element (13) is set in motion by the vibrator
means (25) at a predetermined frequency and in a substantially rectilinear direction,
transverse to the strip (3).
3. A device as in claim 1, wherein the curling element (13) is set in motion by the vibrator
means (25) at a predetermined frequency and in a direction substantially parallel
to the direction followed by the strip (3) through the contact zone (23).
4. A device as in claim 1, wherein the curling element (13) is set in motion by the vibrator
means (25) at a predetermined frequency and in such a way as to describe a trajectory
determined by two directional components transverse one to the other.
5. A device as in claim 1, wherein the curling element (13) is set in motion by the vibrator
means (25) at a predetermined frequency and in such a way as to describe a closed
loop trajectory.
6. A device as in claims 1 to 5, wherein the vibrator means (25) are electrical, mechanical
or pneumatic in operation.
7. A device as in claim 6, wherein the vibrator means (25) consist in an ultrasound vibrator
device.