Ventilated cigarettes

Ventilated cigarettes are made by perforating the wrapper of each filter over an area which lies within pre-formed perforations in the uniting band joining the filter to the tobacco rod. The filter wrappers may be perforated by pins on a rolling plate and fluted drum between which filter portions cut from longer filter rods are rolled to stagger the portions so that they can then be pushed into a single row.

This invention is concerned with the manufacture of ventilated cigarettes; 
that is to say, filter-tipped cigarettes which allow air from the 
atmosphere to be drawn in through the side of the filter to mix with smoke 
taken in by the smoker. 
One way of making ventilated cigarettes is described in British patent 
specification No. 1,250,832. According to that specification, completed 
filter cigarettes are perforated by being rolled with the aid of a rolling 
member having pins which form perforations in the filter portion of the 
cigarette. For that purpose, the pins must penetrate the uniting band 
which joins the tobacco portion to the filter, and also the wrapping 
material around the filter portion itself. 
According to the present invention, in the maufacture of ventilated 
cigarettes, filter portions are joined to wrapped tobacco portions by 
pre-perforated web portions which are wrapped around the filter portions 
and overlap and are secured to ends of the tobacco portions, the wrapper 
of each tobacco portion, before it is surrounded by the associated uniting 
band, being perforated over an area which lies within the perforations in 
the uniting band when the cigarette is complete. 
The filter wrappers are preferably mechanically perforated. This can be 
achieved by rolling the filters with the aid of a rolling member carrying 
pins to perforate the wrapper. One advantage of such an arrangement over 
the aforementioned British system described in the patent specification is 
that the pins do not need to penetrate the uniting band (which is commonly 
of a more abrasive material) and therefore have a longer life; 
furthermore, the tendency for the pin-perforated holes to be somewhat 
unattractive (which is a disadvantage in the system according to the above 
British patent specification) is of no account in the present invention 
since those holes are covered by the uniting band; the uneveness of the 
filter wrapper which results from the indentations formed by the pins may 
even by an advantage of the present invention in regard to maximizing the 
ventilation air flow. 
The perforations in the uniting band may be formed by sparking (or by means 
of a laser) in large quantities and with a small diameter so as to be 
substantially invisible. This sparking or laser perforation may be carried 
out during the manufacture of the reels of uniting band material, or on 
the filter attachment machine. 
In one preferred arrangement, filter rods of double unit length cut from a 
longer rod are perforated by means of a number of sets of pins (e.g. six, 
as described with reference to the drawings) before being formed into a 
single row; with such an arrangement the life of the pins is increased 
(e.g. sixfold) because the work of preforating the filter wrappers is 
shared by all the sets of pins.

FIG. 1 shows a ventilated filter cigarette comprising a tobacco portion 10 
and a filter portion 12. The filter portion is joined to the tobacco 
portion by a uniting band 14 which surrounds the entire filter portion and 
overlaps and is secured to the adjacent end of the tobacco portion. The 
uniting band has, along a region lying approximately midway between the 
ends of the filter portion, an area 14A which is perforated, for example 
by sparking, to allow ventilation air to flow into the filter. Within the 
perforated area 14A of the uniting band, the wrapper of the filter portion 
has a number of circumferentially extending rows of indentations forming 
perforations 16; only three rows are shown, but there may in practice be 
more. 
Instead of the perforated area of the uniting band having numerous very 
small holes, it could have one or more rows of discreet, somewhat larger 
holes. 
FIGS. 2 to 6 show one way in which the perforations in the wrappers of the 
filter portions may be formed in a filter attachment machine. 
FIGS. 2 and 3 show part of the general arrangement of the machine, which is 
similar to the Molins PA 8 filter attachment machine. The machine includes 
a hopper A which is arranged to receive filter rods R which are of 
multiple-unit length. Each rod, in the example shown, is six times the 
length of the filter portion which forms part of each completed filter 
cigarette. 
The rods R are fed from the hopper A by a fluted drum B and are then 
received by a fluted drum C. Disc knives K1 and K2 adjacent to the drum C 
cut each rod R into three equal portions R1, R2 and R3 each of which 
comprises a double-length filter portion. Each group consisting of 
portions R1, R2, R3 remains axially aligned while being tranferred from 
the drum C to a fluted drum D. The filter portions R1, R2 and R3 are then 
received by a drum E which is in three parts arranged to receive the 
respective filter portions in staggered formation, as shown in FIG. 3; 
this will be further described with reference to FIG. 4, which is an 
enlargement mainly of the drum E. 
The staggered filter portions are then received by a drum F and are pushed 
into a single row by converging fixed walls W1 and W2 extending around 
part of the drum F. Thus a single row of double-length filter portions is 
delivered to a fluted drum G which also receives, in each of its flutes, 
two tobacco-filled rods T1 and T2 adjacent to opposite ends of each double 
filter portion. The tobacco rods are delivered to the drum G by a drum H 
(FIG. 2). Each assembly consisting of a pair of tobacco portions T1 and T2 
with an interposed double-length filter portion is received from the drum 
G by a fluted drum L which delivers the assemblies to a rolling drum by 
which adhesive-coated uniting bands are wrapped around the filter portions 
and around adjacent ends of the tobacco portions. The resulting double 
cigarettes are finally cut through the middle to form individual filter 
cigarettes. 
In order not to close the perforations in the uniting bands, adhesive is 
preferably not applied to the uniting bands in the area of the 
perforations, except at the edges of the bands. 
A description of a possible arrangement of the rolling drum is contained in 
our British Patent Application No. 40449/74 (and corresponding German 
Offenlegungsschrift No. 25 40 154), in which the fluted drum 2 corresponds 
to drum L in the present specification. 
The arrangement whereby the filter portions R1, R2 and R3 are staggered on 
the drum E is basically as described in our U.S. Pat. No. 3,405,579, to 
which reference is directed in its entirety. 
The drum E comprises three axially spaced parts E1, E2 and E3 which receive 
respectively the filter portions R1, R2 and R3. FIG. 4 shows in elevation 
the drum E and associated parts. Filter groups R (already cut) are 
delivered to the drum E by the drum D, being stripped from the drum D by 
three fingers 20E extending from three sections 20' of a rolling plate 20. 
The three parts 20' of the rolling plate cooperate respectively with parts 
E1, E2 and E3 of drum E and are carried by a bracket 23. The drum D has 
deep circumferential grooves into which the fingers 20E extend to strip 
the filter rods from the drum D in a known manner. 
After transfer to the drum E, the rod sections R1, R2 and R3 are staggered 
and perforated in the manner described below. 
The three sections E1, E2 and E3 of the drum E are all identical. Each has 
four flutes 28 at 90.degree. intervals, as shown in FIG. 5. However, the 
flutes of the three drum sections are evenly staggered; consequently in 
FIG. 4 the flutes of all three drum sections are shown, in dotted outline, 
at 30.degree. intervals. This enables the three portions of each filter 
rod to be rolled backwards into staggered positions as already mentioned. 
Each rolling plate section 20' has, on each side of it, an arcuate member 
20D which carries three rows of pins 24 and is secured in position by 
screws 20A. Also, as shown in FIG. 6, but not in FIGS. 4 and 5, each 
section E1, E2 and E3 of the drum preferably has a replaceable annular 
member 71 at each end carrying two rows of pins 73 interrupted by recesses 
74 forming extensions of the flutes 28 in the drum. The positions of the 
pins are such that the pins 73 form rows of holes lying between the rows 
of holes formed by the pins 24. 
Each filter portion is rolled through at least 2 revolutions while being 
perforated by the pins. While this rolling is taking place, the filter 
portions are prevented from dropping into the flutes 28 by fixed curved 
fingers 30. These fingers are carried by a guide 100 associated with the 
drum D and extend into circumferential grooves 29 in the drum sections E1, 
E2 and E3 (see for example FIG. 6); the outer surface of each finger is 
slightly below the outer surface of the drum so as not to interfere with 
the filters when rolling on the drums. 
FIG. 4 shows one group of filter portions RA at the transfer point between 
the drums D and E. The preceding group RB has just started to be 
perforated. Group RC is about half way through the perforation operation. 
Group RD has passed the pins (i.e. perforation has been completed and has 
also passed the end 30A; consequently portion RD1 of that group is 
beginning to drop into the adjacent flute of drum E1. Portions RE1 and RE2 
of the preceding group have already dropped into flutes in drums E1 and 
E2, while portion RE3 is about to be caught up by flute 28' of drum E3. 
The trailing portion RF3 of the preceding group is being transferred to 
the drum F, the portions RF1 and RF2 of the group already having been 
transferred to drum F. 
After entering a flute 28, each filter portion is held in the flute by 
suction supplied via a passage 28A, and via a slot 120 in a sleeve valve 
121, from a suction space 123. 
Filter rolling surfaces 10 and 26A respectively on the drum and rolling 
plate (see FIG. 6) may be coated with a rough material to provide a good 
grip. 
It should be noted that each rod portion, while being rolled, is slightly 
compressed between the drum and the rolling plate 20. The pins 24 may, for 
example, project radially inwards from the inner rolling face of the plate 
20 by between 0.025 and 0.030 inches, and may be arranged to form holes of 
about 0.008 inch diameter; the same may apply to the pins 73. Preferably, 
however the pins are inclined to the corresponding radius by about 
20.degree. so as to enter the wrapper approximately at right angles. 
It should also be understood that the drum E rotates with a peripheral 
velocity which is considerably greater than that of the drum D, since the 
axes of the rods, during rolling, move at one half the peripheral velocity 
of the drum E. The speed of rotation of drum E is in fact five times that 
of drum D. The peripheral velocity of the drum F is approximately equal to 
that of the drum E. 
The rolling plate 20 may be releasably mounted so that it can move away 
from the drum E, against the action of a holding spring, if a jam (i.e., a 
build-up of filter portions) occurs between the rolling plate and the 
drum. 
We have found that it is desirable to form numerous holes in a fairly 
narrow band extending around each filter wrapper. For example, by 
perforating each filter while rolling it through a number of revolutions, 
it is possible to form approximately 300 or more perforations; the total 
number may be as high as 600. This is facilitated by the provision of pins 
on the drums E1, E2 and E3, as well as on the rolling fingers 20. 
If the pins are set very close together then there is a danger that the 
pressure of each pin point on the filter wrapper is insufficient to 
penetrate the wrapper. For that purpose, the point of each pin needs to be 
sharp. The shape of the point may be conical; alternatively, each point 
may be formed by grinding the pin to form four converging facets; the 
facets may come to a sharp point or may define an edge with sharp points 
at both ends. 
The pins on the rolling fingers and/or on the drum sections may be at 
varying heights. For example, the tips of the pins may be at distances 
from the drum or rolling plate surface ranging between 1 and 2 mm. 
In place of the perforating pins 24, rotating disc knives may be used to 
cut slits in the filter wrappers while they roll past the knives. For 
example, each knife may project radially inwards beyond the rolling 
surface of the associated rolling plate by a distance of about 0.75 to 1 
mm. Each plate section may have, on each side, a number of such knives 
spaced around the axis of the drum E to produce a number of 
circumferentially spaced slits in the wrapper of each filter portion. For 
example, there may be three parallel driven spindles which pass through 
the rolling plate at circumferentially spaced positions and carry stacks 
of knives adjacent to opposite sides of each plate section; the spindles 
would be so positioned that each filter portion is slit partially around 
its circumference at three circumferentially spaced positions, i.e. 
receives three sets of multiple slits; each stack of knives may be 
machined from a single piece of metal. 
Provision may be made for sharpening the knives continuously or from time 
to time. Alternatively, the knives may be made of a highly wear-resistant 
material (e.g. tungsten carbide), the knives being simply replaced when 
necessary. 
Instead of cutting slits in the wrapper of the filter, each knife may have 
a serrated edge which mills away part of the wrapper. FIG. 7 shows an 
example of such an arrangement. 
FIG. 7 shows one drum section E1 (as in the previous example). While being 
rolled on the surface of the drum E1 by means of the rolling plate 20, 
each filter portion is formed with a circumferentially extending row of 
milled grooves by means of a milling device 60, each groove being parallel 
to the axis of the filter. The device 60 comprises a number of axially 
spaced milling discs 60A mounted on a shaft 60B of which the axis lies in 
a plane normal to the axis of the drum E1. The disc diameters vary so that 
each disc projects slightly into the gap between the drum E1 and the 
rolling surface of the plate 20. Each disc 60A may have a serrated or 
other suitable edge for milling a shallow groove in the surface of the 
filter rod as it passes by. 
In addition the drum E1 may have groups of pins 62 to provide additional 
perforations. The pins are inclined as described with reference to the 
previous example. 
It will be understood that similar milling devices 60 are provided wherever 
necessary to form perforations in the filter portions. 
Another possibility is as follows. Each of the spindles carrying the knives 
K1 and K2 may also carry axially spaced sets of smaller-diameter knives or 
milling tools for cutting slits or for milling grooves part way into the 
filter. Slitting or milling of the filters may alternatively be carried 
out at any other stage during their conveyance between the filter rod 
forming device and the filter assembly station. This applies especially 
while the filters are being conveyed by fluted drums; for example, 
circumferential slits may be formed on one side while the filters are on 
one drum, and on the other side while on another drum. Alternatively, 
longitudinal slits or grooves may be formed while the filter rod (either 
while still continuous or after cutting) is moving longitudinally. 
Another possibility is that the filter rods, e.g. while moving slowly on 
the drum B, may pass a stack of serrated discs mounted on a shaft which is 
driven so that the edges of the serrations penetrate the filter wrapper 
and drive the filter about its axis so as to form perforations 
substantially all the way around the wrapper; in other words, the filters 
are made to spin in the flutes of the drum, which flutes for this purpose 
would be highly polished. Alternatively, a rolling plate with pins may be 
provided to spin the filter rods in their flutes while perforating them. 
The flutes may have ports through which suction is applied for holding the 
filters in the flutes while the filters are not being spun, and pressure 
air may be supplied to those ports during spinning to produce an 
elementary air bearing. During spinning, the filters may be held slightly 
away from the bottoms of the flutes by arcuate stationary fingers 
extending into circumferentially extending grooves in the drum, so that 
the filters rub substantially only on the fingers, which may have 
low-friction coatings on their outer surfaces. For example, the arcuate 
fingers may extend obliquely downwardly between the drums B and C (FIG. 2) 
and may first lift the filters slightly from the drum B (for the purpose 
of spinning) and then help to strip the filters from the drum B so that 
they then enter the flutes in the drum C. 
FIG. 8 of the accompanying drawings shows another possible way of 
perforating the filters. A filter hopper 50 (corresponding to hopper A in 
FIG. 2) delivers filter rods to a fluted drum 52 (corresponding to drum B 
of FIG. 2). Instead of entering directly into the flutes of the drum 52, 
the filter rods pass between a rolling drum 54 and a rolling plate 56 both 
of which have sets of pins 54A and 56A respectively for forming bands of 
perforations at appropriate axially spaced positions around each filter 
rod. Alternatively, the pins 54A or 56A may be omitted. It will be seen 
that each filter rod 58 is rolled through several revolutions while being 
perforated. To ensure an unbroken succession of filter rods in the rolling 
space between the drum 54 and plate 58, conveyor bands 59 are provided; 
these form the floor of the hopper and support opposite ends of the 
filters so as to move the filters towards the drum 54. The peripheral 
speed of the drum 54 is greater than the speed of the bands 59, so that 
the filter rods are spaced apart as they travel round the drum. 
Instead of entering directly into the flutes of the drum 52, the filters 
may, on leaving the drum 54, pass into another hopper space (equivalent to 
hopper A in FIG. 2) from which they are delivered by a fluted drum 
corresponding to drum B in FIG. 2. 
Another possible way of perforating the filter rods is as follows. The 
filter rods may be fed into the filter hopper in the manner of any one of 
the examples described in U.S. Pat. No. Re. 28,383 (of W. Rudszinat); 
however instead of the filters being driven into the filter hopper by 
being gripped on both sides by bands, they may be driven forward by means 
of bands on one side in cooperation with a stationary plate on the other 
side, so that the bands convey the filters with a rolling action; and the 
plate may be formed with pins or other means for perforating the filters 
while they are rolling. 
FIG. 9 shows a modification of the last-mentioned arrangement. It includes 
a filter rod hopper 170 and drum 181 (corresponding basically to the 
hopper A and drum B in FIG. 2). The rods are fed into the hopper by a 
device comprising bands or sets of bands 171, 172 which deliver the rods 
(without rolling) into a gap between a drum 173 and a fixed plate 174. The 
drum 173 and plate 174 both have sets of pins whereby the rods are 
perforated while being rolled between the drum and the plate; 
alternatively, the pins on either the drum or the plate may be omitted. A 
cover plate 175 over the drum 173 holds the rods out of contact with the 
drum 173 once they are in the hopper. 
Another way of perforating the filter rods is as follows. On being 
transferred from one fluted drum to another (e.g., from drum B to drum C, 
or from drum E to drum F in FIG. 2) the filter rods or portions may 
initially be held out of the flutes of the receiving drum by means of one 
or more fingers like the fingers 30 shown in FIGS. 4 and 5. While that is 
happening, the rods are rolled by a pin-carrying rolling plate to form 
perforations, where necessary, in basically the manner described above 
with reference to FIGS. 4 and 5. As before, the surface of the receiving 
drum may also have outwardly-projecting pins to form additional 
perforations. Also, as before, the filter rods will drop into the flutes 
of the receiving drums after passing the downstream end of the finger or 
fingers. 
This method of perforation may also, in principle, be applied to finished 
cigarettes or to the double cigarettes before they are cut through the 
middle to form individual filter cigarettes. The means for perforating the 
rods while they are rolling may take various forms; it may be a 
non-mechanical device, e.g. a laser.