Cigarette packing machines

A cigarette packing machine of the type where a hollow packet or wrapper presenting an open head side and a closed bottom side is formed around a tubular mandrel or arbor, and a pushing plunger is provided for ejecting a group of cigarettes previously inserted at the interior of said arbor in the direction of the closed bottom side of the wrapper, further comprises a slip-off device for slipping the hollow wrapper off the arbor concurrently with the displacement of the cigarette group promoted by the pushing plunger. The slip-off device consists of a rotating friction roller arranged towards and away from said arbor, so as to cause the engagement of its peripheral friction surface with the wrapper formed on the arbor.

STATEMENT OF PRIOR ART 
The applicant cites the following prior art, as the closest prior art of 
which he is aware: 
British Specification No. 1,150,159 (FIGS. 1 to 8, and particularly 7 and 
8). 
British Specification No. 1,157,594 (Page 2, lines 95-100). 
British Specification No. 1,292,824 (FIGS. 1 and 2, reference numeral 11 
(puller), page 3, lines 88-105). 
British Specification No. 1,166,236 (the whole document as of interest). 
BACKGROUND OF THE INVENTION 
The present invention relates to improvements in cigarette packing 
machines. More particularly, the invention relates to cigarette packing 
machines of the type in which an orderly group of cigarettes is enclosed 
in a so-called soft pack which consists of a foil wrapped around the 
cigarettes and of an outer paper wrapper. 
In the above mentioned cigarette packing machines, a cigarette group is 
introduced into an open-ended tubular mandrel, called an arbor, around 
which the foil and paper wrapper is formed, said wrapper presenting one 
closed side, which corresponds to the bottom of the cigarette packet. 
Then, the cigarette group is pushed by a pushing plunger, which causes the 
said cigarette group to move through the arbor, against the bottom of the 
wrapper; subsequently, upon prosecution of the movement of the pushing 
plunger, the cigarette group, together with the wrapper vested thereonto, 
are slipped off the arbor and transferred to a receiving station at which 
suitable folders effect to the folding of the flaps at the open side of 
the packet, thus closing the said packet which is ready for the subsequent 
cellowrapping operation. 
The sliding out of the wrapper, or slipping-off, from the arbor, promoted 
by the pushing action of the cigarette group which in its turn is pushed 
by the plunger, presents however an inconvenience which is due to the fact 
that the corners of the wrapper bottom cannot be practically squared out 
in a perfect manner, but have always a certain degree of roundness, so 
that, at high production rates of the cigarette packing machine, the 
cigarette group is pushed against the bottom of the wrapper at a high 
speed and the cigarettes located at the periphery of the bottom, 
particularly in the corner zones, are subjected to a brusque impact with 
the corresponding wrapper portions, and consequently are deformed and/or 
damaged. 
SUMMARY OF THE INVENTION 
The present invention has for its purpose to avoid this inconvenience, 
which mostly depends from the working rate of the pushing plunger, and it 
provides for the association to a cigarette packing machine of the above 
mentioned type, of a device for slipping off at least partially the 
wrapper from the tubular mandrel or arbor, in advance with respect to the 
movement of the cigarette group inside the said arbor promoted by the said 
pushing plunger, in such a manner that the head of the cigarette group 
does not exert any impact or pushing action against the inner side of the 
bottom of the wrapper, at least during the initial phase of the stroke of 
the pushing plunger, when the said plunger is subjected to the maximum 
acceleration and as a consequence there exist the most critical impact 
conditions of the cigarette block against the wrapper. 
The above and other features of the invention, and the advantages deriving 
therefrom, will appear evident from the following detailed description of 
some preferred embodiments of same, made with reference to the attached 
sheets of drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
In FIGS. 1 to 5 there is shown a first embodiment in which the slip-off 
device consists of a friction roller 1, operatively arranged in proximity 
of the tubular mandrel or arbor 2 of a cigarette packing machine, in the 
position of alignment of said arbor 2 with the receiving channel 3 of the 
folding station of the cigarette packing machine. On the said tubular 
mandrel or arbor 2 there has been previously formed the hollow packet or 
wrapper I, presenting an open side. Usually, a plurality of arbors 2 is 
provided on a rotary drum 5 (see FIG. 5) which intermittently rotates so 
as to bring the arbors 2 and the wrappers I formed thereon, sequentially 
in alignment with the said receiving channel 3 of the folding station of 
the packing machine, at which folding station the flaps of the open side 
of the wrapper (now filled with cigarettes) are folded and the cigarette 
packet is closed. Inside each tubular mandrel or arbor 2 there has been 
previously inserted, in a known manner, a group S of cigarettes. Whenever 
an arbor 2 comes to be in alignment with a receiving channel 3, a pushing 
plunger 4 is actuated so as to push the cigarette group S from the arbor 2 
inside the receiving channel 3, while the friction roller 1 enters into 
action and slips the wrapper I off the arbor 2 into the said receiving 
channel 3, concurrently with the displacement of the cigarette group S. In 
this manner, both the cigarette group S and the wrapper I are slipped off 
simultaneously from the arbor 2 into the receiving channel 3, but this is 
done in an independent manner, whereby the advancing head of the cigarette 
group S is not brought into contact with the bottom of wrapper 1. 
The friction roller 1 is supported in such a manner as to assume 
alternatively two positions. In the first position (FIGS. 1 and 4) the 
friction roller 1 is spaced with respect to arbor 2, while in the second 
position (FIGS. 2 and 3) the friction roller 1 engages by pressure the 
wrapper I formed on the arbor 2. It is to be noted that the friction 
roller 1 usually has its peripheral surface lined with rubber or other 
material presenting a high friction coefficient. 
In the first position of the friction roller 1 the drum 5 can 
intermittently rotate so as to sequentially bring the arbors 2 in 
alignment with the receiving channel 3. In the second position, or 
engaging position, the slipping of the wrapper I from the arbor 2 is 
obtained as a result of the friction existing between the friction roller 
peripheral surface and the said wrapper I. When the roller 1 has almost 
completely slipped the wrapper I off the arbor 2, the remaining stroke 
which is necessary to bring the bottom of the wrapper I against the bottom 
abutment member 103 of channel 3 takes place due to the pushing effect of 
the head of the cigarette group S against the inner side of the bottom of 
the wrapper. This final push is practically permissible for the following 
two reasons: firstly, when the head of the cigarette group S starts 
touching and pushing the inside of the wrapper bottom, the resistance 
offered by the wrapper to its sliding out off the arbor 2 is practically 
negligible; secondly, the pushing plunger 4 is in its deceleration phase, 
whereby also the impact of the advancing head of the cigarette group 
against the bottom of the wrapper is practically negligible. 
The phases of the above slipping-off operation are clearly illustrated 
sequentially in FIGS. 1 to 4. 
It is to be noted that, for a perfect operation of the described device, 
the peripheral speed of the friction roller 1 should be equal to the speed 
of pushing plunger 4, and in any case it must be such as to avoid the 
contact of the head of the cigarette group S against the bottom of wrapper 
I, as long as the said wrapper I is subjected to the action of the 
friction roller. 
FIG. 5 shows, by ways of example, a mechanism for the actuation of the 
friction roller 1. The said friction roller 1 is driven into rotation by a 
shaft 12, through a pair of bevel gears. Shaft 12 is inserted in a pair of 
sleeves 13, coaxially aligned on the opposite sides of a stirrup 14 to 
which they are secured. This stirrup is articulated to a fixed support 15 
and presents an arm 16, having at its end a roller 17. This roller 17, due 
to the pulling effect of a spring 18 acting on stirrup 14, is maintained 
in contact with the profile of cam 19. This cam is driven into rotation at 
suitable speed so as to cause, in perfect timing, through the oscillation 
of arm 16 and consequently of stirrup 14, the movement of the roller 1 
towards and away from arbor 2. 
MODIFICATIONS 
FIG. 6 illustrates schematically a second embodiment which uses a rotating 
rubber sector 6, which operates in synchronism with plunger 4 and 
accomplishes a complete revolution at every complete stroke (advance and 
return) of the plunger. 
A third embodiment, illustrated in FIG. 7, employs a rubber finger 7. This 
element is carried at one end of a lever which is pivotally mounted on a 
support 8, integral with slide 104 of plunger 4. The other end 107 of the 
lever carrying finger 7 presents a roller 9, cooperating with a fixed cam 
10. During the forward stroke of plunger 4, finger 7, which is initially 
in lifted position, goes down, thus coming into contact with the wrapper I 
on arbor 2. Then, it moves forward, slipping the wrapper off the arbor, 
until it gets near the arbor outlet. At this point, finger 7 is lifted to 
the inactive position, to allow the next arbor to come in alignment with 
the wrapper closing station 3. Then, as the plunger 4 moves back, the 
finger moves down, slides back on the arbor, and is finally lifted. 
A fourth embodiment is illustrated in FIG. 8 and shows the use of a suction 
head 11, which is provided with a reciprocating rectilinear motion, to 
slip the wrapper I off the arbor 2. In this embodiment, suction head 11 
completes the introduction of the wrapper in the receiving channel 3. In 
this embodiment, there is, obviously, no abutment member 103, this 
function being accomplished by the suction head 11 when it reaches the end 
of its stroke. 
Finally, FIG. 9 illustrates a further embodiment which is formed by the 
combination of a rubber roller 1 with a suction head 11. Obviously, it 
would also be possible to combine a rotary sector 6 with a suction head 
11, as well as to combine a rubber finger 7 with the suction head.