Method and machine for simultaneously producing a number of cigarette rods

A method and machine whereby at least two strips of paper, after being supplied with respective continuous layers of shredded tobacco, are fed along a forming beam by respective conveyor belts which are deformed transversely to gradually wind the respective strips about the respective layers and so form respective tubular wrappings, each presenting a respective longitudinal lateral appendix, an inner lateral portion of which is gummed by a respective gumming device and then brought into contact with an outer surface of the respective tubular wrapping to form a respective continuous cigarette rod; the inner lateral portions of the appendixes all facing the same way, and being gummed at an intermediate point of the forming beam.

BACKGROUND OF THE INVENTION 
The present invention relates to a method of simultaneously producing a 
number of cigarette rods. 
In cigarette manufacturing machines, and as described in U.S. Pat. No. 
4,336,812, at least two parallel, side by side strips of paper are fed on 
to respective conveyor belts, the transportation branches of which extend 
over a forming bed and through a loading station where a central portion 
of each strip is fed with a respective continuous layer of shredded 
tobacco. Downstream from the loading station, the transportation branches 
of the conveyor belts engage respective variable-section grooves formed 
along a forming beam fitted to the forming bed, and are deformed 
transversely by the grooves to gradually wind the respective strips about 
the respective layers of tobacco to form respective tubular wrappings. 
Each of the wrappings presents a respective longitudinal lateral appendix, 
the inner surface of which is gummed by a respective gumming device and 
then brought into contact with the outer surface of the tubular wrapping 
to form a respective continuous cigarette rod. 
As described in U.S. Pat. No. 4,336,812 referred to above, the inner 
surfaces of said appendixes face opposite ways to simplify as far as 
possible the assembly and maintenance of said gumming devices. Such an 
arrangement, however, seriously complicates any intervention on the 
forming bed on the part of the operator, as well as the assembly of 
removable safety covers on the outward-facing part of the forming bed. 
To overcome this drawback, the gumming devices are therefore known to be 
located upstream from the loading station. Even this solution, however, is 
not without drawbacks, in that, on reaching the loading station, each 
paper strip presents a lateral portion gummed on the side facing the 
respective layer of tobacco, so that any stray particles of tobacco from 
the layer may adhere to the gummed portion of the strip, thus resulting in 
the formation of defective cigarettes. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a method of producing a 
number of continuous cigarette rods, designed to overcome the 
aforementioned drawbacks. 
More specifically, it is an object of the present invention to provide a 
method of producing a number of continuous cigarette rods, while at the 
same time enabling free access by the operator to the rod forming bed. 
Yet a further object of the present invention is to provide a method 
enabling the structure of the gumming devices to be simplified and 
combined as far as possible. 
According to the present invention, there is provided a method of 
simultaneously producing a number of cigarette rods, the method comprising 
the steps of feeding at least two strips of paper, by means of respective 
conveyor belts, along a given path extending in a given traveling 
direction through a loading station, each conveyor belt coming into 
contact with an outer surface of the relative strip; transferring a 
respective continuous layer of tobacco on to an inner surface of each said 
strip at the loading station; feeding the strips and respective layers, by 
means of said conveyor belts, along a forming beam; gradually deforming 
the conveyor belts transversely, by means of the forming beam, to 
gradually wind the respective strips about the respective layers and so 
form respective tubular wrappings presenting respective longitudinal 
lateral appendixes projecting outwards and presenting respective 
longitudinal lateral inner surface portions; gumming, on each strip and by 
means of a respective gumming device, a lateral surface portion 
corresponding to the relative said lateral inner surface portion; and 
turning said appendixes over on to the respective tubular wrappings to 
form respective continuous cigarette rods; characterized in that the 
strips are deformed transversely so as to form respective said appendixes 
with their lateral inner surface portions all facing the same way; said 
lateral inner surface portions being gummed at an intermediate point of 
the forming beam by means of respective gumming devices located on the 
same side of the forming beam. 
The present invention also relates to a machine for simultaneously 
producing a number of cigarette rods. 
According to the present invention, there is provided a machine for 
simultaneously producing a number of cigarette rods, the machine 
comprising a forming beam for forming at least two cigarette rods; and, 
for each said cigarette rod, a conveyor belt which is brought into contact 
with an outer surface of a respective strip of paper, and feeds the strip 
along a given path extending at least partly along said forming beam; a 
loading station located along said path and upstream from the forming beam 
in a traveling direction of the conveyor belts; supply means for 
transferring a respective continuous layer of tobacco on to an inner 
surface of each said strip at the loading station; and a gumming unit 
comprising, for each conveyor belt, a gumming device for gumming a lateral 
surface portion of each strip; the forming beam presenting, for each said 
conveyor belt, a variable-section groove engaged by the conveyor belt and 
for gradually deforming the conveyor belt transversely to gradually wind 
the respective strip about the respective layer of tobacco so as firstly 
to form a respective tubular wrapping presenting a longitudinal lateral 
appendix projecting outwards and presenting a longitudinal lateral portion 
of said inner surface corresponding to said lateral surface portion, and 
so as secondly to turn said appendix over on to the respective tubular 
wrapping; characterized in that said grooves are substantially identical, 
for transversely deforming the respective strips in such a manner that 
said appendixes are arranged with their lateral inner surface portions all 
facing the same way; the gumming devices being located at an intermediate 
point of the forming beam and on the same side of the forming beam.

DETAILED DESCRIPTION OF THE INVENTION 
Number 1 in FIG. 1 indicates a manufacturing machine for simultaneously 
producing at least two cigarette rods 2 (FIG. 2). Machine 1 comprises a 
supporting frame 3 supporting a known device 4 for supplying at least two 
paper strips 5, each slightly wider than the circumference of cigarette 
rods 2; a known device 6 for supplying shredded tobacco 7; and a device 8 
for forming cigarette rods 2, and in turn comprising a forming bed 9 
located at the top of frame 3 and presenting a free lateral surface 10 
(FIG. 2) located at the front in relation to the operator (not shown) 
controlling machine 1, and which hereinafter is referred to as "front 
surface 10." Device 8 also comprises, for each strip 5, a conveyor belt 11 
looped about two pulleys 12 and 13 and powered by a drive cylinder 14 to 
feed respective strip 5 along a given path P extending along bed 9. 
Device 4 feeds each strip 5 on to respective belt 11 in such a manner that 
the outer surface 15 of strip 5 contacts the transportation branch 16 of 
belt 11, which feeds strip 5 in a given traveling direction 17 and through 
a loading station 18 located along path P and where a respective 
substantially uniform layer 20 (FIG. 2) of tobacco 7 is fed by device 6 on 
to the inner surface 19 of strip 5. 
Layers 20 are substantially identical, and adhere to the bottom surface of 
the bottom branch of respective suction conveyor belts 21, 22 forming part 
of device 6 and extending partly over bed 9. Each conveyor belt 21, 22 
slopes downwards and is looped about a bottom pulley 23 at station 18 and 
about a top pulley 24. Device 6 also comprises two known shaving disks 25 
for shaving the bottom surface of layers 20, which are substantially 
narrower than respective strips 5. More specifically, and as shown in FIG. 
2, when deposited on to respective strip 5, each layer 20 leaves two 
lateral portions 26 and 27 of inner surface 19 of strip 5 exposed. 
Device 8 for forming cigarette rods 2 also comprises a forming beam 28 
supported on bed 9 and extending along path P, downstream from station 18 
in direction 17. As shown more clearly in FIGS. 2 and 3, beam 28 comprises 
a bottom plate 29 and, for each belt 11, a top plate 30 supported on the 
top surface 31 of plate 29. More specifically, plate 29 is longer than 
plate 30, and presents a perfectly flat initial portion 32 projecting in 
relation to plate 30, located adjacent to station 18, and contacting the 
bottom surfaces of transportation branches 16 of belts 11. 
Further away from station 18 along path P, plate 29 presents, for each belt 
11, an upper groove 33 extending along path P, beneath respective belt 11, 
and which, in relation to surface 31, gets gradually deeper to assume a 
curved section with a radius of curvature varying in inverse proportion to 
the distance from station 18; which section eventually assumes a constant, 
substantially semicylindrical shape with a radius of curvature 
substantially equal to that of cigarette rods 2. Each plate 30 on the 
other hand presents a respective recess 34 extending along respective 
groove 33, and which, as of station 18, gets gradually narrower until it 
is eventually reduced to a straightforward vertical slit 35 defined by two 
lateral walls 36 and 37. Downstream from station 18 and at an intermediate 
portion 38 of beam 28, wall 36 presents a respective end portion 39 
projecting upwards in relation to wall 37, and in turn presenting an inner 
surface 40 facing frame 3. Grooves 33 are substantially identical, and 
surfaces 40 of walls 36 both face frame 3 on the opposite side to front 
surface 10 of bed 9. 
Transportation branch 16 of each belt 11 extends along respective groove 
33, in contact with which, branch 16 is gradually curved inwards until, 
cooperating with respective recess 34, it eventually assumes a 
substantially cylindrical shape. As a consequence of the transverse 
deformation of branches 16, respective strips 5 are also deformed 
transversely, and are wound about respective tobacco layers 20 to form 
respective tubular wrappings 41, each of which presents a lateral appendix 
42 projecting outwards through respective slit 35, and in turn presenting 
a surface 43 facing away from front surface 10 and forming a longitudinal 
lateral portion of surface 19 corresponding to respective lateral portion 
26. 
Device 8 also comprises a gumming unit 44 supported on frame 3, to the side 
of and at intermediate portion 38 of beam 28, and on the opposite side to 
front surface 10 of beam 28. Gumming unit 44 provides for gumming surfaces 
43 of appendixes 42, which, immediately downstream from unit 44, are 
turned over in known manner on to respective surfaces 15 to which they 
adhere to form respective cigarette rods 2. 
Unit 44 comprises two gumming devices 45 and 46, each associated with a 
respective cigarette rod 2, and each of which provides for depositing an 
adhesive substance (not shown) on to respective surface 43. 
Devices 45 and 46 comprise respective box elements 47 and 48 located 
substantially one over the other and respectively below and above surface 
31; and respective gumming disks 49 and 50 fitted to respective elements 
47 and 48, located facing each other over element 47 and beneath element 
48 respectively, and slightly offset in relation to each other along path 
P. Disks 49 and 50 are identical, are positioned parallel to each other 
over surface 31, and are inclined towards surface 31 and front surface 10 
so as to rotate, e.g. anticlockwise in FIG. 3, about respective axes 51 
and 52 parallel to each other and inclined in relation to surface 31. 
Disks 49 and 50 are defined externally by respective conical lateral 
surfaces 53 and 54 coaxial with respective axes 51 and 52 and tangent to 
respective surfaces 43. 
Unit 44 also comprises two devices 55 and 56 associated respectively with 
gumming devices 45 and 46, and for respectively supplying devices 45 and 
46 with said adhesive substance. More specifically, devices 55 and 56 
comprise respective gumming rollers 57 and 58 presenting respective axes 
59 and 60 crosswise to respective axes 51 and 52, and which are supported 
for rotation about respective axes 59 and 60 by respective tubular 
appendixes 61 and 62, the first extending laterally from element 47 and 
upstream in relation to direction 17, and the second extending from 
element 48 and downstream in relation to direction 17. Rollers 57 and 58 
present respective curved lateral surfaces 66 and 67 coaxial with 
respective axes 59 and 60, and which are supplied with said adhesive 
substance by respective outlet conduits 63 and 64 of a known dispensing 
device 65 common to devices 55 and 56. Surfaces 66 and 67 are positioned 
contacting respective surfaces 53 and 54 to apply surfaces 53 and 54 with 
said adhesive substance. 
Each device 45, 46 comprises a known mechanical transmission 68 housed 
inside box element 47, 48 and presenting an output defined by a shaft 69 
fitted with disk 49, 50; and a mechanical transmission 70 presenting an 
output defined by a shaft 71 fitted with roller 57, 58. Each pair of 
transmissions 68 and 70 presents a common input comprising a single shaft 
72, which, together with shaft 72 of the other of devices 45 and 46, 
defines the output of a known actuating assembly 73 for simultaneously 
activating disks 49, 50 and rollers 57, 58 so that the directions of the 
tangential velocities of disks 49 and 50 at the points of contact with 
respective surfaces 43 are opposite to the traveling direction 17 of 
respective strips 5. 
Operation of machine 1 is clearly discernible from the foregoing 
description and therefore requires no explanation. It should be pointed 
out, however, that the arrangement of gumming unit 44 greatly simplifies 
any intervention on forming bed 9 on the part of the operator, as well as 
the assembly of removable safety covers (not shown) on the front surface 
10 side of bed 9. Moreover, the specific location of unit 44 along forming 
beam 28 provides for gumming the lateral portions 26 of the two strips 5 
downstream from station 18, and so preventing the formation of defective 
cigarettes (not shown) due to shreds of tobacco of respective layers 20 
adhering to lateral portions 26. 
The variation shown in FIGS. 4 and 5 relates to a gumming unit 74 
substantially similar to unit 44, except that, in this case, elements 47 
and 48 are combined into a single box element 75 enclosing two 
transmissions 70 located substantially one over the other on opposite 
sides of surface 31, and slightly offset in relation to each other in a 
direction perpendicular to direction 17. Moreover, the two pairs of 
transmissions 68 and 70 are activated by an actuating assembly 73, which, 
unlike actuating assembly 73 of unit 44, presents one output shaft 72 
connected to all four transmissions of unit 74. 
The above arrangement provides for gumming surfaces 43 substantially at the 
same point of beam 28 along path P. 
The variation shown in FIGS. 6 and 7 relates to a gumming unit 76 
substantially similar to unit 44, except that, in this case, box elements 
47 and 48, together with respective transmissions 70, are both located 
substantially over surface 31 and are offset in relation to each other 
along path P; appendixes 61 and 62 are both located on the same side of 
respective box elements 47 and 48; and, as opposed to being located one 
over the other, disks 49 and 50 are located substantially side by side and 
both beneath respective elements 47 and 48. 
As such, gumming devices 45 and 46 present substantially the same 
structure, which not only provides for simplifying the design and 
manufacture of devices 45 and 46, but also for storing fewer spare parts.