GB2258133A

GB2258133A - Cigarette rod production

Info

Publication number: GB2258133A
Application number: GB9214344A
Authority: GB
Inventors: Bruno Belvederi
Original assignee: GD SpA
Current assignee: GD SpA
Priority date: 1991-07-11
Filing date: 1992-07-06
Publication date: 1993-02-03
Anticipated expiration: 2012-07-06
Also published as: GB2258133B; IT1252419B; DE4221813A1; ITBO910247A1; GB9214344D0; ITBO910247A0

Description

2 23 j l 33 METHOD AND MACHINE FOR PRODUCING CONTINUOUS CIGARETTE RODS The

present invention relates to a method of producing continuous cigarette rods.

On cigarette manufacturing machines, continuous cigarette rods are produced by first forming a paper-tobacco assembly consisting of a continuous flat strip of paper on to which a layer or stream of shredded tobacco is fed. The assembly so formed is theri-fed on to a forming beam, which folds the continuous paper strip substantially in a U about its longitudinal axis, so that it presents a semicylindrical central longitudinal portion housing the shredded tobacco, and two parallel lateral longitudinal portions, with no tobacco, on either side of the central portion. ' At this point, an inner end surface portion of one of the lateral portions is coated with gum, and the strip fed forward so as to successively engage two folding devices, which fold the lateral portions towards each other, so that the gummed end portion overlaps a corresponding end portion of the other lateral portion.

The above known method presents several drawbacks, mainly due to the gum used for joining the two longitudinal ends of the continuous paper strip.

Firstly, setting of the gum is highly sensitive to ambient temperature and humidity, which may result in partial or total detachment of the joint; and, secondly, combustion of the gum results in the formation of substances which, when inhaled, may prove particularly harmful to the health of the user.

It is an object of the present invention to provide a method designed to at least partially eliminate the above drawbacks.

According to the present invention, there is provided a method of producing a continuous cigarette rod, said method comprising stages consisting in feeding a continuous strip of paper supporting a layer of shredded tobacco along a folding path along which the paper strip is folded about its longitudinal axis so as to bring two longitudinal portions of the strip into contact with each other and so define a cylindrical tubular wrapping housing said shredded tobacco; and in connecting said two longitudinal portions so as to form said tubular wrapping; characterized by the fact that said two longitudinal portions are folded into contact with each other in such a manner as to project substantially radially outwards of said tubular wrapping; said two longitudinal portions being connected by mechanically pressing them together; and said two integral longitudinal portions then being folded down on to said tubular wrapping and stabilized in said downfolded position.

The present invention also relates to a cigarette manufacturing machine implementing the method as described above.

According to the present invention, there is provided a machine for producing a continuous cigarette rod, said machine comprising a unit for forming said continuous rod, and a conveyor for feeding a continuous strip of paper supporting a layer of shredded tobacco to said forming unit; said forming unit comprising first folding means for folding the continuous strip about its longitudinal axis so as to bring two longitudinal portions of the continuous strip into contact with each other and so define a cylindrical tubular wrapping housing said shredded tobacco; and connecting means for connecting said two longitudinal portions and so forming said tubular wrapping; characterized by the fact that said first folding means are so designed as to fold said two longitudinal portions into contact with each other in a substantially radial position in relation to said tubular wrapping; and by the fact that said connecting means are pressure means for mechanically compressing and joining said two longitudinal portions; second folding means being provided for folding said two integral longitudinal portions down on to said tubular wrapping; and stabilizing means being provided for securing said two longitudinal portions in said downfolded position.

A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings,, in which:

Fig.1 shows a schematic, partially sectioned side view, with parts removed for clarity, of a cigarette manufacturing machine implementing the method according to the present invention; Fig.2 shows a section along line II-II in Fig.1; Fig.3 shows a section along line III-III in Fig.1; Fig.4 shows a section along line IV-IV in Fig.l.

Number 1 in Fig.1 indicates a cigarette manufacturing machine comprising a unit 2 for forming a continuous cigarette rod 3; and a known unit 4 for forming and supplying to unit 2 a continuous layer 5 of shredded tobacco.

On unit 4, shredded tobacco is fed in known manner along a substantially vertical duct 6, so as to form layer 5 on the underside of a suction conveyor belt 7. As it travels towards unit 2, layer 5 is shaved in known manner, to even out the thickness, by known shaving devices 8 (only one of which is shown), and is fed, at loading station 9, on to a continuous paper strip 10 traveling along a conveyor 11 on unit 2.

As shown in Fig.1, unit 2 comprises a so-called rod forming beam 12 along which the belt 13 of conveyor i 1 11 extends, and which defines a path along which strip 10 is folded longitudinally about layer 5.

As shown in Fig.2. beam 12 constitutes a folding device for folding belt 13 in the form of an upwardly-concave U, for which purpose, beam 12 comprises a bottom plate 14, the initial portion of which (not shown) adjacent to loading station 9 is perfectly flat and arranged contacting the underside of belt 13. Further along said folding path from loading station 9. the upper surface 15 of plate 14 presents a groove 16 extending along the folding path, beneath belt 13, and which gradually increases in depth until it eventually presents a semicircular section (Fig.2), which remains constant up to the opposite end of beam 12 to loading station 9.

Beam 12 also comprises two top plates17 and 18 contacting surface 15 of plate 14 on either side of the semicircular-section portion of groove 16. Plates 17 and 18 present respective facing lateral surfaces 19 and 20 initially arranged (in known manner not shown) perpendicular to surface 15 and separated by a distance equal to the diameter of groove 16. and which gradually change shape, along the folding path, so as to eventually present, along an intermediate portion 21 of plates 17 and 18, a curve (Fig.2) extending over an arc of the same radius as groove 16. More specifically, in their final form, surfaces 19 and 20 define with groove 16 a substantially cylindrical conduit 22, and present respective straight parallel top edges substantially contacting each other and defining a straight opening 23 through which conduit 22 communicates laterally with the outside.

Over intermediate portion 21 of plates 17 and 18, there is provided a pressure unit 24 comprising" two knurled rollers 25 rotated by a drive unit 26 in opposite directions about respective parallel axes perpendicular to surface 15. Rollers 25 are arranged tangent to each other over and in a plane through opening 23, and are driven by unit 26 so as to rotate, at the point of tangency, parallel to and in the same direction as belt 13 along beam 12, and at a surface speed equal to the speed of belt 13.

Downstream from intermediate portions 21 in the traveling direction of belt 13 along beam 12, plates 17 and 18 comprise-respective end portions 27 and 28 having respective facing lateral surfaces 29 and 30 in the form of cylindrical surface portions of the same radius as conduit 22, the first extending over an arc of more than 90% and the second over an arc of less than 90 and not necessarily complementary to the first.

As shown in Fig.s 1 and 3, along beam 12, between end portions 27, 28 of plates 17, 18 and a known cutting head 31 at the opposite end of beam 12 in relation to loading station 9, there is provided a stabilizing unit 32 comprising a nozzle 33 for supplying steam radially on to rod 3; and a pressing member 34 for exerting a given radial pressure on the portion of rod 3 swept by the steam jet from nozzle 33.

In actual use, belt 13, traveling along beam 12 together with strip 10 and tobacco layer 5, gradually engages groove 16, by which it is folded, together with strip 10, into an upwardly-concave U about its longitudinal axis, which folding process is continued further upon belt 13 and strip 10 contacting lateral surfaces 19 and 20 of plates 17 and 18. Morespecifically, on contacting lateral surfaces 19 and 20 of intermediate portions 21 of plates 17 and 18, and on engaging conduit 22, strip 10 is folded transversely into a loop about layer 5, so that two longitudinal portions 35 project outwards of conduit 22 through opening 23, and are engaged contacting each other between rollers 25.

The pressure exerted by rollers 25 provides for mechanically joining portions 35 and so forming, without the use of adhesive substances, a closed tubular wrapping 3a having a rib 36 extending substantially radially outwards.

As it travels towards cutting head 31, rib 36 (Fig.3) engages lateral surface 29 of end portion 27 of plate 17, by which it is folded laterally on to outer lateral surface 37 of tubular wrapping 3a.

On leaving plates 17 and 18, rib 36 is secured in the downfolded position by stabilizing unit 32, the pressing member 34 of which provides for exerting a given pressure on wrapping 3a for shaping it into the substantially cylindrical finished form of rod 3.

Claims

1) A method of producing a continuous cigarette rod (3), said method comprising stages consisting in feeding a continuous strip of paper (10) supporting a layer of shredded tobacco (5) along a folding path along which the paper strip (10) is folded about its longitudinal axis so as to bring two longitudinal portions (35) of the strip (10) into contact with each other and so define a cylindrical tubular wrapping (3a) housing said shredded tobacco; and in connecting said two longitudinal portions (35) so as to form tubular wrapping (3a); characterized by the fact said two longitudinal portions said that (35) are folded into contact with each other in such a manner as to project substantially radially outwards of said tubular wrapping (3a); said two longitudinal portions (35) being connected by mechanically pressing them together; and said two integral longitudinal portions (35) then being folded down on to said tubular wrapping (3a) and stabilized in said downfolded position.

2) A method as claimed in Claim 1, characterized by the fact that said two longitudinal portions (35) are subjected to a steam jet and subsequently pressed for securing them in said downfolded position.

3) A machine (1) for producing a continuous cigarette rod (3), said machine (1) comprising a unit (2) for forming said continuous rod (3), and a conveyor (11) for feeding a continuous strip of paper (10) supporting a layer of shredded tobacco (5) to said forming unit (2); said forming unit (2) comprising first folding means (12) for folding the continuous strip (10) about its longitudinal axis so as to bring two longitudinal portions (35) of the continuous strip (10) into contact with each other and so define a cylindrical tubular wrapping (3a) housing said shredded tobacco; and connecting means (24) for connecting said two longitudinal portions (35) and so forming said tubular wrapping (3a); characterized by the fact that said first folding means (12) are so designed as to fold said two longitudinal portions (35) into contact with each other in a substantially radial position in relation to said tubular wrapping (3a); and by the fact that said connecting means are pressure means (24) for mechanically compressing and joining said two longitudinal portions (35); second folding means (27) being provided for folding said two integral longitudinal portions (35) down on to said tubular wrapping (3a); and stabilizing means (32) being provided for securing said two longitudinal portions (35) in said downfolded position.

4) A machine as claimed in Claim 3, characterized by the fact that said first folding means comprise a forming beam (12) defining a conduit (22) for forming said tubular wrapping (3a); said conduit (22) presenting an axial lateral opening (23) by which it communicates externally; said opening (23) being engaged by said portions (35); and said pressure means (24) being located adjacent to said opening (23).

5) A machine as claimed in Claim 4, characterized by the fact that said pressure means (24) comprise a pair of knurled rollers (25) adjacent to said opening (23) and substantially tangent to each other in a plane through the same, for engaging and mechanically joining said two portions (35) and so forming a rib (36) extending substantially radially from said tubular wrapping (3a).

6) A machine as claimed in Claim 5, characterized by the fact that said forming beam (12) comprises a bottom plate (14) having, along at least part of its length, a semicircular-section groove (16) defining the bottom portion of said conduit (22); and two top plates (17, 18) on either side of said groove (16), having respective curved lateral surfaces (19, 20) facing each other and defining the top portion of said conduit (22); said two lateral surfaces (19, 20) presenting respective facing edges defining said opening (23).

7) A machine as claimed in Claim 6, characterized by the fact that said second folding means are defined by the end portion (27) of a first (17) of said two top plates (17, 18); said end portion (27) of said first top plate (17) presenting a curved lateral surface (29) extending over an arc of more than 90 about the axis of said groove (16), for folding said rib (36) down on to the outer surface (37) of said tubular wrapping (3a).

8) A machine as claimed in Claim 7. characterized by the fact that said stabilizing means (32) comprise steam supply means (33) for directing steam on to said downfolded rib (36); and pressing means (34) cooperating with said steam supply means (33), for pressing said downfolded rib (36) on to said outer surface (37) of said tubular wrapping (3a).

9) A method of producing a continuous cigarette rod, substantially as described and illustrated herein with reference to the accompanying drawings.

10) A machine for producing a continuous cigarette rod, substantially as described and illustrated herein with reference to the accompanying drawings.

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