GB2167937A

GB2167937A - Cigarette production machine of the continuous rod type

Info

Publication number: GB2167937A
Application number: GB08529254A
Authority: GB
Inventors: Bruno Belvederi
Original assignee: GD SpA
Current assignee: GD SpA
Priority date: 1984-12-10
Filing date: 1985-11-27
Publication date: 1986-06-11
Also published as: FR2574255A1; DE3542612A1; IT8403651A0; GB8529254D0; IT1181267B

Abstract

Cigarette making machine comprises means for forming a continuous layer (14) of shredded tobacco on a suction belt (8) and means for transferring the layer from the belt and converting it into a continuous rod. The belt is caused to assume at least in its part near to the transferring means a curved cross-section with its concavity facing towards the rod forming means. <IMAGE>

Description

SPECIFICATION Cigarette production machine of the continuous rod type This invention relates to a cigarette production machine of the continuous rod type.

In production machines of the aforesaid type, it is known to feed a continuous layer of shredded tobacco on to a paper web, which is then fed through a forming bar, the purpose of which is to fold the opposing longitudinal edges of the paper web about the tobacco layer to form a continuous cigarette rod.

In production machines of the aforesaid type, it is further known to feed the said shredded tobacco layer on to the said paper web by a feed device consisting substantially of a conveyor comprising an endless air-permeable belt extending about end pulleys. The lower branch of said endless belt supports the tobacco layer by suction, and terminates immediately above a point on said paper web which is upstream of the forming bar.

In the aforesaid known feed device, the end pulleys of said tobacco conveyor are externally of cylindrical shape. Consequently, the permeable belt transported by them has a flat outer surface, and gives the tobacco layer a substantially rectangular cross-section.

The substantially rectangular shape of the tobacco layer deposited on to the paper web can lead to drawbacks during the formation of the rod along the forming bar. This is because considerable friction arises both within the tobacco itself and between the tobacco and its enclosing paper as the cross-section of the tobacco layer becomes transformed from rectangular to circular, and this friction is automatically converted into friction between the paper web and the surface of the forming bar, with the danger of tea ring the peper web.

The object of the present invention is to provide a cigarette production machine in which the forces acting on the paper web during the rod formation are reduced to the indispensable minimum.

Said object is attained according to the present invention by a cigarette production machine of the continuous rod type, comprising a forming station for a continuous cigarette rod; means for advancing a continuous paper web through said forming station, this latter comprising a forming bar engaged by said paper web and arranged to fold its lateral edges to give it a tubular shape; and a device for feeding shredded tobacco on to said paper web, said feed device comprising a suction conveyor belt converging towards a point on the path of said paper web disposed upstream of said forming bar, characterised by comprising support and guide means for said suction belt which are arranged to transversely deform this latter, at least along a portion thereof adjacent to said forming station, in such a manner as to give it an arcuate cross-section with its concavity facing towards said paper web.

The invention is described hereinafter with reference to the accompanying drawings, which illustrate some non-limiting embodiments thereof and in which: Figure 1 is a side elevational view, with parts shown in section and parts removed for clarity, of a cigarette production machine of the continuous rod type; Figure 2 is a diagrammatic illustration of a detail of Figure 1 and a series of sections taken along said detail in a first embodiment of the present invention; Figure 3 is a diagrammatic perspective view of a further detail of the embodiment shown in Figure 2; and Figures 4, 5 and 6 show series of sections corresponding to the sections of Figure 2 in three different further embodiments of the present invention.

In Figure 1,the reference numeral 1 indicates overall a cigarette production machine comprising two parts, the first of which is constituted by a substantially vertical duct 2, and the second of which is constituted by a section 3 comprising a base 4 delimited upperly by a surface 5.

The purpose of the section 3 is to form a continuous cigarette rod 6 and then to produce single cigarettes 7 by a cutting operation. Above the duct 2 and section 3, and connecting them together, there extends a shredded tobacco feed device comprising a suction conveyor belt 8 which is inclined downwards towards the section 3. The conveyor belt extends endlessly about clockwiserotating support and guide pulleys 9 and 10, and comprises a lower branch 11 which is inclined downwards towards the section 3 and of which the upper portion constitutes a closure elementforthe upper end of the duct 2.

The branch 11 slides between two downwardly extending lateral walls 12 (Figure 2) which together with the branch 11 define an advancement channel 13fora layer of shredded tobacco 14which is fed on to the branch 11 by the duct 2.

The layer 14 is kept in contact with the lower surface of the branch 11 by a suction device 15 comprising a chamber 16 disposed within the endless loop defined by the belt 8 and bounded lowerly by a perforated plate 17 disposed in contact with the upper surface of the lower branch 11 in orderto support and guide it between the pulleys 9 and 10. The suction device 15 also comprises a suction source, not shown, which is connected to the chamber 16 by a suction pipe 18.

The lower end of the lower portion of the branch 11 extends to a position 19, defined as the loading position, at which the tobacco layer 14 is fed to the section 3.

A device defined as the trimmer device and indicated overall by 20 is provided externally to the duct 2 in proximity to the branch 11, upstream of the loading position 19.

The loading position 19 is located at the point where the branch 11 converges with the upper branch 21, slidable on the surface 5, of a textile conveyor belt 22 which extends about end rollers 23 and 24 and is driven by a roller 25 which rotates in the anti-clockwise direction with reference to Figure 1.

The reference numeral 26 indicates a spool from which a web 27 of cigarette paper is unwound by advancement means constituted by the conveyor belt 22, and is deviated by a deviation roller 28 on to the branch 21 of the belt 22.

Above the loading position 19 there is a scraper plate 29, the inlet end or edge 30 of which cooperates with the lower surface of the branch 11 (not shown in Figure 3) at the periphery of the pulley 9 in order to detach the layer 14, and of which the lower surface 31 faces the surface 5 to progressively compress the layer 14 into contact with the paper web 27.

The section 3 also contains a forming station for the rod 6 comprising a forming bar 32, which is traversed by the web 27 and is arranged to fold its lateral edges about the layer 14 to form the rod 6, and a rotating blade 33 which divides the rod 6 into cigarettes 7. In all the embodiments shown in Figures2and 3 and in Figures4to 6, the pulley9 comprises along its outer cylindrical surface an annular groove 34, the base surface of which is curved with a circular profile. The groove 34 is engaged both by the belt 8, which flexes transversely into contact with said curved base surface, and by the inlet end 30 of the scraper plate 29.

The inlet end 30 is curved both towards the pulley 9, in such a manner as to substantially reproduce the inner profile of the groove 34, and towards the surface 5, and constitutes the inlet edge of an axial channel 35 formed by the surface 31 and tapering towards the bar 32.

In the embodiment shown in Figure 2, the pulley 10 has a cylindrical outer surface 36, and the perforated wall 17 is bounded lowerly by a flat surface 37, the inlet end of which is substantially tangential to the surface 36, and the outlet end of which is substantially tangential to the base of the groove 34. Consequently when in operation the branch 11 of the conveyor belt 8 slides in contact with the flat surface 37 to remain flat along the entire wall 17, and the tobacco layer 14 adhering to this branch retains a substantially rectangular shape limited upperly by the flat branch 11 and laterally by the walls 12. Only on reaching the pulley 9 does the conveyor belt 8 curve transversely into contact with the surface of the groove 34, to give a transversely curved shape to the upper surface of the layer 14.

This latter retains this upperly curved transverse shape even below the plate 29 and along the bar 32, to thus facilitate its wrapping by the paper web 27.

The embodiment shown in Figure 4 differs from the embodiment shown in Figure 2 and heretofore described, in that the wall 17 is bounded lowerly by a surface 38 of variable transverse curvature with its concavity facing downwards. Specifically, the radius of transverse curvature of the surface 38 is infinite at the inlet edge of the wall 17, and gradually reduces in the direction of the pulley 9, until it equals the radius of the cross-section of the groove 34.

Consequently, when in operation the branch 11 of the conveyor belt 8 becomes progressively curved transversely together with the upper surface of the layer 14 along the wall 17, until it attains its final transverse curvature determined by the groove 34.

The embodiment shown in Figure 5 differs from the embodiment shown in Figure 2 in that the pulley 10 also has an outer groove 39 substantially identical to the groove 34, and the wall 17 is bounded lowerly by a transversely curved surface 40 with its concavity facing downwards. The radius of transverse curvature of the surface 40 is constant along the entire length of the wall 17 and is equal to the radius of curvature of the cross-section of the grooves 34 and 39. Consequently, when in operation the branch 11 of the conveyor belt 8 and the upper surface of the layer 14 assume a transverse curvature which is constant along the entire wall 17 until the plate 29 is reached.

Finally, the embodiment shown in Figure 6 is substantially identical to the embodiment shown in Figure 5, from which it differs only in that the pulleys 9 and 10 are provided with grooves 41 and 42 which are deeper than the grooves 34 and 39, so as to accommodate a conveyor belt 8 which is wider than that used in the embodiments heretofore described.

In this manner, when the branch 11 of the conveyor belt 8 slides in contact with the lower surface 40 of the wall 17, its lateral edges make contact with the inner surfaces of the walls 12, to thus prevent any sliding ofthetobacco layer 14againstfixed surfaces.

In the embodiments shown in Figures 2 to 5, the lateral walls 12 comprise at their lower end, downstream of the duct 2, a depressed surface 43 to enable the trimmer device 20 to engage the tobacco layer 14. In the embodiment shown in Figure 6, the distance between the lower edges of the walls 12 must obviously increase in the zone of operation of the trimmer device 20, to allow a momentary flattening of the lower branch 11 of the belt 8.

Claims

1. A production machine for cigarettes of the continuous rod type, comprising a forming station for a continuous cigarette rod; means for advancing a continuous paper web through said forming station, this latter comprising a forming bar engaged by said paper web and arranged to fold its lateral edges to give it a tubular shape; and a device for feeding shredded tobacco on to said paper web, said feed device comprising a suction conveyor belt converging towards a point on the path of said paper web which is disposed upstream of said forming bar, characterised by comprising support and guide means for said suction belt which are arranged to transversely deform this latter, at least along a portion thereof adjacent to said forming station, in such a manner as to give it an arcuate cross-section with its concavity facing towards said paper web.

2. A machine as claimed in claim 1, characterised in that said suction conveyor belt is of endless configuration; said support and guide means comprise two end pulleys, the first disposed in a position adjacent to said forming bar and the second disposed in a position adjacent to a duct for feeding the tobacco to said suction conveyor belt, and a perforated section wall extending between two said pulleys and disposed with its lower surface in contact with the upper surface of the lower branch of said suction conveyor belt.

3. A machine as claimed in claim 2, characterised in that said first pulley comprises, along its outer surface, an annular groove of curved cross-section, the lower surface of said perforated wall being flat, and the outer surface of said second pulley being cylindrical.

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4. A machine as claimed in claim 2, characterised in that said first pulley comprises, along it outer surface, an annular groove of curved cross-section, the lower surface of said perforated wall being of curved cross-section, the radius of which varies, starting from that end of the perforated wall disposed adjacent to said second pulley, from infinity to a value equai to the radius of the crosssection of said groove of said first pulley, the outer surface of said second pulley being cylindrical.

5. A machine as claimed in claim 2, characterised in that each of said two pulleys comprises along its outer surface an annular groove of curved crosssection, the lower surface of said perforated wall being of curved cross-section, the radius of curvature of which is kept constantly equal, over the entire length of said perforated wall, to the radius of curvature of the cross-section of said grooves of said pulleys.

6. A machine as claimed in claim 5, characterised in that the inner surface of said perforated wall defines the base surface of a groove extending between said two pulleys and traversed by said suction conveyor belt; two walls disposed on opposite sides of said perforated wall defining the lateral surfaces of said groove; said suction conveyor belt having a width greater than the width of said perforated wall, and comprising, extending along said groove, a portion which is disposed with opposing lateral zones in contact with said lateral walls

7. A machine as claimed in any one of claims 2 to 6, characterised by further comprising a scraper plate disposed beween said forming bar and said tobacco feed device; said plate having a curved inlet edge which is disposed in engagement with the annular groove of said first pulley.

8. A cigarette production machine of the continuous rod type, substantially as described with reference to any one of the figures of the accompanying drawings.