WO2000013533A1

WO2000013533A1 - Apparatus for forming a tobacco stream

Info

Publication number: WO2000013533A1
Application number: PCT/GB1999/002852
Authority: WO
Inventors: Michael James Dann; Darren Simmons; Stephen Douglas Puddephatt
Original assignee: Molins Plc
Priority date: 1998-09-04
Filing date: 1999-08-31
Publication date: 2000-03-16
Also published as: GB9819404D0

Abstract

Apparatus for forming a stream of tobacco comprises an endless air-permeable band (14), a suction chamber (34) from which suction is applied to one side of a lower reach of the band whereby tobacco can be attracted to and held on the opposite side of the lower reach, opposed walls (16, 18) which with the band define a channel (20) along which tobacco is transported by the band and displacers (70) for selectively displacing the lower reach of the band in a direction transverse to its direction of travel for displacing choke tobacco in the channel.

Description

Apparatus for Forming a Tobacco Stream

The invention relates to cigarette making and in particular to apparatus for forming a tobacco stream which can be shaped to form a cigarette filler rod. In conventional cigarette making machines, tobacco from a primary source is received in a hopper where it is subjected to a winnowing process prior to being discharged into an upwardly extending duct along which it is carried by a rising air stream. Downstream of the duct, an air-permeable band has its lower reach arranged so as to be in the path of tobacco exiting the duct. Suction is applied to the band which attracts and holds the tobacco to form a stream of tobacco which is carried away from the duct past a trimming device and then delivered to a rod forming device at which a paper web is wrapped around the trimmed tobacco to form a cigarette rod.

The band is typically arranged between guide rails, which may support the band, and these rails together with the underside of the lower reach of the band define a relatively narrow channel in which the tobacco stream is formed. Typically, the nominal width of the channel is in the range 8 to 10 mm.

One problem which is encountered in the operation of cigarette machines is that the narrow passages such as the channel in which the tobacco stream is formed may become blocked by lumps of tobacco. Once a passage becomes blocked in this way it is necessary to stop the cigarette machine and clear the blockage. It goes without saying that this is undesirable and that cigarette manufacturers would wish that the time required to clear choked passages is minimised.

Typically, blockages which occur in the channel in which the tobacco stream is formed are cleared by raising the suction band and guide rails to provide access to the channel and then inserting a long rod into the channel to clear the blockage.

The upper side of the lower reach of the band, i.e the side to which suction is applied, may be supported by skids or a plurality of rollers, the rollers being arranged in spaced apart relationship along the length of the band. The rollers are mounted on horizontally disposed axles the ends of which are supported by respective side walls. The side walls define a space for the rollers which is marginally wider than the width of the rollers. A problem that occurs when the band is supported by such an arrangement of rollers is that excess flavouring sauce added to the tobacco can coagulate in the narrow spaces around the rollers causing them to stick. Additionally, deposits of tobacco may adhere to the rollers or the member or members on which they are mounted. These deposits of flavouring sauce or tobacco can lead to an unsatisfactory operation of the suction band and premature wear of the rollers.

It is known to provide scrapers adjacent the rollers to prevent the build-up of deposits on the rollers. However, this requires the provision of additional parts and it is necessary to check the distance between the rollers and the respective scrapers on a regular basis and reset the gap where necessary in order for the arrangement to be effective.

The invention provides apparatus for forming a stream of tobacco, the apparatus comprising an endless air-permeable band, means for applying suction to one side of a lower reach of the band whereby said tobacco can be attracted to and held on the opposite side of the lower reach, means defining generally opposed walls which with said opposite side define a channel along which said tobacco is transported by the band and means for selectively displacing said lower reach of the band in a direction transverse to its direction of travel for displacing choke tobacco in said channel. The invention also includes a method of clearing choke tobacco from a channel in a cigarette making machine which channel is defined by spaced apart wall elements and an air-permeable band disposed therebetween, the method comprising deflecting said band in a direction transverse to the lengthwise direction of said channel so as to push said choke tobacco in the general direction of said deflection. The invention also includes apparatus for use in forming a stream of tobacco, the apparatus comprising an endless air-permeable band, means for applying suction to one side of said band whereby particulate material can be attracted to and held by said band for transport by the band and a plurality of tapered rollers arranged in spaced apart relationship in the lengthwise direction of the band so as to bear against said one side, the arrangement being such that the axis of rotation of each said roller is inclined to the plane of said one side of the band.

The invention also includes a roller device for supporting an air-permeable band in a cigarette making machine, the device comprising a member which defines at least one mounting for a tapered roller and at least one tapered roller mounted at the or each said mounting, the or each roller defining a bearing surface having a length in the axial direction of the roller and against which, in use, said air-permeable band is drawn by suction such that one side of the band bears against the or each said surface and being arranged such that the axis of rotation of the or each roller is inclined such that the or each bearing surface can bear against said one side of the band over substantially the entire said length.

In order that the invention may be well understood, some embodiments thereof, which are given by way of example only, will now be described with reference to the drawings, in which:

Figure 1 is an end elevational view of apparatus for forming a stream of tobacco in a cigarette making machine;

Figure 2 is a section on line II-II in Figure 1 ;

Figure 3 is an enlarged view of a portion of Figure 2 showing a band displacing mechanism;

Figure 4 is an enlarged perspective view of an air vane arrangement for the apparatus shown in Figure 1 ;

Figure 5 is a section view on line V-V in Figure 2 showing the position of the air vane arrangement; Figure 6 is a partly broken away perspective view of a roller box for apparatus for forming a stream of tobacco; and

Figure 7 is a section view on line Nil- VII in Figure 5.

An embodiment of an apparatus 10 for forming a stream of tobacco for cigarette rod making is illustrated by Figures 1 to 5 and is shown in Figure 2 positioned at the downstream end of an upwardly extending chimney 12. Winnowed tobacco from a hopper (not shown) is caused to travel up the chimney by a rising air current.

The apparatus 10 comprises an endless air-permeable band 14 the lower reach of which is situated between opposed side members 16,18 (Figure 5). The band may be made of woven nylon or other suitable flexible material. The side members act as guides for the band 14 and together with the underside of the lower reach of the band define a channel 20 which extends transversely of the chimney. The band is carried by two pulleys 24, 26 which are disposed at opposite ends of the apparatus 10.

The side members 16, 18 may each comprise a number of elongate elements disposed in end-to-end relationship and are arranged such that, as viewed in Figure 2, the upstream end of the channel 20 is disposed at the right-hand side of the chimney 12 and the downstream end is coterminous with the pulley 24.

As shown in Figure 5, the side members 16, 18 are spaced apart a distance corresponding substantially to the width of the band and the arrangement is such that the region of the channel adjacent the band is rectangular in cross-section. Preferably, the channel is approximately 8mm wide. The opposing faces of the side members 16, 18 are relieved at 28 to define a tapered cross-section lead-in to the channel 20 such that the tobacco leaving the chimney is guided gently into the channel.

The pulley 26 has a larger diameter than the pulley 24 thereby providing a greater lap angle which allows more torque to be transmitted to the band. In the illustrated embodiment the pulley 24 has a diameter of 39mm and the diameter of the pulley 26 is 78mm. The pulleys are connected with the drive shafts of respective servo motors 30, 32 (Figure 1). The servo motors are independent of one another and are operated at different rotational speeds so that the peripheral surfaces of the pulleys which engage the band rotate at the same speed.

A tensioning system (not shown) is provided for tensioning the band 14. The tensioning system comprises a hydraulic or pneumatic cylinder which acts against the pulley 26 in a direction which tensions the band (to the right as viewed in Figure 2) and a spring which acts in the opposite direction. The spring is a tension spring and the arrangement is such that, in use, as the band length increases (by creep) the resultant force exerted on the band by the combination of the cylinder and spring reduces thereby improving band life. When the machine is not running, the tensioning system retracts to relieve the band tension.

The air rising in the chimney is drawn through the band into a suction chamber 34 which is connected with a fan (not shown).

A series of skids 40 are arranged along the length of the channel 20 above the lower reach of the band 14. Skids are devices well known to those skilled in the art and will not be described in detail herein. Alternatively, an arrangement of conventional roller boxes may be used instead of skids. As a further alternative, roller boxes as described hereinbelow with reference to Figures 6 and 7 may be used. As is well known, the skids or rollers provide support for the uppermost side of the lower reach of the band when as described in more detail below, suction is applied to the band.

A trimming device (not shown) such as, for example, the device disclosed in our PCT/GB98/01011 is located at 42 in order to trim the stream of tobacco conveyed along the channel 20. Trimming is a process well known to those skilled in the art and will not be described in further detail herein.

A duct 44 is provided beneath the trimming device to receive the so-called ecretage tobacco removed from the channel 20 by the trimming device. The duct has an outlet end 46 (Figure 1) which may be connected with a suitable ducting system to permit the return of the ecretage tobacco to the hopper. Such a system is described in our patent application GB9802861.6 the content of which is incorporated herein by reference.

In the usual way, a tongue and shoe and a garniture tape (not shown) are provided at the downstream end of the channel 20. A suitable arrangement is, for example, disclosed in our WO98/27833.

An air vane arrangement 50, indicated generally in Figure 2, is provided in the region of the erectage return duct 44. The vane arrangement is best seen in Figures 4 and 5 and comprises a mounting block 52 on which are mounted a plurality of inclined plate-like vanes 54. In the operating position of the vane arrangement, the vanes are inclined to the horizontal at approximately 30 degrees and as viewed in Figure 5, their uppermost ends are directed towards the downstream end of the channel 20. A spigot 56 extends from the rear of the mounting block 52. A shaft 58 which is rotatably mounted in bearings 60 (Figure 5) extends from the spigot 56. The upper side 62 of the mounting block bears against the underside of the side member 16. The spigot 56 is located off centre of the mounting block 52 such that absent the restraining force provided by the side member 16, the mounting block will rotate anti-clockwise (as viewed in Figure 2) under the influence of gravity; the rotation of the mounting block may be spring assisted. The function of the vane arrangement is to provide rapid pressure equalisation between the chimney pressure which is below atmospheric and the pressure in the duct

40 in the region of the trimming device and thereby prevent air in the ducting rushing upstream in the channel 20 towards the chimney. The arrangement of the vanes 54 provides a forward component to the ambient pressure air drawn into the duct 44.

A plurality of band displacers, indicated generally in Figure 2 by reference numeral 70, are provided at regular intervals along the length of the band. The band displacers at the downstream end of the band are not shown for the purpose of clarity of the drawing.

As shown in Figure 3, the band displacers 70 comprise an arm 72 which extends from an annular body 74 which is mounted so as to be rotatable by means a pneumatic actuator 76. The arm 72 is slightly cranked with respect to the body 74 so as to define a snail camming surface 78. The skids 40, or where roller boxes are used, the roller boxes, are arranged such that the displacers 70 can be mounted above the lower reach of the band 14 with their camming surfaces 78 bearing against the side of the lower reach which is remote from the channel 20. The actuators 76 are arranged to rotate the arms 72 anti-clockwise approximately 90 degrees from a generally horizontal position to the generally vertical position which is indicated in Figure 3 by dashed lines. As the arm so rotates, the camming surface 78 displaces the band in a downwards direction which is transverse to the direction of travel of the band. It will be appreciated that any suitable type of actuator such as an electrically powered actuator may be used instead of the pneumatic actuator 76.

A housing 80 which defines the suction chamber 34 is slideably mounted to a cigarette making machine frame 82 by means of Hepco slides 84. Hepco slides can be obtained from Hepco Slide Systems Limited of Lower Moor Business Park, Tiverton Way, Tiverton, EX16 6TG, United Kingdom. A pneumatic cylinder 86 has its upper end connected to the frame 82 and its lower end connected to the housing 80 so as to be actuable to raise and lower the housing relative to the machine frame 82 on the slides 84.

In the normal use, tobacco is guided upwardly in the chimney 12 and into the charmel 20 where it is held against the underside of the band 14 by suction from the suction chamber 34. The tobacco held against the band forms a generally rectangular cross-section stream of tobacco which is conveyed along the channel 20 towards the trimming device where the height of the tobacco stream is reduced as required. The trimmed tobacco stream is conveyed to the downstream end of the channel where it is scraped off the band by the shoe and is then taken up by the garniture to be shaped and formed into a cigarette rod. The above-described process is conventional and will be familiar to those skilled in the art.

In the event that the channel 20 becomes choked by a lump, or lumps, of tobacco, the cigarette making machine is stopped and the pneumatic cylinder 86 is actuated to cause the suction chamber housing 80 to rise on the slides 84. The upward movement of the housing 80 carries the channel 20 away from the chimney 12 and duct 44. As the housing is raised, the actuators 76 cause the arms 72 of the band displacers 70 to press the band downwardly in the channel 20 so that the tobacco blocking the channel is pushed out of the relatively narrow rectangular cross section channel into the tapered lead-in channel from which it can be readily removed. This tobacco can either be collected manually by the operator or returned pneumatically to the hopper using an arrangement such as that described in our GB9802861.6. Protection for that arrangement in combination with apparatus such as the apparatus 10 may be sought in this application. When the suction chamber housing 80 is raised, the side member 16 is lifted away from the air vane mounting blocks 52. Consequently, the mounting block rotates anti clockwise under the influence of gravity with the block assuming a generally vertical position. In this position, the possibility of choke tobacco falling from the channel 20 and blocking the spaces between the vanes 54 is avoided.

Once the blockage is cleared, the suction chamber housing 80 is returned to its operating position by means of the pneumatic cylinder 86 and the arms 72 are returned to a generally horizontal condition by the respective actuators 76 so that the band 14 moves back into contact with the skids 40. A roller box 110 which may advantageously be used with the apparatus 10 is shown in Figures 6 and 7. The roller box 10 is shown mounted on elongate roller housing member 112 which is shown mounted on side members 116, 118 which together with an air-permeable band 114 define a channel 120 for tobacco corresponding to the channel 20 described hereinabove. The roller box 110 includes a housing member 112 which is provided with a plurality of through-holes 128. The through-holes extend from an upper surface 130 to the opposing lower surface of the member 112 and are arranged in a regular spaced apart relationship along the length of the member.

Each through-hole 128 houses a tapered ceramic roller 132. The rollers 132 are mounted cantilever fashion on respective stub axles 134. The axles are non-rotatably mounted in respective through-bores which extend transversely of the through-holes 128. The arrangement is such that alternate rollers 132 project in opposed directions.

As best seen in Figure 7, the axles 134 are inclined to the vertical such that respective band engaging faces 136 of the tapered rollers 132 lie in the plane of the band 114. In the illustrated embodiment, the axles 134 are inclined at an angle of approximately 10 degrees to the plane of the band 114. The width of the engaging faces 136 is substantially the same as the width of the band so that the rollers support the band over its entire width.

The through-holes 128 have a generally rectangular cross-section and are approximately as wide as the band 114. In fact they are slightly wider than the band so as to provide clearance for the rollers 132 which are preferably as wide as the band. Each through-hole 128 includes a tapered recess 140 arranged to complement the inclination of the rollers 132. The inclined face 142 of each recess is substantially perpendicular to the axis of rotation of the tapered rollers. In use the roller box 110 functions in the same way as a conventional roller box. However, problems of sticking and wear of the rollers by accumulations of tobacco and/or tobacco sauce are considerably reduced. As best seen in Figure 7, the inclination of the rollers provides an increased clearance between the rollers and the walls of the through-holes in which they are housed. Additionally, the engaging faces 136 of the rollers are kept clean by a scuffing action caused by the difference in the surface speed across the width of the roller.

It will be appreciated that there is provided in the apparatus 10, a system for tensioning an air-permeable band in which a fluid cylinder provides a substantially constant tensioning force which acts to tension the band and a biassing force which acts against said tensioning force whereby, in use, as the band length increases, the force exerted on the band by the system reduces.

Claims

1. Apparatus for forming a stream of tobacco, the apparatus comprising an endless air-permeable band, means for applying suction to one side of a lower reach of the band whereby said tobacco can be attracted to and held on the opposite side of the lower reach, means defining generally opposed walls which with said opposite side define a channel along which said tobacco is transported by the band and means for selectively displacing said lower reach of the band in a direction transverse to its direction of travel for displacing choke tobacco in said channel.

2. Apparatus as claimed in claim 1, wherein said displacing means operates on said one side of the band

3. Apparatus as claimed in claim 2, wherein said displacing means comprises a plurality of members arranged in spaced apart relationship in the lengthwise direction of said band.

4. Apparatus as claimed in claim 3, wherein said members are rotatable for displacing said band.

5. Apparatus as claimed in claim 4, wherein each rotatable member comprises a snail cam.

6. Apparatus as claimed in claim 4 or 5, comprising respective pneumatic actuators for said rotatable members.

7. Apparatus as claimed in any one of the preceding claims, wherein said band, wall defining means and displacing means are carried by a housing which is adapted to be slideably mounted to a cigarette making machine.

8. Apparatus as claimed in claim 7, wherein said housing defines a suction chamber.

Claims

9. Apparatus as claimed in any one of the preceding claims, wherein said band is mounted on two pulleys disposed one at each end region of said channel and connected with respective independent servo motors.

10. Apparatus as claimed in claim 9, wherein the said pulley disposed at the upstream end region of the channel has a greater diameter than the other said pulley.

11. Apparatus as claimed in any one of the preceding claims, comprising means for engaging said one side of the lower reach of the band, said engaging means comprising a plurality of tapered rollers arranged with the axis of rotation of each roller inclined to the plane of the band.

12. A method of clearing choke tobacco from a charmel in a cigarette making machine which channel is defined by spaced apart wall elements and an air-permeable band disposed therebetween, the method comprising deflecting said band in a direction transverse to the lengthwise direction of said channel so as to push said choke tobacco in the general direction of said deflection.

13. A method as claimed in claim 12, comprising the step of deflecting said band by applying a deflecting force to the band at a plurality of locations which locations are spaced apart in said lengthwise direction of the channel.

14. Apparatus for use in forming a stream of tobacco, the apparatus comprising an endless air-permeable band, means for applying suction to one side of said band whereby particulate material can be attracted to and held by said band for transport by the band and a plurality of tapered rollers arranged in spaced apart relationship in the lengthwise direction of the band so as to bear against said one side, the arrangement being such that the axis of rotation of each said roller is inclined to the plane of said one side of the band.

15. Apparatus as claimed in claim 11 or 14, wherein each said roller has a width and contacts said one side of the band over substantially the entire said width.

16. Apparatus as claimed in claim 11, 14 or 15, comprising an elongate member provided with at least one recess for housing a said roller, one said wall of the recess having a bore for an axle for the roller and at least a portion of an opposite side wall being inclined to said plane of said one side of the band.

17. Apparatus as claimed in claim 16, wherein said wall partially defines a recess which is inclined to said plane of said one side of the band.

18. Apparatus as claimed in claim 16 or 17, wherein said wall is inclined so as to be substantially perpendicular to said axis of rotation.

19. Apparatus as claimed in any one of claims 11 or 14 to 18, wherein said tapered rollers are cantilever mounted.

20. Apparatus as claimed in any one of claims 11 or 14 to 19, wherein said rollers are arranged such that the respective axes of rotation of adjacent rollers are inclined in different directions.

21. A roller device for supporting an air-permeable band in a cigarette making machine, the device comprising a member which defines at least one mounting for a tapered roller and at least one tapered roller mounted at the or each said mounting, the or each roller defining a bearing surface having a length in the axial direction of the roller and against which, in use, said air-permeable band is drawn by suction such that one side of the band bears against the or each said surface and being arranged such that the axis of rotation of the or each roller is inclined such that the or each bearing surface can bear against said one side of the band over substantially the entire said length.

22. A device as claimed in claim 21, wherein the or each roller is housed in a through-hole defined by said member.

23. A device as claimed in claim 22, comprising a plurality of rollers and respective said through-holes for said rollers.

24. A device as claimed in claim 23, wherein said rollers are arranged such that the respective axes of rotation of adjacent rollers are inclined in opposite directions.

25. A device as claimed in claim 24, wherein the axes of rotation of said adjacent rollers are inclined at the same angle.

26. A device as claimed in any one of claims 21 to 25, wherein the or each roller is mounted on a stub axle which extends from said member as a cantilever.

27. A device as claimed in claim 26 when dependent on claim 22 or 23, wherein the or each through-hole defines a first wall which, in use, is substantially perpendicular to the plane of the band and a second wall at least a portion of which is inclined so as to be substantially perpendicular to the axis of rotation of the roller housed therein.

28. A device as claimed in any one of claims 21 to 27, wherein the or each said bearing surface is defined by a ceramic material.

29. A cigarette making machine comprising apparatus as claimed in any one of claims 1 to 11 or 14 to 20, or a device as claimed in any one of claims 21 to 28.

30. Apparatus for transporting a stream of tobacco, said apparatus comprising an elongate trough having an upstream end, an endless band arranged to transport tobacco from said upstream end along said trough and at least one device for selectively moving at least a portion of said band in a direction transverse to a lengthwise direction of said trough for displacing tobacco blockages in said trough.