APPARATUS AND METHOD FOR FORMING A ROD OF SMOKEABLE MATERIAL

Abstract: Apparatus and method of forming a rod of tobacco from two types of tobacco in which the two types (A, B) are stored in a hopper (12) and separated therein by a partition (14), and deposited on an air pervious conveyor belt (16) so that one type (B) overlies the other type (A). Deposition of one type (A) on the belt is periodically inhibited in favour of the other type (B) by means of an air jet (32) directed at the belt.

Description: This invention relates to the manufacture of a rod of smokeable material, such as is used in cigarettes, and is concerned with the production of a rod in which the smokeable material consists of more than one type of smoking material, in particular a rod in which the types of smoking material are demarcated. The types of smoking material envisaged in the present invention include those exhibiting different natures or compositions and may, for instance, comprise various types of tobacco, tobacco products such as reconstituted tobacco, or tobacco substitutes. For the purposes of this invention, "tobacco substitute" includes not only smokeable materials such as cellulose derivatives but inert fillers such as alumina. In is known in prior art DE-A-2259814 to provide a cigarette making machine for making cigarettes consisting of two demarcated smoking materials of different compositions. The machine of the prior art includes an air-pervious conveyor belt, a vacuum source on one side of the belt, and two charging appliances for the smoking materials. The charging appliances are arranged to deposit respective materials on the other side of the belt, one on top of the other. They include devices for imparting shape to the tow of one of the smoking materials when on the conveyor, and devices for the removal of surplus material. The smoking material supplied to each charging appliance and further conveyed to the conveyor belt is controlled by two cutting and return devices, one for each charging appliance. The cutting devices are profiled disc cutters. There are further provided a blow separating device, a cleaning disc and a vibratory conveyor capable of dealing with 50% or more excess material. A disadvantage of the machine of DE-A-2259814 is that there is appreciable degradation of material by the cutting and return devices. The present invention utilises conventional cigarette making machinery, such as the Molins "Mark 8", with a conventional charging device and a vacuum conveyor, but renders unnecessary the trimming or removal of the first deposited material from the vacuum conveyor, thereby obviating the degradation and return of the material. According to a first aspect of the present invention, there is provided apparatus for forming a rod of smokeable material from at least two types of smokeable material, comprising storage means for storing said at least two types of smokeable materials, an air pervious conveyor belt, a vacuum source located on one side of the belt, tobacco depositing means located on the other side of the belt, said tobacco depositing means comprising a first tobacco depositing zone and _ seen in the direction of movement of the conveyor _ a subsequent second tobacco depositing zone for continuously and uninterruptingly depositing first and second types of smokeable materials respectively on the belt so that the second type of smoking material overlies the first type, characterised in that the first tobacco depositing zone is arranged adjacent to the second tobacco depositing zone, and in that there are provided gate means to prevent, when activated, smokeable material of the first type from being carried by the conveyor into the second tobacco depositing zone and thus to allow, when periodically activated, predetermined amounts of the second type of smoking material to be periodically deposited directly on the belt. The storage means preferably comprises a hopper provided with at least one partition separating said at least two types of smoking material into at least two streams. The means for depositing the types of smoking material is preferably an air entrainment chimney directed upwardly at the underside of the lower run of the belt. The gate means is preferably provided by an air jet directed at the underside of the belt opposed to the side of the belt on which smoking material is to be deposited so as to cancel out the suction effect of the vacuum over the region of the belt at which the jet is directed, and to cancel out the momentum of the smoking material stream created by the belt, thereby to prevent deposition or retention of smoking material on the belt in that region. According to a second aspect of the present invention, there is provided a method of forming a rod of smokeable material from at least two types of smoking material comprising continuously and uninterruptingly depositing first and second types of smoking material onto an air pervious conveyor belt, there being first and second tobacco depositing zones seen in the direction of movement of the conveyor, the second type of smoking material overlying the first type characterised by periodically depositing at preselected times, predetermined amounts of the second type of smoking material directly onto the belt by activating gate means preventing material of the first type from being carried by the conveyor into the adjacent second tobacco depositing zone. The invention will now be described by way of example only with reference to the accompanying diagrammatic drawings in which: Figure 1 is a side view of a portion of a conventional cigarette rod making machine, showing a partitioned hopper, the location of a gate means and a conveyor belt; Figure 2 is a section of the conveyor belt shown in Figure 1 showing a typical configuration of two types of smoking material on the conveyor belt; Figure 3 is a cross-section of a preferred embodiment of a gate means used in conjunction with the conveyor belt of Figure 1; Figure 4 is a detail view of a portion of Figure 3; Figure 5 shows a mechanical gate means; Figure 6 is a section through a completed rod of smokeable material made according to the invention; and Figure 7 shows a cross-section through a cigarette showing a possible configuration of smoking materials according to the invention, together with a graph of the nicotine content along the cigarette. Referring to Figure 1 there is shown in outline a portion of a conventional cigarette making machine, such as the Molins "Mark 8", modified according to the invention. The machine includes a tobacco rod cutting knife and a filter plug assembly mechanism, both of which are well-known and are not illustrated. There is provided a charging hopper 12 adapted to contain separately two different types of tobacco, A and B, by means of a vertical partition 14 dividing the hopper into two compartments. There is provided an air pervious vacuum conveyor belt 16 running in the direction of arrow 18, vacuum being applied to the top surface of the lower run 20 of the belt by a vacuum source. Both types of tobacco are conveyed from the hopper 12 to an upwardly directed air entrainment chimney 22 that is directed at the underside of the lower run 20 of the belt, by a conventional carding conveyor shown diagrammatically at 21, 23 leading from the hopper to the base of the chimney. At the chimney the two types of tobacco A and B are entrained in an air stream and proceed upwardly through the chimney in two parallel streams 24, 26 corresponding to the respective types A and B. The boundary layer between the streams is indicated by chain line 25. The tobacco is held on the underside of the lower run 20 of the belt by virtue of the vacuum applied to the belt from vacuum box 19 and is carried in the direction of arrow 18 to the remainder of the cigarette making machine indicated generally at 28, where it is formed into a rod of tobacco and enclosed in cigarette paper, in a known manner. It will be observed that when the tobacco ascends the chimney and is laid on the belt type A from stream 24 is laid first and is then overlaid by type B from stream 26. A timed gate means is located adjacent the lower run 20 of the belt at a point 30 where the boundary 25 between the streams 24 and 26 meets the lower run 20. The effect of the gate means is to block periodically the carriage of tobacco type A on the belt and to permit type B to be deposited directly onto the belt. A typical configuration of types A and B on the lower run of the belt is shown in Figure 2. A preferred gate means for blocking the carriage of tobacco type A is shown in Figure 3 which shows the belt 16, chimney 22, and an air jet 32 which is directed at an angle to the vertical at the junction of the boundary 25 with the lower run 20 of the belt against the direction of flow of tobacco up the chimney. The effect of the air jet is to neutralise the vacuum on the belt and the momentum of the tobacco at this point and thereby to prevent tobacco type A from passing the gate. Figure 4 shows an enlarged view of the impingement of the jet on the belt. A typical air pressure for the jet will lie in the range 0.7 to 10.5 at. The jet may be actuated by known mechanical or electrical timing devices 37 which will enable the on/off cycle time of the jet to be controlled as required. The position of the jet along the belt may be varied (arrows X-X) to suit the ratio of the tobacco types A and B as determined by the position of the hopper partition. The relative amounts and configurations of types A and B on the belt can thus be easily controlled with minimum waste and degradation of the tobacco. In use it is convenient that the timing means 37 for the jet be linked to the cutting knife and filter plug assembly 39 in the cigarette making machine 28 so that the knife cuts may be made at desired positions along the tobacco rod. Figure 6 shows a typical configuration of tobacco types A and B in a tobacco rod resulting from the invention and further shows typical positions of knife cuts 36. Figure 7 shows an example of a cigarette according to the invention including a conventional filter tip 38. The cigarette contains two tobaccos of differing nature. One type (type A) is a burley tobacco containing 3.43% nicotine and the other (type B) is a flue-cured tobacco containing 0.86% nicotine. The graph immediately above the drawing of the cigarette shows the overall percentage of nicotine along the length of the cigarette. Alternative gate means are possible. In one alternative embodiment shown in Figure 5 the gate means may be provided by a gate 33 acting transversely of the belt 16 in a plane normal to that of the surface of the belt in the region of the boundary 25 between the types of tobacco so as to impede transport of type A along the belt. The gate may be operated by mechanical or electrical means 35.

Claims: 1. Apparatus for forming a rod of smokeable material from at least two types (A, B) of smokeable material, comprising storage means (12) for storing said at least two types (A, B) of smokeable materials, an air pervious conveyor belt (16), a vacuum source (19) located on one side of the belt, tobacco depositing means (22) located on the other side of the belt, said tobacco depositing means comprising a first tobacco depositing zone and _ seen in the direction of movement of the conveyor _ a subsequent second tobacco depositing zone for continuously and uninterruptingly depositing first (A) and second types (B) of smokeable material respectively on the belt so that the second type (B) of smoking material overlies the first type (A), characterised in that the first tobacco depositing zone is arranged adjacent to the second tobacco depositing zone, and in that there are provided gate means to prevent, when activated, smokeable material of the first type (A) from being carried by the conveyor into the second tobacco depositing zone and thus to allow, when periodically activated, predetermined amounts of the second type (B) of smoking material to be periodically deposited directly on the belt. 2. Apparatus as claimed in claim 1 wherein the storage means (12) comprises a hopper provided with at least one partition (14) separating said at least two types (A, B) of smoking material into at least two streams. 3. Apparatus as claimed in claim 1 or 2 wherein the means for depositing the types of smoking material is an air entrainment chimney (22) directed upwardly at the underside of the lower run of the belt (16). 4. Apparatus as claimed in any preceding claim wherein the gate means (32) is provided by an air jet directed at the side of the belt opposed to the side of the belt on which smoking material is deposited so as to cancel out the suction effect of the vacuum over the region (30) of the belt at which the jet is directed, and to cancel out the momentum of the smoking material stream created by the belt, thereby to prevent deposition or retention of smoking material on the belt in that region. 5. Apparatus as claimed in any preceding claim including a timing device (30) to control the operation of the gate means. 6. Apparatus as claimed in claim 5 wherein the timing device is coordinated with the operation of a knife for cutting the rod of smokeable material. 7. Apparatus as claimed in claim 2 wherein the position of said at least one partition (14) is variable thereby to control the ratio of types of smoking material deposited on the belt. 8. Apparatus as claimed in claim 7 wherein the position of the gate means (32) in relation to the belt (16) is variable in accordance with the ratio of tupes of smoking material deposited on the belt. 9. Apparatus as claimed in any one of claims 1 to 3 in which the gate means (32) is provided by a gate (33) acting transversely of the belt (16) in a plane normal to that of the surface of the belt in the region (30) of the boundary between the types of smoking material so as to impede transport of one type of smoking material along the belt. 10. A method of forming a rod of smokeable material from at least two types (A, B) of smoking material comprising continuously and uninterruptingly depositing first (A) and second (B) types of smoking material onto an air pervious conveyor belt (16), there being first and second tobacco depositing zones seen in the direction of movement of the conveyor, the second type (B) of smoking material overlying the first type characterised by periodically depositing at preselected times, predetermined amount of the second type (B) of smoking material directly onto the belt (16) by activating gate means preventing material of the first type (A) from being carried by the conveyor into the adjacent second tobacco depositing zone. 11. A method as claimed in claim 10 wherein the rod is cut at positions (36) determined by the periodic deposition of the second type (B) of smoking material on the belt.

Inventors: CHARD, BRIAN CHESTER
Applicants: IMPERIAL TOBACCO LIMITED
Application year: 1983
Main classification: A24C5
IPC codes: A24C5, A24D1