GB2133270A - Feeding tobacco to cutting machines - Google Patents

Abstract

Apparatus for forming cut tobacco comprises upper and lower conveyors (10, 12) converging towards pressure applying means (14, 16) at their downstream ends, a cutter (20) for cutting tobacco (18) held by the pressure applying means, and a vibrating conveyor (26) with a transversely arched surface for conveying tobacco to the upstream ends of the upper and lower conveyors. In operation, a relatively thin layer of tobacco (28) is formed on the conveyor (26) and is densified by vibration, and is interleaved with adjacent tobacco (30) at the downstream end of the conveyor (26) to form a relatively thick layer of interwoven compacted tobacco which is fed to the cutter. <IMAGE>

Description

SPECIFICATION Feed mechanism for tobacco cutting machines This invention is directed to tobacco cutting machines.

This application is a division of our copending U.K. Patent Application No. 80 39589 filed December 10, 1980.

A known type of tobacco shredding apparatus comprises a rotary carrier for one or more knives which cut tobacco shreds for use in making cigarettes from the leading face of a continuous cake of compacted tobacco. The cake is formed and its contents compacted by a feeding device comprising upper and lower feed conveyors which define a gradually narrowing path extending from a source of threshed tobacco lamina to a comminuting station where the leading face of the cake is squeezed between upper and lower pressure applying elements and moves into the range of the orbiting knives.

Conventionally an automatic feeding system is used to provide the source of tobacco leaves, comprising an upwardly-extending hopper into which the tobacco lamina are dumped. A reciprocally-movable end wall in the hopper opposite to the upstream throat of the conveyors is provided to assist in propelling the tobacco lamina into the throat. Such apparatus is shown in U.S. Patent No. 4,090,521. The tobacco lamina are compressed somewhat by the gravitational force of the head of lamina in the hopper so as to increase the throughput of the shredding apparatus over what otherwise would be the case.

The latter procedure suffers from a number of drawbacks. The tobacco lamina enter the apparatus through a vertically-extending hopper and tend to assume a horizontal orientation. The rear wall movement required to move the lamina into the throat causes the tobacco to move towards a vertical orientation for movement between the compaction conveyors to the cutter.

This effect results in the necessity to apply considerable pressure on the cake of tobacco at the cutter to prevent whole tobacco lamina from being pulled out uncut. The application of this pressure adversely affects the filling power of the tobacco.

The filling power of cut tobacco is its ability to fill a cigarette tube. The greater the filling power, the harder is the cigarette for the same quantity of tobacco. For the economic production of cigarettes, it is desirable for the filling power to be as high as possible. In the prior art procedure noted above, the tobacco tends not to be evenly distributed across the width of the compaction conveyors and, in particular, the tobacco at the sides tends to be less compact than in the middle.

This phenomenon requires the exertion of even greater pressure on the tobacco cake at the cutters in excess of that required in the middle, so that tobacco lamina pull-out at the sides does not occur, thereby further adversely affecting the filling power of the tobacco.

The problem that is solved by the present invention is how to provide the same throughput of tobacco through the tobacco shredding apparatus while at the same time decreasing the pressure requirement at the cutter and thereby improving the filling power of the cut tobacco.

In accordance with the present invention, there is provided a method of supplying tobacco in whole leaf or threshed lamina form to a cutting station wherein the tobacco is forwarded horizontally and is comminuted at the rate at which it enters the station, which comprises forming a relatively thin layer of tobacco adjacent the upper end of an upwardly-inclined conveying surface, the tobacco in the thin layer being oriented substantially in the plane of the thin layer and being substantially uniformly distributed across the width thereof, subjecting the thin layer to vibration whereby the tobacco in the thin layer densifies and is transported down the conveying surface towards the cutting station without the use of any force other than gravity, interleaving the tobacco in the thin layer with longitudinallyadjacent tobacco adjacent the lower end of the conveying surface without substantially altering the orientation of tobacco in the layer to form a relatively thick layer of interwoven compacted tobacco containing the quantity of tobacco desired to be fed to the cutting station, and feeding the relatively thick layer to the cutting station without substantially altering the orientation of the tobacco in the layer.

By forming the tobacco layer with the leaves oriented horizontally, by densifying the tobacco and by avoiding changes in the orientation of the tobacco from formation of the layer to the cutter, substantially all the lamina enter the shredding apparatus in a horizontal orientation and substantially less pressure needs to be applied at the cutter to prevent lamina pull-out, so that the filling power of the tobacco shreds which are formed at the cutter is substantially less adversely affected than in the prior art.

Further by compacting the tobacco layer by the use of gravitational and vibrational forces only, much less compaction is required to be effected using the conveyors in the cutting station, as compared with the hopper-fed system of the prior art, for the same throughput of tobacco. Since less compacting force needs to be applied to the tobacco lamina by the conveyors and such compacting force impairs the filling power of the cut tobacco, the gravity-induced precompaction which is effected in this invention further preserves the filling power of the cut tobacco.

Another factor which is relevant to the filling power of the cut tobacco is the period of time over which physical force is applied to the tobacco, longer periods of time being more detrimental than shorter periods of time. The gravity-induced compacted tobacco is subjected to physical force for a lesser period of time than in the prior art, and this is a source of further filling power preservation.

In the prior art procedure noted above, the head of tobacco in the hopper applies physical force to the lamina in the lower part of the hopper and the tobacco which is forwarded to the cutter is subjected to compression between the conveyor all the way from the mouth to the cutter.

Therefore, not only does the prior art procedure require the application of considerable pressure to the tobacco lamina at the cutter to prevent lamina pull-out as a result of disorientation of the lamina but also considerable physical force is applied to each tobacco lamina for a considerable period of time before it reaches the cutter. The filling power of the tobacco is considerably impaired by the pressure to which the tobacco is subjected.

Transportation of the relatively thin lamina layer to the shredding apparatus is achieved in this invention by the utilization of gravitational forces by orienting the vibrating conveyor at an upwardly acute angle, usually of no more than 450 to the horizontal, generally less than 300.

The angle of the conveyor and the vibration rate applied to the tobacco in the procedure of this invention usually are controlled to prevent the formation of undulations in the layer, since such undulations tend to adversely affect the operation of the shredding apparatus, which requires a uniform thickness of tobacco at the cutter.

In order to overcome the problem of uneven distribution of lamina across the width of the tobacco in the cutter, the surface on which the tobacco layer is formed and transported to the shredding apparatus may be arched transversely thereof.

The provision of the transversely-arched conveyor is novel and, accordingly, the present invention also provides an apparatus for forming cut tobacco, which comprises upper and lower conveyors converging towards a downstream end, pressure applying means at the downstream end for applying pressure to tobacco thereat, cutting means located adjacent the pressure applying means for cutting tobacco held by the pressure applying means, and conveying means for conveying tobacco to the upstream end of said conveyors, the conveying means comprising a vibrating conveyor having a transversely-arched surface.

While the present invention is described herein mainly with reference to threshed tobacco, the principles thereof are equally applicable to whole leaf tobacco.

The invention is described further, by way of illustration, with reference to the accompanying drawings, wherein: Figure 1 is a schematic side elevational view of a tobacco cutting procedure provided in accordance with one embodiment of this invention; and Figure 2 is a sectional view taken on line 2-2 of Figure 1.

Referring to the drawings, upper and lower conveyors 10 and 12 converge towards a downstream throat at which is located a pair of upper and lower pressure plates 14 and 16 mounted to apply pressure to a tobacco cake 1 8 located therebetween. A rotating drum carrier 20 has a plurality of cutting knives 22 peripherally mounted for cutting shreds of tobacco 24 from the cake 18.

The tobacco shreds 24 usually are fed to a conditioning unit (now shown) which changes the moisture content and/or temperature of the shreds, prior to introduction of the conditicned shreds into the distributor of a cigarette-making machine. In a typical plant operation, a plurality of such shredding apparatus is provided.

A vibrating conveyor 26 is provided extending angularly upwardly with respect to the conveyor 10 and tobacco lamina are deposited thereon from a tobacco shower 27 in a thin layer 28 evenly distributed across the conveyor 26 and in which the lamina lie substantially horizontally. The vibrating conveyor 26 precompacts the lamina in the thin layer and, with the assistance of gravity, feeds the tobacco lamina down the slope of the conveyor 26 towards the upstream throat between the conveyors 10 and 12. The angle of the conveyor 26 to the horizontal is selected so that the tobacco lamina in the layer 28 interweave with forwardly-adjacent lamina to build up a thick compacted layer 30 at the upstream throat between the conveyors 10 and 12.The thick layer 30 contains the quantity of lamina desired to pass through the shredding unit and, as a result of the precompacton and interleaving, is of a thickness less than the vertical height of the throat so that the upper surface of the layer 30 engages the upper conveyor 10 part-way into the throat.

The use of a vibrating conveyor 26 arranged at a gentle angle, typcially about 20 to 300, to the conveyor 10 results in the tobacco lamina being oriented horizontally and interwoven one with another to achieve precompaction without the use of external force prior to compaction between the conveyors 10 and 12. It is preferred (as seen from Figure 2) for the vibrating conveyor 26 to be arched along the length thereof in order to compensate for the tendency noted above for uneven distribution of tobacco across the width of the compacting conveyors 10 and 1 2.

Since the tobacco lamina in the tobacco layer 30 are oriented horizontally, are precompacted and are interleaved, much less pressure needs to be applied by the elements 14 and 1 6 to prevent leaf pull-out from the tobacco cake 1 8 than is the case of the prior art system wherein a hopper feed is used for the same throughput of tobacco.

In addition, the use of the arched conveyor surface on the vibrating conveyor 26 provides a more even distribution of tobacco across the width of the tobacco cake 1 8 than is the case of the prior art and this contributes further to the decreased pressure requirement. It has been found that the pressure requirement can be decreased to less than half that conventionally used with the prior art hopper-feed apparatus.

The ability to operate with less compression of the tobacco in the tobacco cake 1 8 at the cutter 20 and the application of compression forces by the conveyors 10 and 1 2 for a shorter period of time as a result of precompaction and proper lamina orientation in accordance with this invention result in a much decreased impairment of the filling power of the tobacco shreds 24 when subsequently used in cigarette manufacture, leading to greater economy of tobacco use, as compared with prior art procedures.

A more consistent width of cut of tobacco from piece to piece is attained using the procedure of this invention, so that the quality of the tobacco shreds producad is improved with respect to those produced by the prior art procedure.

In addition, the infeed flow rate may be varied, in which event the physical height of the tobacco cake 1 8 varies. This throughput variation depends only on the flow input to the cutter, rather than by the use of compression as in the prior art. A very short start up period is required with the procedure of this invention.

In summary of this disclosure, the present invention provides a novel method of feeding tobacco lamina to a tobacco cutting machine to result in improved filling power of the tobacco shreds, when compared with the prior art.

Claims (9)

1. A method of supplying tobacco in whole leaf or threshed lamina form to a cutting station wherein the tobacco is forwarded horizontally and is comminuted at the rate at which it enters the station, which comprises forming a relatively thin layer of tobacco adjacent the upper end of an upwardly-inclined conveying surface, the tobacco in the thin layer being oriented substantially in the plane of the thin layer and being substantially uniformly distributed across the width thereof, subjecting the thin layer to vibration whereby the tobacco in the thin layer densifies and is transported down the conveying surface toward the cutting station without the use of any force other than gravity, interleaving the tobacco in the thin layer with longitudinally-adjacent tobacco adjacent the lower end of the conveying surface without substantially altering the orientation of tobacco in the layer to form a relatively thick layer of interwoven compacted tobacco containing the quantity of tobacco desired to be fed to the cutting station, and feeding the relatively thick layer to the cutting station without substantially altering the orientation of the tobacco in the layer.

2. A method as claimed in claim 1, in which the speed and force of conveying of the relatively thin layer is maintained less than that which causes mounds of tobacco to form.

3. A method as claimed in claim 1 or 2, in which the relatively thin layer is formed from a downwardly-flowing shower of tobacco.

4. A method as claimed in claim 3, in which the tobacco shower is distributed over a portion of the longitudinal dimension of the conveying surface.

5. A method as claimed in any one of claims 1 to 4, in which the conveying surface is upwardly inclined at an angle of no more than 45" to the horizontal.

6. A method as claimed in claim 5, in which the angle is from 200 to 300 to the horizontal.

7. A method of forming cut tobacco substantially as hereinbefore described with reference to, and as illustrated in, Figures 1 and 2 of the accompanying drawings.

8. A method of forming cut tobacco substantially as hereinbefore described with reference to, and as illustrated in, Figures 1 and 2 of the accompanying drawings.

8. An apparatus for forming cut tobacco, which comprises upper and lower conveyors converging towards a downstream end, pressure applying means at the downstream end for applying pressure to tobacco thereat, cutting means located adjacent the pressure applying means for cutting tobacco held by the pressure applying means, and conveying means for conveying tobacco to the upstream end of said conveyors, the conveying means comprising a vibrating conveyor having a transversely-arched surface.

9. An apparatus as claimed in claim 8, in which the vibrating conveyor is oriented angularly upwardly from the upstream end of the conveyors.

1 0. An apparatus for forming cut tobacco substantially as hereinbefore described with reference to, and as illustrated in, Figures 1 and 2 of the accompanying drawings.

New claims or amendments to claims filed on

9.3.84 Superseded claims 1-10 New or amended claims:

1. A method of supplying tobacco in whole leaf or threshed lamina form to a cutting station wherein the tobacco is forwarded generally horizontally and is comminuted at the rate at which it enters the station, which comprises forming a relatively thin layer of interleaved tobacco adjacent the upper end of an inclined conveying surface, the tobacco in the thin layer being oriented substantially in the plane of the thin layer and being substantially uniformly distributed across the width thereof, subjecting the thin layer to vibration whereby the tobacco in the thin layer densifies and is transported down the conveying surface toward the cutting station without the use of any force other than gravity, interleaving the tobacco in the thin layer with longitudinallyadjacent tobacco adjacent the lower end of the conveying surface without substantially altering the relative orientation of tobacco in the layer to form a relatively thick layer of interwoven compacted tobacco containing the quantity of tobacco desired to be fed to the cutting station, and feeding the relatively thick layer in a generally horizontal direction to the cutting station without substantially altering the relative orientation of the tobacco in the layer.

2. A method as claimed in claim 1, in which the speed and force of conveying of the relatively thin layer is maintained less than that which causes mounds of tobacco to form.

3. A method as claimed in claim 1 or 2, in which the relatively thin layer is formed from a downwardly-flowing shower of tobacco.

4. A method as claimed in claim 3, in which the tobacco shower is distributed over a portion of the longitudinal dimension of the conveying surface.

5. A method as claimed in any one of claims 1 to 4, in which the conveying surface is upwardly inclined at an angle of no more than 450 to the horizontal.

6. A method as claimed in claim 5, in which the angle is from 200 to 300 to the horizontal.

7. A method as claimed in any one of claims 1 to 6, in which the vibration includes a component of vibration generally normal to the plane of the thin layer.