|Publication number||US3386451 A|
|Publication date||Jun 4, 1968|
|Filing date||Dec 21, 1965|
|Priority date||Dec 21, 1965|
|Publication number||US 3386451 A, US 3386451A, US-A-3386451, US3386451 A, US3386451A|
|Inventors||Andre Pietrucci, Georg Schrep|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (6), Referenced by (4), Classifications (7)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Filed Dec. 21, 1965 June 1963 A. PIETRUCCI ET AL 3,386,451
APPARATUS FOR TREATING FOLIATE MATERIAL SUCH AS TOBACCO I 4 Sheets-Sheet l JNVENTORS ANDRE PIE TRUC C! AND GEO/'76 SCHREP June 4, 1968 A. PIETRUCCI ET AL 3,386,451
APPARATUS FOR TREATING FOLIATE MATERIAL SUCH AS TOBACCO Filed Dec. 21, 1965 4 Sheets-Sheet 2 INVENTORS ANDRE P/ETRUC'C/ AND GEORG SCHREP June 4, 1968 A. PIETRUCCI E 3,386,451
APPARATUS FOR TREATING FOLIATE MATERIAL SUCH AS TOBACCO Filed Dec. 21, 1965 4 Sheets-Sheet 5 INVENTORS ANDRE PIE TRUC Cl AND GEORG SCH/7E P June 4, 1968 A. PIETRUCCI ET AL 3,386,451
APPARATUS FOR TREATING FOLIATE MATERIAL SUCH AS TOBACCO Filed Dec. 21, 1965 4 Sheets-Sheet 4 INVENTORS ANDRE P/ETRUCC/ AND GEORG SCHRE P United States Patent 3,386,451 APPARATUS FOR TREATING FOLIATE MATERIAL SUCH AS TOBACCO Andre Pietrucci, Fleury-les-Aubrais, France, and Georg Schrep, Hamburg, Germany, assignors to Service dExploitation Industrielle des Tabacs et des Allumettes, Paris, France, a French public establishment Filed Dec. 21, 1965, Ser. No. 524,671 14 Claims. (Cl. 131146) ABSTRACT OF THE DISCLOSURE Apparatus for stripping and separating tobacco comprises several coaxial stripping devices each having a cage and a drum bounding a stripping chamber. The cage and/or the drum of each stripping device is rotatable and the stripping chambers are concentric, each of these chambers being bounded by at least one rotary wall. The stripping devices are surrounded by a casing which is associated with a feed device for tobacco and communicates with a takeofi duct for stripped material.
The present invention relates to apparatus for treating foliate material such as tobacco, and is particularly concerned with apparatus for stripping and separating tobacco or other foliate material which comprises a plurality of stripping devices of different diameters having stripping drums rotating about vertical axes and stripping cages associated with them.
The co-axial arrangement of the stripping devices of different diameters is to ensure that material before being stripped further passes directly from a smaller stripping device into a larger stripping device.
For this purpose it is known to arrange a plurality of stripping devices of different diameters one above the other with the stripping drum axes in such manner that the stripping device with the smallest diameter is the uppermost stripping device and that the subsequent lower stripping devices have increasingly larger diameters. The mixed material issuing from an upper stripping device is projected into a portion of a separating duct in which mixed material which has already been separated is conveyed upwardly. A suitable construction of this separating duct enables a good separation effect to be obtained with this type of construction.
An object of the invention is to provide apparatus of the kind referred to above in which the streams of partially or totally stripped material and of different compositions are prevented entirely or at least to a considerable extent from intermixing or crossing each other.
For this purpose the invention provides that the stripping devices are mounted inside each other, that is to say, their stripping chambers are concentric and comprise at least one rotary wall which may be continuous or discontinuous and which is provided with teeth, wherein at least one of these chambers is constituted by two concentric walls one of which rotates and wherein the stripping devices are arranged in a casing which is connected at the one end to a feed device for foliate material and at the other end to a take-ofi duct for the leaf material obtained.
A particular embodiment of the invention provides a free space between the stripping cage of one stripping device and the stripper drum of the adjacent larger stripping device, the free space constituting a separating duct.
Due to the fact that the material is supplied to the first stripping device usually only over a small portion of the periphery of the device and because of the nature of the stripping operation, the stripped material is not ejected 3,386,451 Patented'June 4, 1968 from the stripper cage in a regular manner. The charging of the circular or partially circular separating ducts thus varies from one circular section to the next. Since the flow speed is a function of the charge of the separating ducts, undesirable transverse currents occur in the separating ducts. In order to avoid this, provision is made in one embodiment of the apparatus according to the invention that at least one of the separating ducts is divided by partition walls which extend parallel to the general flow direction of the separating air. The heavy particles carried upwardly in the separating ducts are separated a second time owing to the fact that the separating ducts terminate in a common main duct and are con nected through this duct to a common suction duct which conveys away only stripped leaf material.
In such apparatus the outer stripping device has the largest diameter. In order to utilise fully the maximum output of this highly eflicient stripping device the feed of material to be stripped can be associated with the outer stripping device. The dimensions of the openings in the stripping case and the distances between the beater teeth are advantageously larger in this outer stripping device than the corresponding dimensions of the stripping devices with smaller diameters, in order to obtain in the first stage of tobacco leaf stripping leaf portions as large as possible. The mixture which must be subjected to further stripping must be guided to a subsequent interior stripping device by passing through as large a portion as possible of the periphery of the stripper drum. This operation must be effected by means of a recycling device for the mixture disposed above the stripping devices and guiding the mixture from the separating chamber of an outer stripping device towards an inner stripping device. The separating duct of the inner stripping device is advantageously of circular shape so that the stripped mixture can be ejected from the whole periphery of the stripper cage.
The preferred feed to the largest exterior stripping device permits the stripping devices to be dimensioned favourably in respect of the required throughput of material; in fact this throughput decreases dependently upon the decrease of the diameters of the stripping devices. The whole periphery of each stripping device is surrounded by a distinct separating duct. The separating process in these ducts which is effected in the region of the stripping devices and which must remove the major portion of the ribs is not afiected by material which is carried upwardly and transversely with respect to the ejected material. The separating process in the common duct takes place without being affected by the stripping devices.
In another embodiment the outer wall of one of the stripping devices is the inner Wall of the next following stripping device, and the radially extending teeth can be fixed on the inner or outer surfaces of these walls or on both of them simultaneously. This is the case when the central stripping device comprises a rotary drum provided with teeth turning in a rotary casing having teeth on its outer surface. This is also the case when the drum of the central stripping device rotates in a stationary casing which constitutes the inner wall of the next following stripping device in which rotate the teeth which are mounted internally on its outer casing. This is also the case when the central stripping device is constituted by a single exterior rotary casing on which are attached teeth sweeping the chamber of the stripping device and teeth sweeping the chamber of the next following stn'pping device.
The various combinations may be utilised in accordance with requirements.
The casing of the apparatus may be merged in respect of the outer stripping device with the outer wall of the device. This wall may be stationary.
The direction of rotation of successive rotary walls may be in the same sense or in the opposite sense.
The invention provides feeder means for the foliate material constituted by one or more conveyance ducts for foliate material which terminate in the annular space enclosed between the extensions of the walls of the stripping device or stripping devices to be fed. The duct or ducts may be pneumatic conveyance ducts, and the air current may traverse the stripping device or stripping devices to be fed from the bottom to the top.
The duct or ducts may terminate tangentially in the annular space to be fed and the rotation of the air may be the same as or opposite to the direction of rotation of the teeth in the stripping device or devices to be fed.
In a modification of the invention the foliate material to be stripped is delivered into the annular space through one or more rotary lock gates the blades of which sweep preferably at least a portion of the annular space to be fed.
The foliate material delivered into the space is carried across the stripping chamber under the action of an air current which may be rising and directed towards the base of the chamber.
The embodiment may comprise one separation chamber arranged in the whole or nearly the whole annular space above the top of a stripping device traversed from the bottom to the top and of one or more adjacent stripping devices, said separating chamber being provided in order to permit the light particles to be carried upwardly and the heavier particles to be guided by gravity towards the adjacent stripping device or devices.
For this purpose there may be provided one or more resilient inflatable cushions, for example of annular shape, for adjusting the volume or the configuration of the separating chamber.
The embodiment may also comprise a separating chamber arranged in the whole or nearly the whole annular space between the bottom of a stripping device traversed from the top to the bottom by the flow of particles and of an adjacent stripping device or stripping devices traversed by a rising air current, said separating chamber being provided in order to permit the ribs to drop by gravity and the particles which still include rib material to be carried towards the stripping device or devices through which the rising air current travels.
The rising air current may be independent of the current which feeds one of the other stripping devices. It may be obtained by division from the general air stream supplying a plurality of stripping devices.
In the embodiment of the invention the bases of successive stripping devices may be situated in the same plane or in adjacent planes.
A rising air current may be caused to circulate in a stripping device fed from above with material to be stripped, the air current being adjusted so that it carries away only particles of leaf material which have been stripped in the course of the downward travel.
Direct lateral ejection of products stripped in a stripping device towards a stripping device of larger diameter may be obtained by completely or almost completely closing the bottom of the stripping device with the smaller diameter and by providing openings or perforations in the intermediate wall between the two stripping devices. The dimensions of the openings or perforations of successive non-continuous partition walls are determined in proportion to the dimensions of the products to be ejected laterally.
In one embodiment of the invention there may be provided a final stripping device arranged co-axially with the embodiment, having a solid bottom, an external wall with apertures communicating with the atmosphere, and located under at least one of the stripping devices.
The top of the final stripping device may communicate with the separating chamber provided under the assembly of the other stripping devices.
The wall provided with the apertures or the rotary wall provided with teeth of the finishing device, or both may be integral with a wall or walls of the assembly of the other stripping devices.
There may be provided a control mechanism by means of which the various stripping devices can be run at different speeds.
One of the advantages of the invention is the small constructional height of the apparatus.
Various embodiments of the invention will be described below by way of example with reference to the ac companying drawings, in which:
FIG. 1 illustrates apparatus with two concentric stripping devices separated by a separation duct, in section along the line II of FIG. 2;
FIG. 2 illustrates a section along the line II-II of FIG. 1;
FIG. 3 illustrates partially in section, apparatus according to the invention comprising two concentric and adjacent stripping devices and on the same axis, in the lower portion, a stripping device comprising a final beater device;
FIG. 4 illustrates in section a modification of the apparatus shown in FIG. 1 with a different feed arrangement for the foliate material and a different position of the final beater device, and
FIG. 5 illustrates in section apparatus comprising three co-axial and adjacent stripping devices.
In the example illustrated in FIGS. 1 and 2 the apparatus comprises an outer casing or housing 2 and two concentric stripping devices 4 and 21. The outer stripping device 4 is of circular shape with a rotary stripper drum 6 around which is mounted a stripper cage 8 in a stationary position. The latter is supported from above by means of a support 10 in the form of a plate fixed to the casing 2. A certain number of guide wheels 12 are mounted idly on the periphery of the stripper cage 8; the peripheral ridge of these guide wheels engages the groove of a ring 14. The stripper drum 6 which is fixed at its bottom to this ring 14 is guided by the guide wheels 12 in a horizontal plane of rotation and is caused to rotate by a friction wheel 16. This wheel 16 is mounted on a bearing 18 and is engaged by a motor (not shown) by means of a V-belt 20. The inner stripping device 21 is supported at the top of its vertical shaft 22 in the support 10 by a head bearing 24 which prevents any axial displacement, and at the bottom by a bearing 26, and is set into rotary motion by means of a V-belt 28 passing over a belt pulley 30. In the stripping device 21 a stripper drum 32 rotates in the interior of a stripper cage 34.
The casing 2 includes three main separating ducts 36, 38, 40 two of which are illustrated in FIG. 1. These ducts terminate in corresponding separating ducts 42, 43 and 45 (FIG. 2) arranged in zones around the major portion of the stripping device 4. Between the stripping devices 4 and 21, a wall 46 is fixed to the support 10 which delimits or delineates the separating ducts 50, 55 and 57 between the stripper cage 34 and the stripping device 4. These separatmg ducts are connected to the main duct-s 36, 38, 4G by means of three openings 52 two of which are visible in FIG. 1, their corresponding ducts 54 and further openings 56 being provided in a cap 48. In FIG. 1 ducts 54 are shown for the main ducts 36 and 38. The cross-section of the main ducts increases continuously from the bottom to the top. A wall 58 starting at the peak of the cap 48 which extends over all the stripping devices separates all the main ducts 36, 38, 40 which terminate in their upper zone in a common exhaust duct 60 which is connected to a fan (not shown in the drawings). On the right-hand side of FIGS. 1 and 2 a chute 62 which is open towards the top and which serves for feeding material to be stripped is mounted on the upper portion of the stripping device 4 in a free space between the ducts 36 and 40.
Under the casing 2 a take-off conveyor 64 rotates around a driving roller 66. A cap 68 fixed by webs 70, 72 to the bearing 26 covers the belt pulley 30 and a portion of the V-belt 28.
Caps over the rotary members 12, 14, 16 of the stripping device have not been illustrated in the drawing for reasons of clarity.
The method of operation of the apparatus is as follows:
A fan (not shown on the drawings) :produces an air stream in the take-off pipe 60, in the main separating ducts 36, 38, 40 and in the ducts 42, 43, 45 and 50, 55, 57. This air stream circulates around the stripping cages 8 and 34 vertically with reference to the plane of rotation. When the material to be stripped is fed through the chute 62 to the rotary stripping device 4 this material is stripped and radially ejected across'the stripper cage 8 into the rising air stream; it undergoes there by a first separation in the ducts 42, 43, 45 in such manner that the ribs from which the leaf material has been removed drop by gravity in counterfiow to the rising air stream on to the take-off conveyor 64. The leaf material or the light mixture is carried away upwardly by the air stream and guided to the main separating ducts 36, 38, 40. In order to explain the sequence of the operation reference is made below only to the main duct 38 located on the left-hand side in FIG. 1. In the cross-section of this main duct the travelling speed of the rising air stream decreases sufliciently for the light leaf material to be carried away in the direction of the arrow towards the top as far as the take-off pipe 60, whereas the mixture comprising ribs without leaf material, ribs with leaf material and leaf material without ribs is displaced towards the right, that is to say, towards the inclined wall of the cap 48, and drops under the action of gravity or in the present case under the action of suction, into the inner stripping device 21. This dropping is effected across the openings 51, 53 in the direction of the broken arrows and entry into the stripping device 21 takes place from above.
In this stripping device the mixture is stripped again. The ribs which are definitely separated from the residual leaf material and the leaf material without ribs pass radially across the stripper cage 34 and enter into the rising air stream in the ducts 50. The ribs fall into the take-off conveyor 64, and the light leaf material is carried away through the duct 54 to the main duct 38. All streams of leaf material issuing from the ducts 42, 50 are joined in the main duct 38 and are guided through the take-01f pipe 60 to a further manipulation process. In the enlarged cross-section of the main duct 38 there meet at the same time all other streams of the mixture which return to the stripping device 21 through openings 51, 53 and this occurs at a variable return frequency until the whole of the mixture is substantially completely freed of ribs and all portions which are constituted only by leaf material have been removed. The leaf material of the main ducts 36, 40 and the corresponding ducts 55, '57 and 43, 45 are treated in the same manner as described for the separating ducts 38.
In this process the external stripping device 4 is rotated by means of the V-belt 20 through the friction force of the guide wheel 16, and the stripping device 21 is set into rotary motion by the V belt 28 and the belt pulley 30. The rotary speeds of the stripping devices 4 and 21 are such that the speed of each stripping device permits the most favourable stripping action to be obtained; thus these two speeds may be different. These different speeds can be controlled by means of an infinitely variable change speed device which is not shown in the drawings.
The flow speed of the air stream in the separating ducts and in all the main ducts must also be controllable. This control is effected by means of dampers or valves, not shown in the drawings, which may be arranged either directly on the fan, which is not shown in the drawings, or
at any other appropriate point in the take-off pipe 60 or at any other point of the system.
The embodiment shown in FIGS. 1 and 2 constitutes a practical example for a separating system, but which is not necessarily used in order to carry out the process. The various main ducts and the separating ducts may alternatively be constructed and arranged in a different appropriate manner within the scope of the invention. The invention provides also for the use of for example three or more stripping devices instead of two inserted one into the other in the manner illustrated in FIG. 1. The whole system will then comprise an inner stripping device 21 surrounded by one or more circular stripping devices actuated in the same direction or in opposite directions at equal or diiferent rotational speeds. The stripping devices may alternatively be arranged at different levels and they may have different constructional heights. Furthermore it is of little importance that the control of the stripping devices is different from the control i1lustrated in FIG. 1. The friction wheels 16 may for example be replaced by gear wheels and the circular stripping device 4 may be arranged in a difierent but appropriate manner, for example on a rotary shaft.
Similarly the arrangement of the chute 62 serving for feeding material to be stripped has been illustrated only by way of example. The feed may alternatively be efiected by means of other systems, such as conveyor belts, or a lateral pneumatic duct, or by using other auxiliary elements operative either from above or in a circular manner. More than one feed point may be provided or other feed points may be selected. Similarly the passage of the mixture from the outer stripping device towards the inner stripping device may alternatively be effected in a different manner. Moreover the connection and removal of the ribs may be effected for example by a pneumatic duct.
In the example illustrated in FIG. 3 the apparatus comprises a shaft 101 held vertically by two fixed bearings 102, 103 and is actuated through a pulley 104 by means of a motor and a power transmission not shown. A core member 105 which is fixed on this shaft embodies on its external wall teeth 106 and rotates in the interior of a cage constituted by bars 107. A second core member 108 guided by the shaft 101 is actuated by means of a pulley 109. In its lower portion this core member comprises teeth 110 which are arranged radially and which rotate in the interior of a stationary cage constituted by bars 111. The upper portion of the core member 108 supports the cage which is constituted by the bars 107 and which rotates at the same speed as the core 108. Bars 107 are provided with radial teeth 112 arranged so that they enter between counter teeth 113 fixed to the casing 114.
From this description it will now be possible to follow the functioning of the embodiment:
The tobacco leaves or similar foliate material are introduced into the casing 114 by means of a rotary bladed lock gate 115. Under the action of the air stream which rises at great speed and which penetrates across the openings 116 between the bars 111 and which is caused by the section of a fan (not shown) connected to a take-off pipe or tube 117, these leaves are carried away upwardly and during the passage through the action zone of the teeth 112 and counter teeth 113 they are subjected to shocks which cause the leaf material to be detached from the ribs.
The whole of the product obtained which is constituted of pieces of leaf material without ribs, pieces of leaf material to which ribs are still attached and some ribs nearly completely cleaned, is carried away by the air current into the retarding chamber 118 wherein, since the cross-section offered to the passage of the air is increased, a considerable slowing down of the air speed is produced. Under the effect of this slowing down the heavier particles, that is to say the pieces containing ribs, cease to rise and fall down into the stripping device constituted by the core member and the bars 107. In contrast the light particles 7 continue to rise in the chamber 118 and are removed through the pipe 117.
The heavier particles enter the inner stripping device and are subjected there to a renewed stripping process at the end of which the stripped products are ejected across the bars 107 and rejoin the flow of tobacco which traverses the outer stripping device. Together with the latter they are separated again in the chamber 118 at the end of which the pure leaf material Will be removed through the pipe 117 whereas the heavier particles fall back into the inner stripping device. Thus there is produced a permanent action in the course of which each piece of leaf material which is still attached to a rib circulates between the outer stripping device and the inner stripping device and vice versa until the rib is Completely cleaned.
When a rib is almost completely cleaned its high density and its small carrying surface are such as to permit it to drop between the teeth 106 of the interior stripping device and to escape from it through the base thereof. It thus arrives in the final beater or stripping device constituted The ribs ejected from the apparatus are collected by a rotating conveyor 119 which may be of the shaker type.
In order to facilitate the control of the air speed and thus the separation in the chamber 118 there may be disposed in this chamber a member permitting the cross-section of the passage of the air to be varied. In the example described this member is constituted by a resilient cushion 120 which is connected to a compressed air source and which is fixed to the cylindrical wall 121. By varying the quantity of air contained in the cushion its thickness can be varied and thus also its external diameter.
In the example described the feed of leaf material is elfected by a single lock gate 115. The embodiment may be fed alternatively by means of two or more gates distributed over the periphery of the casing 114.
Similarly, only a single suction pipe 117 has been illustrated. In fact a plurality may be used connected either to the same fan or to different fans, in order to obtain a better uniformity of distribution of the air current.
In the same way the chamber 118 may be closed partly or completely by means of radial closure members 122 thus reducing in the separation zone the effect of centrifugal forces due to the rotation of the beaters.
The embodiment illustrated in FIG. 4 differs from the preceding one only by the position of the final beater or stripping device, the method of feeding leaf material and the circulation of the air current.
According to this modification the lower portion of the casing 114 has an annular body member into which .terminates tangentially an air inlet tube 123. The air travels thus in the casing 114 along a helical path. The foliate material to be stripped is introduced into the tube 123 at a point not illustrated. Once the material is in the casing 114 it rises therein turning over at the same time and reaches the outer stripping device the mobile teeth of which rotate preferably in the same direction as the air current. Thereafter successive beating and separating is efiected as indicated above, until the ribs are almost completely cleaned.
The almost completely cleaned ribs are discharged slowly into the inner stripping device and finally fall into the lower portion of this device where the final stripping device is located which is constituted by the teeth 110 and the bars 111. When the air path is arranged so that the quantity of air admitted into the pipe 123 is smaller than the quantity which leaves through the pipe 117, air
8 enters through the openings 116 between the bars 111. This air cannot prevent the ejection of the ribs; in fact it prevents the removal of the small particles of leaf material which have been freed in the final stripping device and which will be carried away towards the duct 117 across the stripping devices.
FIG. 5 illustrates a second modification of the apparatus and comprises three co-axial stripping devices. The foliate material to be stripped enters into the apparatus through the tube 123 which terminates tangentially in the annular space 124 which acts in the same way as a cyclone. The outlet opening of this cyclone communicates directly with a first stripping device constituted on the one hand by teeth 106 fixed to the core member actuated by the pulley 109, and on the other hand by a cage formed by the bars 107. This cage is fixed to the core member 125 which is attached to the shaft 101. It rotates at the same speed as this shaft.
The foliate material admitted into this first stripping device is subjected to a first stripping action at the end of which the freed products are removed partly by lateral ejection across the bar cage 107 and partly through openings provided in the top of the cage. The tobacco particles which arrive in the retarding chamber 118 are separated there into particles of pure leaf material which are removed from the apparatus through the pipe 117, and into ribs and particles of leaf material to which ribs are still attached which fall back by gravity into the second and third stripping devices.
In principle the construction of the second stripping device is not substantially different from that of the first device. It comprises teeth 126 fixed on bars 107 and bars 127 connected to an annular member 128 actuated by one or more friction wheels 129. The particles freed in the second stripping devices are ejected laterally across the cage formed by the bars 127 and enter into the third stripping device, constituted by the teeth 112 fixed to the bars 127, and counter teeth 113 fixed to the casing 114.
At the level of the lowermost teeth 112 the casing 114 comprises relatively small apertures limited by .the bars 111 in such manner that the final cleaning of the ribs is ensured. The air entering through these apertures ensures that the light particles freed in the finishing zone and in the third chamber are carried away towards the chamber 118.
It will be seen that the supply of leaf material may be efiected as indicated in the embodiment illustrated in FIG. 3. In this case the annular space 124 is open to the atmosphere and the foliate material must be applied in the vicinity of its inlet region by a conveyor. In order to ensure a better distribution of the tobacco supplied there may be utilised moreover two or more conveyors delivering foliate material to points distributed over the periphcry of the inlet region of the space 124.
Normally an embodiment such as described with reference to the various modifications illustrated in FIGS. 3, 4 and 5 is sufficient to ensure complete stripping of the tobacco introduced. However, when very long or very light tobacco is treated, or when operation takes place at a high rate of throughput, accumulations of ribs and leaf material are formed in the chamber 118 which fall back into the chambers causing an objectionable degradation of the leaf material. In order to avoid this disadvantage the throughput of separating air can be regulated in such manner that these accumulations cannot form. It may also be found that products which contain ribs are carried away with the particles of pure leaf material; these products are largely complete or almost complete leaves. It is then sutficient to arrange between the pipe 117 and the apparatus or device intended to receive pure leaf material, one or more separating chambers of a classic type in which the particles of leaf material which still comprise ribs are separated from the pure leaf material, in order to be reintroduced into the flow of foliate material admitted to the apparatus for the first time.
In any embodiment the stripping effect in one of the stripping devices is a function of the relative speed existing between the two casings limiting the stripping device in question. This relative speed can be obtained either by causing the two casings to rotate in opposite directions or by causing them to rotate at the same time but at different speeds or even by causing them to rotate as a unit. The choice between these various embodiments depends on the type of tobacco to be stripped and on .the degree of stripping which must be obtained.
What we claim is:
1. An apparatus for stripping and separating tobacco or other foliate material comprising a plurality of coaxial stripping devices each having a stripper cage anda stripper drum delineating a stripping chamber, said chambers being concentric and at least one of said cage and said drum being a rotary member and at least one of such chambers being delineated by concentric walls of which at least one is rotary, a casing surrounding said stripping devices, a feed device for foliate material and a take-off duct for the leaf material obtained communicating with said casing.
2. Apparatus according to claim 1, wherein a free space is provided between the stripper cage of one stripping device and the stripper drum of the adjacent larger stripping device, said space being arranged to constitute a separating duct.
3. Apparatus according to claim 2, wherein partition walls extending parallel to the main direction of flow of the separating air devide at least one of the separating ducts.
4. Apparatus according to claim 2 further comprising a common take-off duct and a common main duct connecting said separating ducts with said take-01f duct.
5. Apparatus according to claim 1 wherein said feed device for foliate material is associated with the external stripping device.
6. Apparatus according to claim 2 further comprising means located above said stripping devices for recycling mixture from a separating duct of an interior stripping device towards an interior stripping device.
7. Apparatus according to claim 1 wherein the exterior delineating wall of a stripping device is the interior delineating Wall of the next following stripping device.
8. Apparatus according to claim 7 wherein the central stripping device comprises a rotary drum provided with teeth turning in a cage provided with teeth at least on its exterior surface.
9. Apparatus according to claim 7 wherein the walls delineating the stripping chamber of at least one of said stripping device are provided with extensions delineating an annular space and at least one conveying duct for feeding foliate material terminate on said annular space.
10. Apparatus according to claim 7 further comprising means for creating a rising air current for carrying away the discharged foliate material.
11. Apparatus according to claim 7 further comprising an annular separation chamber above at least one of said stripping devices thereby permitting light particles to be carried upwardly and heavier particles to drop by gravity towards at least one adjacent stripping device.
12. Apparatus according to claim 11 further comprising at least one inflatable resilient cushion in said separating chamber for adjusting the volume thereof.
13. Apparatus according to claim '16 further comprising an annular separating chamber below at least one .of said stripping devices thereby permitting ribs to drop by gravity and particles of leaf material to be carried away towards the stripping device or devices traversed by the rising air current.
14. Apparatus according to claim 7 further comprising a final stripping device coaxial with said apparatus, and having .a solid bottom, and an external wall provided with apertures communicating with the atmosphere, and located under at least one of said stripping devices.
References Cited UNITED STATES PATENTS 1,024,832 4/1912 Cox 24151 1,977,771 10/1934 McMahan 131l46 X 2,050,765 8/1936 Rundell 131146 X 2,474,314 6/1949 Koehne 241-51 X 3,046,998 7/1962 Mortimer 131l46 3,229,698 1/1966 Johansson et al. 131- 146 ALDRICH iF. ME'DBERY, Primary Examiner.
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|U.S. Classification||131/312, 209/133, 131/110|
|International Classification||A24B5/10, A24B5/00|