US3844295A

US3844295A - Method and apparatus for forming a tobacco stream

Info

Publication number: US3844295A
Application number: US00267709A
Authority: US
Inventors: H David
Original assignee: Hauni Werke Koerber and Co KG
Current assignee: Koerber AG
Priority date: 1971-07-06
Filing date: 1972-06-29
Publication date: 1974-10-29
Anticipated expiration: 1991-10-29
Also published as: DE2225596A1; FR2145177A5

Abstract

A distibutor for shredded tobacco wherein a carded belt or drum withdraws a wide layer of tobacco shreds directly from a magazine and advances successive increments of the layer into the range of bristles on a rapidly revolving brush serving to propel the shreds of successive increments onto a spaced-apart portion of the belt or drum to form thereon a relatively small floating supply of loose shreds. The belt or drum removes from the floating supply a wide sliver of loose shreds which is thereupon showered and converted into a narrow tobacco stream. The quantity of shreds in the floating supply is monitored by a detector which regulates the position of a refuser cooperating with the belt or drum immediately downstream of the magazine to control the height of the layer thereon.

Description

ilnited States Patent 1191 David 1 Get. 29, 1974 [54] METHOD AND APPARATUS FOR FORMING 668,641 10/1964 Italy 131 109 R 822,108 10/1959 Great Britain 131/21 A A TOBACCO STREAM [75] Inventor: Harry David, Hamburg, Germany [73] Assignee: I-Iauni-Werke, Korber & Co. KG,

Hamburg, Germany [22] Filed: June 29, 1972 [21] Appl. No.: 267,709

[30] Foreign Application Priority Data July 6, 1971 Great Britain 31639/71 [52] U.S. Cl. 131/21 A, 131/84 B, 131/109 R, 131/110 [51] Int. Cl. A24c 05/39 [58] Field of Search 131/21, 21 A, 21 B, 84, 131/84 B, 84 C, 108, 109, 110

[56] References Cited UNITED STATES PATENTS 550,101 11/1895 Flanegin 131/109RUX 2,149,925 3/1939 Molins 131/109 AB 2,827,058 3/1958 Bogaty 2,861,683 11/1958 Gilman 131/21 B 3,316,917 5/1967 Richter l3l/84C FOREIGN PATENTS OR APPLICATIONS 594,217 5/1959 Italy 131/84 B Primary ExaminerJoseph S. Reich Attorney, Agent, or Firm-Michael S. Striker [57] ABSTRACT A distributor for shredded tobacco wherein a carded belt or drum withdraws a wide layer of tobacco shreds directly from a magazine and advances successive increments of the layer into the range of bristles on a rapidly revolving brush serving to propel the shreds of successive increments onto a spaced-apart portion of the belt or drum to form thereon a relatively small floating supply of loose shreds. The belt or drum removes from the floating supply a wide sliver of loose shreds which is thereupon showered and converted into a narrow tobacco stream. The quantity of shreds in the floating supply is monitored by a detector which regulates the position of a refuser cooperating with the belt or drum immediately downstream of the magazine to control the height of the layer thereon.

13 Claims, 3 Drawing Figures PAIENIEBUBIZQ am:

am aor s $844295 METHOD AND APPARATUS FOR FORMING A TOBACCO STREAM BACKGROUND OF THE INVENTION This invention relates to a method and apparatus for forming a stream of fibrous material, and more particularly to an improved method and apparatus for forming a stream of comminuted tobacco leaves or comminuted reconstituted tobacco. Still more particularly, the invention relates to improvements in a method and apparatus for forming a homogeneous stream of discrete fibrous particles which can be converted into a filler rod ready for wrapping into cigarette paper, cork sheets or webs of reconstituted tobacco or the like.

The apparatus of the present invention may constitute the distributor of a cigarette rod making machine or the like.

The fibrous material which can be treated in accordance with the method and in the apparatus of the present invention can constitute fragments of tobacco leaves or fragments of reconstituted tobacco as well as fibrous material which is utilized for the making of tobacco filters. The fragments of tobacco leaves may constitute shreds of tobacco ribs, tobacco stem and/or tobacco leaf laminae, as well as such fragments which are utilized for the making of cigars, cigarillos and the like.

The distributor of a cigarette rod making machine constitutes that apparatus which converts a relatively wide layer, carpet or sliver of comminuted tobacco into a relatively narrow stream ready for conversion into a filler rod. As a rule, the carpet or sliver is fed lengthwise on the upper stretch of a belt conveyor and is showered beyond the discharge end of such conveyor into a transversely extending channel wherein the descending tobacco particles form a growing tobacco stream. Such stream is transported lengthwise past one or more equalizing devices and is compacted to form a filler rod ready to be wrapped into cigarette paper to form a cigarette rod which can be severed at regular intervals to yield tobacco rod sections or plain cigarettes of unit length or multiple unit length. Many cigar or cigarillo making machines employ distributors whose construction is identical or quite similar to that of the just-described distributor for use in a cigarette rod making machine. The uniformity of distribution of fibrous particles in a continuous stream of tobacco or filter material depends on homogeneousness of the sliver or carpet which is converted into the stream. The homogeneousness of the stream in turn influences the uniformity of distribution of fibrous material in the ultimate product, such as plain or filter-tipped cigarettes, cigars or cigarillos as well as filter rod sections.

SUMMARY OF THE INVENTION An object of the invention is to provide a novel and improved method of manipulating comminuted interlaced fibrous material for the purpose of forming a continuous sliver or carpet and for thereupon converting such sliver into a narrow stream of at least substantially separated or loose fibrous particles.

Another object of the invention is to provide a method of enhancing the uniformity or homogeneousness of a carpet or sliver of fibrous material, such as comminuted tobacco leaves.

A further object of the invention is to provide a novel and improved apparatus for converting a relatively large supply of fibrous material into a continuous sliver or carpet having a width which is substantially greater then its height and containing a mass of fibrous particles in uniform distribution such as is best suited for conversion of the sliver into a narrow stream.

Still another object of the invention is to provide a novel and improved distributor for use in cigarette rod making and similar machines.

Another object of the invention is to provide a novel and improved distributor for particles of fibrous filter material.

The improved method is utilized for the forming of a continuous homegeneous stream of fibrous material, such as comminuted tobacco leaves. The method comprises the steps of establishing a relatively large first supply of fibrous material, withdrawing from the first supply fibrous material in the form of a continuous layer having a width preferably greatly exceeding its height and transporting the layer lengthwise into a predetermined path which extends along successive first and second stations, removing successive increments of the layer from the path at the first station and propelling the fibrous material of the thus removed increments into the second station with attendant pronounced separation of the thus propelled material, accumulating at the second station a relatively small floating second supply of separated material, and withdrawing from the second supply a continuous sliver of separated material. The height of the sliver is preferably only a small fraction of its width, and the distribution of fibrous material in the sliver is suited for conversion of the sliver into a continuous narrow stream of separated fibrous material.

The method may comprise the additional steps of monitoring the quantity of fibrous material in the second supply and regulating the rate of withdrawal of material from the first supply as a function of changes in the quantity of material in the second supply so as to maintain the quantity of material in the second supply within a predetermined range. Still further, the method may comprise the additional step of equalizing the sliver preferably immediately downstream of the second station. The second withdrawing step may comprise removing from the second supply separated fibrous material at a rate exceeding a predetermined rate, and the equalizing step then preferably comprises returning the surplus of the thus removed separated material into the second supply.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved stream forming apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic elevational view of a cigarette rod making machine incorporating a stream forming apparatus which embodies the invention;

FIG. 2 is an enlarged transverse vertical sectional view of the stream forming apparatus, substantially as seen in the direction of arrows from the line IIII of FIG. 1; and

FIG. 3 is a similar sectional view of a modified stream forming apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 1, there is shown a cigarette rod making machine which comprises an improved distributor of the type to be described in connection with FIG. 2. The distributor furnishes a continuous shower 410 of tobacco shreds (FIG. 2) which descend into an elongated channel 1 having a moving bottom wall constituting the upper stretch of an endless foraminous conveyor band 2. The upper stretch of the band 2 travels in a direction to the right, as viewed in FIG. 1, and transports the growing tobacco stream at a level above a perforated plate 3 constituting the top wall of a suction chamber 4. The purpose of the chamber 4 is to attract the growing tobacco stream 41d (see FIG. 2) to the upper side of the upper stretch of the conveyor band 2. This band delivers successive increments of the fully grown tobacco stream 41d into the circumferential groove of a suction wheel 6 which rotates in a counterclockwise direction, as viewed in FIG. 1, and compacts the tobacco stream. To this end, the bottom wall of the peripheral groove of the suction wheel 6 consists of foraminous material and rotates about a stationary suction chamber extending at least between the point of tobacco transfer from the band 2 onto the suction wheel 6 and a trimming station which accommodates a trimmer or equalizing device 8 of known design. The

equalizing device 8 removes the surplus of tobacco shreds from the stream to thus convert the stream into a continuous filler rod 9 which is removed from the groove by a tongue 11 and is attracted to the underside of an endless suction belt 12. The purpose of the belt 12 is to transfer the tiller rod 9 into a wrapping mechanism 18 which includes an endless band 17, a customary paster 19 and a conventional plate-like sealer 21.

The cigarette rod making machine of FIG. 1 further comprises a roll 14 of convoluted cigarette paper web 13 which travels through a splicing device 214, thereupon through an imprinting device 16 which applies printed matter to longitudinally spaced portions of the web 13, and thereupon onto the upper stretch of the band 17 in the wrapping mechanism 18. The mechanism 18 comprises a conventional device which serves to drape successive increments of the web 17 about successive increments of the tiller rod 9 to thus form a continuous wrapped tobacco rod 22. The paster 19 provides one marginal portion of the draped web 17 with a layer of adhesive and such marginal portion is thereupon folded over the other marginal portion and the resulting seam is heated by the sealer 21. FIG. 1 further shows a fresh roll 14a of convoluted cigarette paper web 13a. The leading end of the web 13a is held in the splicing device 214 and is automatically attached to the trailing end of the preceding web 13 when the supply of web 13 on the roll 14 is exhausted or nearly exhausted similar to that shown in the Wendt US. Pat. No. 3,586,006, for example. The printed matter which is applied to the webs 13 and 13a in the imprinting device 16 may represent the trademark of the manufacturer or other indicia or symbols. The wrapped tobacco rod 22 then passes through a cutoff 23 wherein an orbiting knife severs the rod 22 at regular intervals to produce a single file of plain cigarettes of unit length. Successive cigarettes of the single file of cigarettes issuing from the cutoff 23 are accelerated by a so-called kicker 24 to be propelled into successive flutes of a rotary transfer conveyor or drum 26. The conveyor 26 accumulates one or more rows of plain cigarettes of unit length and the cigarettes of such rows travel sideways and are ready to be introduced into conventional trays or chargers or directly into a filter cigarette making machine, not shown.

The distributor of the cigarette making machine of FIG. 1 is illustrated in FIG. 2. This distributor comprises a magazine or hopper 37 constituting a source of a main or first supply 36 of shredded tobacco. The distributor of FIG. 2 is a so-called gravity distributor. The main supply 36 in the magazine 37 is replenished at regular intervals or when necessary, for example, by way of a pneumatic conveyor, not shown. The distributor further comprises an endless conveyor belt 31 having entraining means here shown as outwardly extending carding 31a. The belt 31 is trained over three rollers 32, 33 34 at least one of which is driven in the direction indicated by arrow 38 so as to move the upper stretch of the belt 31 in the direction indicated by arrow 39. That stretch of the belt 31 which extends between the rollers 33 and 34 serves as a means for withdrawing a continuous layer 41 of tobacco shreds directly from the main supply 36 and for supplying successive increments of the layer 41 to the upper stretch extending between the

rollers

32 and 34. It will be noted that the stretch between the rollers 33 and 34 constitutes a moving side wall of the magazine 37. The height h of the layer 41 which reaches the upper stretch of the belt 31 is preferably a very small fraction of the width of such layer. The upper stretch of the belt 31 defines between the

rollers

32 and 34 an elongated substantially horizontal path which extends along a first or removing station A and along a second or settling station B. The station A accommodates a revolving removing device or impeller 42 here shown as a cylindrical brush having a horizontal axis which is parallel to the upper stretch of the belt 31 and is normal to the direction (arrow 39) of lengthwise movement of the layer 41. The purpose of the brush 42, which rotates at a high speed in the direction indicated by the arrow 43, is to propel successive increments of the layer 41 so that the particles or fragments 41a of tobacco forming such increments are caused to leave the upper stretch of the belt 31 and travel along a path indicated by arrow 56 to again settle or descend onto the upper stretch of the belt 31 at the settling station B. The peripheral speed of the brush 42 substantially exceeds the speed of lengthwise movement of the belt 31. The particles 41a which are propelled in the direction indicated by the arrow 56 have trajectories varying within a certain range but all such particles accummulate at the station B to form a relatively small floating intermediate supply 44 which contains loose or discrete shreds of tobacco. Thus, the propelling action of the brush 42 results in pronounced separation of interleaved or interlaced tobacco shreds so that the intermediate supply 44 at the station B accommodates a homogeneous body of tobacco particles. The bristles of the brush 42 are preferably soft. A carded refuser drum 46 rotates in a counterclockwise direction, as viewed in FIG. 2, immediately downstream of the station B to return back to the supply 44 any surplus of tobacco shreds which are entrained from the intermediate supply by the upper stretch of the belt 31. The drum 46 serves as a simple equalizing device which cooperates with the belt 31 to insure that the height of the sliver 41b which is transported by the belt downstream of the drum 46 is uniform all the way between the two marginal portions of the upper stretch of the belt 31.

The quantity of tobacco shreds in the intermediate supply 44 is monitored by a device including a photoelectric detector 47 of conventional design. The detector transmits signals to an amplifier 48 which in turn transmits signals to a servomotor 51 (e.g., an electromagnet) which can shift a refuser here shown as a rotary paddle wheel 49. The refuser wheel 49 rotates in a counterclockwise direction (see the arrow 52) and its preferably elastic paddles or blades 53 serve as a means for equalizing the layer 41 which is being withdrawn from the main supply 36. The servomotor 51 can move the axis of the paddle wheel 49 closer to or further away from the adjacent upwardly inclined stretch of the belt 31 to thereby change the height h of the layer 41. When the detector 47 transmits a signal which indicates that the intermediate supply 44 is reduced, the signal is amplified at 48 and is transmitted to the servomotor 51 which causes the axis of the paddle wheel 49 to move away from the adjacent stretch of the belt 31 so that the height of the layer 41 increases and the intermediate supply 44 is replenished in a fully automatic way. lnversely, when the intermediate supply 44 accumulates a maximum permissible quantity of tobacco shreds, the signal from the detector 47 causes the servomotor 51 to move the axis of the paddle wheel 49 closer to the upwardly inclined stretch of the belt 31 whereby the height h of the layer 41 decreases and the intermediate supply 44 is gradually reduced to the desired value. The detector 47 may comprise several light sources disposed at different levels and an equal number of photosensitive elements each of which is in line with the respective light source and produces a signal when the light beam from the respective source is free to impinge on its photosensitive surface.

A rapidly rotating picker roller or brush 54 is adjacent to the discharge end ofthe conveyor belt 31 opposite the roller 32. Its purpose is to propel successive increments of the sliver 41b from the carding 31a and to form the aforementioned shower 41c which descends into the channel 1 to form therein the narrow stream 41d which is entrained by the upper stretch of the foraminous belt 2 travelling above the perforated top plate 3 of the suction chamber 4. The picker roller 54 is preferably driven at a constant speed and rotated in a clockwise direction, as viewed in FIG. 2. The internal surfaces 1a and 1b of the channel 1 extend upwardly along and beyond the tobacco stream growing zone.

The operation of the distributor shown in FIG. 2 is as follows:

The belt 31 is driven in the direction indicated by the arrow 39 so that its upwardly inclined stretch between the rollers 33 and 34 withdraws a continuous layer 41 from the main supply 36 in the magazine 37. The paddle wheel 49 rotates in the direction indicated by the arrow 52 to determine the height h of the layer 41. Successive increments of the layer 41 reach the rapidly rotating brush 42 which propels the shreds along trajectories indicated by the arrow 56 whereby the shreds return onto the upper stretch of the belt 31 at the station B. The distance between the axis of the brush 42 and the upper stretch of the belt 31 is preferably such that the bristles of the rapidly rotating brush 42 expel all particles of the layer 41 from the carding 3111 at the station A. The upper stretch of the belt 31 draws from the intermediate supply 44 a continuous sliver 4117 which is equalized by the carding of the refuser drum 46 and advances into the range of bristles or teeth on the rapidly rotating member 54 which forms the shower 41 c descending into the channel 1 of the cigarette rod making machine.

If the intermediate supply 44 rises beyond a predetermined maximum permissible level, the detector 47 furnishes a signal to the amplifier 48 which causes the servomotor 51 to move the axis of the paddle wheel 49 toward the upwardly moving stretch of the belt 31 with attendant reduction in the height h of the layer 41. The adjustment of the wheel 49 is completed when the intermediate supply 44 contains the desired quantity of tobacco. If the level of tobacco in the intermediate supply 44 descends to a predetermined lowermost permissible level, the signal from the detector 47 causes the servomotor 51 to move the paddle wheel 49 away from the belt 31 so that the height h of the layer 41 increases and the supply 44 is replenished.

FIG. 3 illustrates a modified distributor. All such component parts of this distributor which are clearly analogous to or identical with the corresponding parts of the distributor shown in FIG. 2 are denoted by similar reference characters plus 100. The belt-shaped conveyor 31 of FIG. 2 is replaced by a carded drum 161 which draws tobacco shreds from a main supply 136 in a magazine 137 and cooperates with an adjustable paddle wheel 149, a rapidly rotating impeller brush 142 at the station A. and a carded refuser drum 146 located downstream of the staion B. Furthermore. the sliver 141D which is converted into the shower 141c accumulates on the upper stretch of an endless tape 164 which extends between the drum 161 and the channel 101. A picker roller 162 expels successive increments of the sliver 1141b from the carding of the drum 161 and the thus removed shreds advance into the range of a rapidly rotating winnower 163 which propels the lighter tobacco particles 141d onto the upper stretch of the tape 164 whereas the heavier tobacco particles l4le (mainly fragments of tobacco ribs and stem) are caused to strike against a baffle 166a and descend by gravity into a collecting receptacle 166. The upper stretch of the tape 164 advances in the direction of the arrow 167 and transports a highly homogeneous sliver 141D of tobacco shreds toward the roller at its discharge end to form the shower 1410 which descends into the channel 101 to form a continuous narrow tobacco stream ready to be converted into a filler rod. The operation of all other parts of the distributor shown in FIG. 3 is identical with or clearly analogous to the operation of similarly numbered parts in the distributor of H0. 2.

The detector 147 prevents excessive fluctuations in the quantity of separated tobacco shreds forming the floating supply 144; such excessive fluctuations could adversely affect the rate of withdrawal of shreds from the supply 144 to form the sliver 141b. The refuser 146 also serves to promote the formation of a homogeneous tobacco stream by insuring that each increment of the sliver 14117 at the station accommodating the picker 162 contains a predetermined quantity of at least substantially separated shreds.

FIG. 3 further shows a continuous layer 141 of comminuted tobacco leaving the magazine 137, the paddles 153 of the adjustable wheel 149, the arrow 143 indicating the direction of rotation of the brush 142, the arrow 139 indicating the direction of rotation of the conveyor 16!, the endless conveyor band 102, and the suction chamber 104.

An important advantage of the improved method and apparatus is that any fluctuations in the rate and which the conveyor 31 or ll6l removes tobacco shreds from the main supply 36 or 136 do not effect the homogeneousness of the sliver which is converted into the shower 410 or 141a. Fluctuations in the rate of tobacco removal from the main supply may be caused by changes in the level of tobacco in such main supply, by changes in the size of tobacco particles and/or by other factors. Such absence of dependency on the just discussed fluctuations is attributed to the formation of

intermediate supply

44 and 144 which contains loosened tobacco shreds ready to be converted into a continuous sliver of constant height and width and with uniform distribution of tobacco shreds therein. The loosening is brought about by the

impeller

42 and 142 at the station A. It was found that the formation of a homogeneous sliver of constant height and width can be achieved much more readily when the sliver is being withdrawn from a relatively small supply of shreds rather than from a large supply such as the main supply 36 or 136. However, the improved distributor not only establishes a relatively small intermediate supply but it also insures that such intermediate supply contains a mass of loose or separated tobacco shreds which can be readily converted into a highly satisfactory sliver 41b or l4lb.

The

impeller

42 or 142 at the station A performs another important function, namely, it removes from the carding of the conveyor 31 or 161 all or nearly all particles of tobacco so that, when the thus relieved carding reaches the station B, it can properly engage and entrain a uniform sliver 41b or l4lb for transport toward the shower-forming zone. Since the belt 31 or drum 161 extends beyond the station B, it is not necessary to provide a discrete conveyor for transport of the sliver 41b or l4lb. This reduces the space requirements and initial cost of the distributor.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. In an apparatus for forming a continuous stream of fibrous material, particularly a stream of comminuted tobacco particles, a combination comprising a source of supply of fibrous material; conveyor means arranged to receive from said source fibrous material in the form of a continuous layer having a width exceeding its height and to transport the layer lengthwise into a predetermined path extending along successive first and second stations; removing means provided at said first station and including a device for propelling successive increments of the moving layer from said first to said second station whereby the fibrous material of such increments moves along a second path with attendant separation of fibrous material to form at said second station a relatively small floating second supply of separated material, said conveyor means being arranged to withdraw from said floating supply a continuous sliver for movement with said conveyor means along said first path; and means for monitoring the quantity of fibrous material in said floating supply and means for regulating the quantity of fibrous material in unit lengths of said layer in response to signals from said monitoring means.

2. A combination as defined in claim 1, wherein said conveyor means comprises means for removing fibrous material from said source and said apparatus further comprising refuser means for equalizing the layer upstream of said first station.

3. A combination as defined in claim 2, wherein said removing means is arranged to propel fibrous material at a speed greatly exceeding the speed of the layer on said conveyor means.

4. A combination as defined in claim 1, wherein said conveyor means comprises an endless carded conveyor belt.

5. A combination as defined in claim 1, wherein said conveyor means comprises a carded drum.

6. A combination as defined in claim 1, wherein said propelling device comprises a rotary brush.

7. A combination as defined in claim 1, further com prising refuser means cooperating with said conveyor means downstream of said second station to equalize said sliver.

8. A combination as defined in claim 1, wherein said monitoring means comprises photoelectric detector means and said regulating means comprises rotary refuser means.

9. A combination as defined in claim 1. wherein said conveyor means comprises a portion which draws the fibrous material of said layer directly from said source of supply.

10. A combination as defined in claim 1, further comprising means for converting said sliver into a continuous narrow stream of fibrous material.

11. In a method of forming a continuous homogeneous stream of fibrous material, such as comminuted tobacco leaves, the steps of establishing a relatively large first supply of fibrous material; withdrawing from said first supply fibrous material in the form of a continuous layer having a width greatly exceeding its height and transporting the layer lengthwise into a predetermined path extending along successive first and second stations; withdrawing successive increments of the layer from said path at said first station and propelling the fibrous material of the thus removed increments to said second station with attendant separation of propelled fibrous material; accumulating at said second station a relatively small floating second supply of separated fibrous material; monitoring the quantity of fibrous material in said second supply and regulating the rate of withdrawal of material from said first supply as a function of changes in the quantity of material in said second supply so as to maintain said quantity of material in said second supply within a predetermined range; and withdrawing from said second supply a continuous sliver of separated fibrous material to form said stream.

which is removed from said second supply contains a surplus with respect to that required in said homogenized stream of fibrous material, said equalizing step comprising returning said surplus from the thus removed separated material into said second supply.

Claims

7. A combination as defined in claim 1, further comprising refuser means cooperating with said conveyor means downstream of said second station to equalize said sliver.

9. A combination as defined in claim 1, wherein said conveyor means comprises a portion which draws the fibrous material of said layer directly from said source of supply.

12. In a method as defined in claim 11, the additional step of equalizing the sliver downstream of said second station.

13. In a method as defined in claim 12, wherein said second withdrawing step comprises removing separated fibrous material from said second supply at a rate exceeding a predetermined rate so that the material which is removed from said second supply contains a surplus with respect to that required in said homogenized stream of fibrous material, said equalizing step comprising returning said surplus from the thus removed separated material into said second supply.