US3613692A

US3613692A - Apparatus for building a continuous tobacco stream

Info

Publication number: US3613692A
Application number: US554505A
Authority: US
Inventors: Jurgen Gomann
Original assignee: Hauni Werke Koerber and Co KG
Current assignee: Koerber AG
Priority date: 1965-06-02
Filing date: 1966-06-01
Publication date: 1971-10-19
Anticipated expiration: 1988-10-19
Also published as: DE1296557B; GB1083249A

Abstract

A tobacco stream is formed by showering tobacco particles into a current of suction air which flows across an elongated stream building zone defined by a channel wherein a foraminous belt travels lengthwise to transport the particles of the resulting growing tobacco stream. The flow of air across the conveyor is throttled by a valve which is adjacent to the conveyor and whose throttling action decreases in the direction of tobacco travel all the way between the ends of the stream building zone.

Description

United States Patent Inventor Jurgen Gornann Hamburg-Lohbrugge, Germany 554,505

June 1, 1966 Oct. 19, 1971 Hauni-Werke Koerber & Co. K. G. Hamburg, Germany June 2, 1965 Germany Appl. No. Filed Patented Assignee Priority APPARATUS FOR BUILDING A CONTINUOUS TOBACCO STREAM 2 Claims, 10 Drawing Figs.

U.S. Cl 131/84 8,

Int. Cl A24c 05/18 Field of Search l3l/61,6l B, 84, 84 B, 84 C; 198/193, 184, DIG. 7

References Cited UNITED STATES PATENTS 4/1962 Labbe 131/61 1,869,395 8/1932 Stelzer 131/84 C UX 1,999,120 4/1935 Werner 131/84 B UX 2,684,678 7/1954 Walter et al. 131/84 X 2,984,594 5/1961 Runton 198/193 X 3,039,473 6/1962 Schubert 131/84 C 3,094,127 6/1963 Gar'nberini 131/84 B X 3,224,566 12/1965 Elliott 198/193 FOREIGN PATENTS 251,138 4/1964 Australia 131/21 D 1,109,581 6/1961 Germany 131/84B Primary Examiner.loseph S. Reich Attorney-Michael S. Striker ABSTRACT: A tobacco stream is formed by showering tobacco particles into a current of suction air which flows across an elongated stream building zone defined by a channel wherein a foraminous belt travels lengthwise to transport the particles of the resulting growing tobacco stream. The flow of air across the conveyor is throttled by a valve which is adjacent to the conveyor and whose throttling action decreases in the direction of tobacco travel all the way between the ends of the stream building zone.

PAIEmEmm 19 ran 8,613,692

SHEET 2 OF 2 I N VENTOR.

APPARATUS FOR BUILDING A CONTINUOUS TOBACCO STREAM The present invention relates to the production of wrapped tobacco rods in general, and more particularly to improvements in a method and apparatus for building a continuous tobacco stream which can be converted into the filler of a wrapped tobacco rod. Still more particularly, the invention relates to improvements in a method and apparatus for building a continuous tobacco stream with the help of air currents which advance, or assist in advancing of tobacco particles toward and thereupon retain such particles in an elongated conveyance path.

It is already known to subject the particles of a travelling tobacco stream to the action of suction so that such particles adhere to the surface of a conveyor belt which advances the stream toward a wrapping station. Reference may be had to German Patent No. 673,628 or to US Pat. No. 3,030,965. The latter patent discloses a cigarette making machine wherein particles of tobacco are conveyed in a current of suction air to accumulate on a travelling foraminous belt and to form thereon a tobacco stream whose height increases in the direction of travel of the belt. A serious drawback of such machines is that the current of air subjects different zones of the developing tobacco stream to different compressive stresses because the permeability of the developing tobacco stream decreases with increasing height. The air current follows the path of least resistance and passes mainly through that portion of the developing stream which is relatively thin and offers less resistance to the flow of air so that the tobacco particles forming such thin portion are subjected to excessive compressive stresses. In order to insure that each portion of the developing stream undergoes requisite compression, such as is necessary to at least prevent relative movement between the foraminous belt and the particles of the developing tobacco stream, the machine must be equipped with a device which produces a very strong current of suction air. A large percentage of such air is wasted and the strong current of suction air often subjects certain portions of the developing tobacco stream to excessive compression in addition to the highly undesirable drying of tobacco particles and expulsion of aromatic substances therefrom.

Accordingly, it is an important of the present invention to provide a novel and improved method of building a continuous tobacco stream from discrete particles which are conveyed in a current of air and to regulate the action of the air current upon the developing tobacco stream in such a way that each stratum of the tobacco stream is subjected to compressive stresses of desired magnitude whereby the magnitude of such compressive stresses can remain constant all the way from the one to the other end of the developing tobacco stream.

Another object of the invention is to provide a method of the just outlined characteristics according to which the current or currents of air which advance or assist in advancing of tobacco particles into a conveyance path can also perform a highly beneficial equalizing action by eliminating or by at least reducing the height of hills or crests and the depth of valleys which might be observable in the exposed surface of a freshly formed tobacco stream.

A further object of the invention is to provide a method of building, a continuous tobacco stream from pneumatically fed tobacco particles according to which the quantity of air necessary to build a satisfactory tobacco stream of reasonably constant cross section is much less than that required for the practice of conventional methods.

An additional object of the invention is to provide a method according to which a continuous tobacco stream can be built up from pneumatically supplied tobacco particles with a minimum of breakage of such particles, without subjecting the particles to undesirable compressive stresses, and at a rate required in a modern high-speed cigaretteor cigar-making machine.

Still another object of the invention is to provide a novel apparatus which may be utilized in practicing of the above outlined method.

A concomitant object of the invention is to provide the apparatus with a novel pneumatic airflow regulating system which protects the particles of the developing tobacco stream from excessive pneumatic compression, excessive drying and/or expulsion of desirable aromatic and other ingredients.

A further object of the invention is to provide the improved apparatus with novel means for pneumatically equalizing a freshly formed tobacco stream.

Another object of the invention is to provide the apparatus with novel means for transferring the tobacco stream from a first conveyor on which the stream is formed to a second conveyor.

Briefly stated, one feature of my present invention resides in the provision of a method of building a continuous tobacco stream. Basically, the improved method comprises the steps of conveying a current of air across an elongated stream building zone of a predetermined path at a rate which increases in a direction from the one toward the other end of the stream building zone, feeding into the air current a continuous shower of tobacco particles at a substantially constant rate so that the thus showered particles are entrained toward and into the predetermined path, and advancing the tobacco particles in the direction from the one toward the other end of the stream building zone immediately upon entry into the predetermined path so that such particles form a continuous tobacco stream whose height increases in the direction from the one toward the other end of the stream-building zone as a result of continued deposition of additional tobacco particles on top of the particles which advance in the predetermined path whereby the developing tobacco stream offers to the passage of air a resistance which also increases in the direction from the one toward the other end of the stream building zone. The rate at which the flow of air increases in the aforementioned direction prior to admission of tobacco particles into the air current can be selected in such a way that the increasing resistance of the developing tobacco stream fully compensates for the increase in the rate of airflow, and the action of the air current upon the exposed surface of the developing tobacco stream is preferably such that the air current holds the particles of the developing tobacco stream against movement with reference to each other.

The flow of the air current across the developing tobacco stream is preferably induced by suction. The shower of tobacco particles is preferably formed by conveying a wide carpet of tobacco particles lengthwise toward the air current at right angles to the direction in which the developing tobacco stream moves in the stream-building zone, and introducing the leading edge of the tobacco carpet into the air current to thus form the aforementioned shower. The width of the carpet at least approximates but preferably equals the length of the streambuilding zone.

The tobacco stream which leaves the stream-building zone is then advanced through a second elongated zone of the aforementioned path which is located immediately downstream of the stream-building zone, and a second current of air is conveyed across the second zone at a rate which is at least nearly constant from the one to the other end of the second zone. Such second air current is preferably conveyed at a rate which is just sufficient to hold against relative movement tobacco particles in such portions of the tobacco stream whose height equals the average height of the tobacco stream leaving the stream-building zone. The two air currents are preferably conveyed substantially at right angles to the predetermined path of the tobacco stream and the sides of the tobacco stream in both zones of such path are preferably confined by suitable walls to direct the air currents across the tobacco stream. The width of the stream-building zone is a small fraction of its length and the tobacco particles are preferably showered into the first air current uniformly from the one to the other end of the stream-building zone so that the height of the developing tobacco stream increases gradually. The resistance offered by successive portions of the developing tobacco stream to the passage of air can be selected in a way to fully compensate for increasing rate of airflow in the absence of tobacco particles in such air current.

In the accompanying drawings:

FIG. 1 is a schematic side elevational view of a cigarettemaking machine including a tobacco-stream-building apparatus which embodies one form of my invention, the distributor which feeds tobacco particles into the stream building or forming zone being shown in partial section;

FIG. 2 is an enlarged transverse vertical section through the stream-building zone substantially as seen in the direction of arrows from the line II--II of FIG. 1;

FIG. 3 is a top plan view of a valve which is utilized in the stream-building apparatus, substantially as seen in the direction of the arrow III in FIG. 2 with certain additional parts of the apparatus omitted or broken away;

FIG. 4 is a fragmentary transverse vertical section across the stream-building zone of a slightly modified machine;

FIG. 5 is an enlarged fragmentary top plan view of a modified valve which may be utilized in the improved apparatus, the view of FIG. 5 being taken in the direction of the arrow V in FIG. 4;

FIG. 6 is a similar top plan view of the modified valve but showing that portion of the valve which is located in the stream advancing or conveying zone;

FIG. 7 is an enlarged fragmentary side elevational view of a portion of the machine shown in FIG. 1, with certain parts broken away;

FIG. 8 is a fragmentary transverse vertical section as seen in the direction of the arrows from the line VIII-VIII of FIG. 7;

- FIG. 9 illustrates a schematic diagram of the electrical circuit and a portion of the machine shown in FIG. 1; and

FIG. 10 is a transverse vertical section as seen in the direction of arrows from the line XX of FIG. 9.

Referring first to FIG. 1, there is shown a continuous cigarette-making machine which comprises a wrapping mechanism 2 disposed at a level above a distributor 4, the function of this distributor being to feed a continuous and uniform shower of tobacco particles which is used to build up a continuous tobacco stream 106. The outlet of the distributor 4 is located at a level above an elongated stream-building zone A forming the first part of an elongated substantially horizontal path in which the tobacco particles are conveyed in a current of suction air. The stream-building zone A is adjacent to the upper side of the upper stringer of an endless conveyor belt 24 consisting of foraminous material so that the current of air can pass therethrough. The belt 24 is trained around a series of

rollers

26, 28 and 30. The roller 26 is driven to advance the upper stringer of the belt 24 in a direction to the right, as viewed in FIG. 1, the lengthwise of the aforementioned path. The

rollers

28, 30 include rollers which serve solely as a means for guiding the belt 24 and rollers which maintain the belt under requisite tension. The tobacco stream 106 which is built up on the upper stringer of the conveyor belt 24 is then transferred into the circumferential groove of a second ,conveyor including a suction wheel 8. As clearly shown in FIG. 1, the circumferential groove receives the tobaccostream 106 in the region of the lowermost point of the suction wheel 8 and the stream travelling with the suction wheel 8 is then equalized by a suitable trimming device 18 to form a trimmed tobacco filler rod which is thereupon transferred onto the upper stringer of an endless conveyor belt 12. The means for transferring the filler rod from the groove of the suction wheel 8 onto the belt 12 comprises a plurality of transfer devices including a mechanical stripping member 10a which can extend into the groove of the wheel 8, and an endless transfer belt 10 which overlies the stripping member 10a. Furthermore, the wheel 8 can accommodate a plenum chamber and a nozzle which directs a jet of compressed gas upwardly in a region adjacent to the stripping member 10a so that such jet initiates or effects evacuation of the filler rod from the groove of the wheel 8.

The member 10a then merely removes from the groove any such tobacco particles which might adhere to the bottom wall in the groove downstream of the aforementioned nozzle. Reference may be had to US. Pat. No. 3,422,820 to Korber et al. The wrapping mechanism 2 is of known design and serves to wrap the filler rod into a tape 12a of cigarette paper or the like so that the thus wrapped filler rod forms a continuous cigarette rod which is thereupon severed by a cutting device 14 to yield a single file of cigarettes 172. Such cigarettes enter the axially parallel pockets of a drum-shaped conveyor 16 and are advanced to a packaging machine, to storage or to a filter-cigarette-making machine in a manner not forming part of the present invention.

The trimming device 18 may be positioned in such a way that its cutter or cutters remove tobacco particles which extend from the circumferential groove of the suction wheel 8, i.e., beyond the peripheral surface 20 of this wheel.

The upper stringer of the foraminous belt 24 travels in a substantially U-shaped channel 6 which is shown in FIGS. l and 3 and wherein the tobacco particles showered by the distributor 4 are caused to form a continuous tobacco stream 106. The channel 6 defines the elongated path for the tobacco stream. The upper stringer of the belt 24 constitutes the travelling bottom wall for the tobacco stream in the channel 6 and advances in a direction toward the lowermost point of the suction wheel 8. This channel 6 is located directly above a stationary suction chamber 32 forming part of a pneumatic air current conveying unit and serving to draw through the belt 24 a current of air which compels the tobacco particles showered by the distributor 4 to advance toward the belt 24 and to share the lengthwise movement of this belt in a direction toward the suction wheel 8. The suction chamber 32 has an outlet 44 which is connected with a suction pipe 34 leading to the suction side of a fan 36 on an analogous suction generating device.

The exact construction of the drive for the belts l0, 12, 24, for the suction wheel 8, trimming device [8, cutting device 14 and conveyor 16 forms no part of the present invention. Such drive will rotate, reciprocate or otherwise actuate the movable parts of the cigarette making machine at speeds which are necessary to produce the cigarettes 172 at rates expected in a modern cigarette making machine which must turn out up to 2,000 cigarettes per minute.

The stream-building zone A is followed by a second zone B which is a stream conveying or advancing zone, and the zone B is followed by a third zone C which is a transfer zone and where the tobacco stream 106 is transferred into the circumferential groove of the suction wheel 8. The conveying zone B accommodates a pair of guide walls 33 which direct a current of air against the tobacco stream 106 and at right angles to the direction of movement of the conveyor 24 to hold the stream against the upper stringer of the conveyor with a predetermined force.

The suction chamber 32 is provided with a normally closed flap 35 which may be opened to admit air into the interior of the suction chamber so that the fan 36 then draws air directly through the inlet opening which is exposed by the flap 35.

FIG. 2 illustrates certain details of the distributor 4, the channel 6 and the suction chamber 32 in vertical section. The channel 6 comprises a substantially U-shaped trough having a fixed bottom wall or base 38 and two sidewalls or flanges 40 spaced from each other and extending with the base 38 along the full length of the zones A and B. The upper side of the base 38 is formed with a shallow recess 42 which accommodates the upper stringer of the conveyor belt 24. The latter preferably consists of woven filamentary synthetic plastic material and each of its zones has the same degree of permeability.

The underside of the base 38 is formed with a relatively deep recess 46 which is located opposite the recess 42 and communicates with the interior of the suction chamber 32. The web 48 between the

recesses

42 and 46 forms a sieve or filter and is formed with suitably distributed and dimensioned apertures or

orifices

84, 86, 88, 90 and 92 which will be fully described hereinafter. This web 48 (hereinafter called valve) performs a very important function in that it insures that each zone of the growing or developing tobacco stream 100 in the stream-building zone A is subjected to identical or nearly identical pressure by a current or air which flows into the suction chamber 32 across the developing stream in a direction from the upper side of the valve 48 into the recess 46 and thence into the interior of the suction chamber. The direction of the airflow is indicated in FIG. 2 by the arrow 52. It is clear that the valve 48 need not form an integral part of the bottom wall 38.

The space 22 between the flanges 40 accommodates the lower marginal portions 62 of two

sidewalls

56, 58 which diverge upwardly and away from the upper stringer of the belt 24. The

sidewalls

56, 58 form part of a chute60 which further includes two

upright end walls

94, 96 shown in FIG. 3. The lower marginal portions 62 of the

sidewalls

56, 58 are parallel to each other and extend into the space 22 between the flanges 40, see FIG. 2. It will be noted that the marginal portions 62 extend to a level directly above the upper stringer of the belt 24. The upper marginal portion 64 of the sidewall 58 extends to the lower stringer 70 of an endless feed belt 68 which forms part of the distributor 4 and conveys to the chute 60 a continuous relatively wide carpet or fleece 80 of tobacco particles. The belt 68 is trained around a roller 72 which is located above the inlet of the chute 60 and is spaced from an arcuate deflector 74. After leaving the upper stringer of the belt'68, the leading edge of the carpet 80 forms a shower 75 which descends between the

walls

56, 58, 94 and 96 of the chute 60 and accumulates on the upper stringer of the belt 24. The deflector 74 overlies the sidewall 56 and forms therewith an elongated nozzle 76 for admission of additional air into the interior of the chute 60.

The suction chamber 32 comprises a housing 78 which is sealingly attached to the base 38 by means of brackets 82.

In FIG. 3, the major part of the upper stringer of the belt 24 is broken away to reveal the apertures or orifices in the valve 48. The belt 24 is shown only in the left-hand part of FIG. 3. The cross-sectional area of each aperture 86 is greater than the cross-sectional areas of the apertures 88 but smaller than the cross-sectional areas of the apertures 84. The cross-sectional areas of the apertures 90 are smaller than those of the apertures 88. In other words, if the feed belt 68 does not supply tobacco to the chute 60 and if the fan 36 is on, each successive unit length of the valve 48 admits more air than the preceding unit length. It can be'said that the permeability of the valve 48 increases in a direction from the left-hand end toward the right-hand end of the stream-building zone A. The cross-sectional area of each aperture 92 in the valve 48 downstream of the chute 60 (i.e., in the conveying zone B) is preferably the same. The stream building zone A extends between the

end walls

94, 96 of the chute 60 and the zone B is immediately adjacent to the right-hand (downstream) end of the zone A but terminates short of the region where the tobacco stream- 106 leaves the upper stringer of thebelt 24. The guide walls 33 begin at the right-hand end wall 96 of the chute 60. It can be said that the guide walls 33 constitute extensions of the

sidewalls

56 and 58; however, their height may be considerably less. The lower marginal portions of the guide walls 33 extend into the space 22 between the flanges 40 in the same way as shown for the lower marginal portions 62 of the

sidewalls

56, 58. The elongated path for the tobacco particles begins at the left-hand end wall 94 of the chute 60 and terminates at the point where the filler rod is wrapped into the tape 12a. From there on, the particles are fully confined in the tubular wrapper and form therewith the cigarette rod 170 shown in the upper part of FIG. 1.

F lGS..7 and 8 illustrate details of the structure in the zones B and C. The minimum distance between the right-hand end turn of the belt 24 and the peripheral surface of the suction wheel 8 is in the range of a few millimeters, for example, three millimeters. The downstream ends of the guide walls 33 are formed with concave top faces which are closely adjacent to the adjoining portion of the peripheral surface 20. Thus, each of the guide walls 33 terminates in a pointed wedgelike tip which can extend slightly beyond the transfer zone C. An imaginary upward extension 66 of the front end wall 102 of the housing 78 of the suction chamber 32 intersects the peripheral surface 20 of the suction wheel 8 at a distance from the upper stringer of the belt 24 which corresponds substantially to the average height 104 of the tobacco stream 106. In the transfer zone C, the apertures or orifices 92 of the valve 48 are outside of the confines ofthe suction chamber 32, i.e., the underside of this valve is surrounded by air at atmospheric pressure.

The suction wheel 8 is formed with a circumferential groove 108 and comprises a foraminous annular member 110 which bounds the innermost part of the groove 108. The annular member 112 carries radially inwardly extending partitions defining between themselves an annulus of compartments 114 each of which communicates with the groove 108 through the perforations of the annular member 110. The partitions 112 travel around a stationary annular baffle 116 which seals some of the adjoining compartments 114 from each other and forms the outer wall of a stationary suction chamber 120. The latter is connected to a suction pipe 122 and the baffle 116 has an arcuate slot 118 extending across and beyond the transfer zone C so that the tobacco stream 106 reaching the imaginary extension 66 of the front end wall 102 is subjected to the ac tion of an upwardly directed third air current passing through the apertures 92 of the valve 48, through the belt 24, across the groove 108 and through the annular member 110, through the compartments 114, through the slot 118 and suction chamber 120, and into the suction pipe 122. The latter is connected to the fan 36 or to a separate suction-generating device. The slot 118 preferably extends in a counterclockwise direction and all the way to or close to the topmost portion of the groove 108, namely, to the region where the filler rod is caused to leave the groove 108 and to advance onto the upper stringer of the belt 12. Actually, the filler rod does not come in direct contact with the belt 12 because it is fed onto the tape 12a.

The third current of air which enters the slot 118 of the stationary baffle 116 serves to facilitate or to effect transfer of the tobacco stream 106 from the upper stringer of the belt 24 into the groove 108 of the suction wheel 8 and also to hold'the tobacco stream in the groove 108 against the action of centrifugal force while the stream advances toward, past and beyond the trimming device 18. The slot 118 in the baffle I16 need not extend beyond the transfer zone C if the tobacco stream travelling in the groove 108 is held against centrifugal force by other means, for example, by a belt which is turned around the right-hand part of the peripheral surface 20 from the rightmost roller 28 and to the trimming device 18 (see US. Pat. No. 2,868,2l l to Richter). The pressure exerted by the third current of air flowing into the slot 118 need not exceed a pressure which is necessary to hold the tobacco stream in the groove 108 against the action of centrifugal force. However, the pressure of such current of air may be increased if it is desired to pneumatically compact the tobacco stream prior to actual trimming (see US. Pat. No. 3,413,979 to Korber). Also, the apparatus may comprise one or more mechanical compacting devices for the tobacco stream in the groove 108 and the trimming device 18 may be replaced by a series of two or more trimming devices which remove surplus tobacco in a plurality of successive steps. Reference may be had tothe copending application Ser. No. 634,740 filed by Richter on Apr. 28, 1967 and assigned to the same assignee.

The space 22 between the flanges 40 of the channel 6 is of rectangular or square cross-sectional outline (see FIGS. 2 and 8) but the width of the groove 108 in the peripheral surface 20 of the suction wheel 8 increases radially outwardly so that the cross-sectional area of this groove is of substantially trapeziform outline. The open sides 50, 54 of the space 22 and groove 108 are shown in FIG. 8, and the distance between the annular member 110 and the upper stringer of the belt 24 in the region between the zones B and C preferably equals twice the average height 104 of the tobacco stream 106.

Referring now to FIGS. 9 and 10, the flap 35 is rockable about the horizontal pintle of a hinge 128 carried by the housing 78 of the suction chamber 32 and normally seals an inlet opening 124 in the sidewall 126 of the housing 78. The opening 124 is preferably adjacent to the outlet 44. The control means for moving the flap 35 between open and closed positions comprises an arm 130 having a bifurcated portion 132 receiving a pivot pin for the armature 134 of an electromagnet 136. The terminals 138 of the electromagnet 136 are connected to leads 140 and through such leads with a source 144 of DC current. The circuit of the electromagnet 136 further includes a switch having fixed contacts 141 and a movable contact 142 attached to the armature 147 of a second electromagnet 148. When the electromagnet 148 is deenergized, the armature 147 follows the bias of a helical expansion spring 146 and moves the contact 142 away from the contacts 141 to thereby open the circuit of the electromagnet 136. The terminals of the second electromagnet 148 are connected with leads 150 and this electromagnet is installed in the circuit of a source 156 of AC current. The circuit further comprises a master switch 158 and an electric motor 154. The numeral 152 denotes leads for the motor 154 and master switch 158. The motor 154 is the prime mover of the cigarette making machine shown in FIG. 1 and can drive all movable parts inclusive of the fan 36.

FIG. further shows an expansion spring 162 which also forms part of the aforementioned control means and tends to move the flap 35 to open position. Brackets 160 connect the electromagnet 136 to the housing 78 of the suction chamber 32.

The operation of the cigarette making machine shown in FIGS. 1 to 3 and 8 to 10 is as follows:

In order to start the machine, the person in charge closes the master switch 158 (FIG. 9) so that the motor 154 starts to drive the roller 26 for the conveyor belt 24, the shaft 8a of the suction wheel 8, the trimming device 18, the fan 36, the roller 72 for the feed conveyor belt 68, the belt 12, the device which feeds the tape 12a, the belt 10, the cutting device 14, the conveyor 16 and all other movable components of the machine. Before the master switch 158 is closed, the spring 162 maintains the flap 35 in o en position as shown in FIG. 10. Closing of the master switch 158 results in energization of the electromagnet 148 so that the armature 147 closes the

switch

141, 142 against the opposition of the spring 146. This completes the circuit of the electromagnet 136 which attracts the armature 134 and closes the flap 35 against the opposition of the spring 162. The fan 36 causes a current of air to flow through the nozzle 76 as well as along the upper stringer of the belt 68 and such current of air accelerates the particles which form the shower 75. The width of the carpet 80 on the upper stringer of the feed belt 68 equals or approximates the distance between the

end walls

94, 96 of the chute 60 so that the shower 75 descends onto each portion of the upper stringer of the belt 24 in the stream building zone A. The current of air flows through the developing tobacco stream 100 and passes through the apertures of the valve 48 to enter the recess 46 and the interior of the suction chamber 32. A very important function of such air current is to prevent relative movement between the particles of the developing stream 100 as well as to prevent relative movement between such particles and the upper stringer of the belt 24. The stream 100 resembles a wedge whose height increases in a direction from the end wall 94 toward the end wall 96, such shape of the developing stream 100 being due to the fact that tobacco particles which descend directly onto the belt 24 are covered by additional particles which descend while a unit length of the I belt 24 travels along the stream building zone A. On leaving the zone A the finished stream 106 has an average height 104 and this finished stream is then subjected to unvarying pressure of a second air current flowing through that portion of the belt 24 which is located in the conveying zone B. The distribution and dimensioning of the apertures 84, 86, 88, in the stream-building zone A can be selected in such a way that the air pressure upon the exposed surface of the developing tobac' co steam is uniform all the way from the end wall 94 to the end wall 96. In other words, progressively increasing resistance offered by the developing tobacco stream 100 to the passage of air therethrough can be fully compensated for by increasing permeability of the valve 48 so that each unit length of the developing stream 100 is subjected to the same compressive action. Such compressive action need not exceed that which is necessary to prevent slippage of tobacco particles with reference to the belt 24 and/or slippage of particles in the upper strata with reference to the particles in the lower strata of the developing tobacco stream 100. It can be said that, when there is no feed of tobacco particles by the belt 68, the rate of airflow through the valve 48 increases progressively from the end wall 94 toward the end wall 96. However, and since the tobacco stream offers a gradually increasing resistance to the flow of air through successive portions of the valve 48 in the stream building zone A, the rate of airflow through each such portion of the valve 48 can be the same. The pressure produced by the inflowing air current against the exposed upper side of the developing tobacco stream 100 is strong enough to prevent shifting of tobacco particles when the belt 24 is driven at a speed necessary to produce cigarettes 172 at a rate of up to 2,000 articles per minute.

The guide walls 33 direct the second air current flowing in the conveying zone B in a direction substantially at right angles to the upper stringer of the belt 24 and each unit length of the finished tobacco stream 106 is preferably subjected to the same compressive action. The guide walls 33 also prevent straying of tobacco particles from their path. Any such particles which tend to move away from the belt 24 are returned into the stream 106 by the current of inflowing air. Actually, the air current flowing through the belt 24 in the conveying zone B can perform a highly satisfactory equalizing action because the pressure produced by such air current is preferably calculated for the average height 104 of the finished stream 106. Thus, and if the exposed surface of the stream 106 is formed with hills and valleys, the air pressure upon the hills is less and the material forming such hills is swept away to enter the adjoining valleys. In other words, the zone B can also be called a coarse equalizing or smoothing zone. This will be readily understood because the air current flowing across the finished stream 106 will invariably try to follow the path of least resistance and will tend to bypass the hills where the resistance to the flow of air is greater than through the material below the valleys. If the pressure of air is not excessive, i.e., if the pressure is calculated for the average height 104 of the tobacco stream 106, the hills will disappear in a fully automatic way because their material cannot be held by air and is compelled to descend into the valleys directly behind such hills.

On leaving the conveying or coarse equalizing zone B, the tobacco stream 106 enters the transfer zone C. The stream 106 is then subjected to air pressure which acts in the opposite direction, i.e., the suction chamber in the suction wheel 8 receives a third current of air which flows upwardly through the apertures or orifices 92 located forwardly of the end wall 102 (see FIG. 7), thereupon through the adjoining portion of the belt 24, across the gap between the belt 24 and annular member 110, through the adjoining compartments 114, through the slot 118 and into the suction chamber 120. The direction of this third air current is indicated in FIG. 7 by an arrow 164. The suction chamber 120 draws air from the atmosphere as indicated by the arrows 166, and such air actually lifts the tobacco stream 106 off the upper stringer of the belt 24 and causes it to enter the tapering groove 108 in the peripheral surface 20 of the suction wheel 8. The cross-sectional configuration of the tobacco stream 106 is changed because the groove 108 is of trapeziform cross-sectional outline. The thus modified or reshaped tobacco stream 168 advances with the suction wheel 8 and is caused to move past the trimming device 18 which removes surplus tobacco so that the remainder of the tobacco stream 168 forms a filler rod of constant cross section. The surplus removed by the trimming device 18 may be fed to the distributor 4 or to a main source which supplies tobacco particles to the distributor.

If the nature of tobacco particles is such that they are not likely to form a tobacco stream of constant or nearly constant cross section. for example, when the shower 75 shown in FIG. 2 consists of long shreds of cigarette tobacco, the stream 168 in the groove 108 of the suction wheel 8 will contain particles which might extend well beyond the open side 54 of the groove 108. All such particles are then severed by the cutter orcutters of the trimming device 18 to make sure that the filler rod is ready for wrapping into the tape 12a. The'filler rod is transferred by the stripping member a and such transfer is assisted by the belt 10. If desired, the belt 10 may subject the tiller rod to at least some compression, and it is equally within the purview of my invention to omit the stripping member 10a and to. provide a suction chamber 10b (shown in FIG. 1) directly above the lower stringer of the belt 10 so that the belt 10 then transfers the tiller rod by suction. If the transfer unit includes such suction chamber 10b, the belt 10 must consist of foraminous material.

The operation of the wrapping mechanism 2 is well known from the art of cigarette-making machines and need not be described in detail. The cigarette rod 170 is severed by the cutting device 14 at regular intervals to yield cigarettes 172 of unit length or multiple unit length, and such cigarettes are directed into successive pockets of the revolving conveyor 16 to be advanced to storage, to a filter cigarette machine, to a testing device which discards defective cigarettes, or to a packaging machine.

If the operator wishes to arrest the machine, the master switch 158 of FIG. 9 is moved to open position to open the circuit of the motor 154 and electromagnet 148. The armature 147 follows the bias of the spring .146 and moves the contact 142 away from the fixed contacts 141 to. deenergize the electromagnet 136. The spring 162 (see FIG. 10) expands and opens the flap 35 to admit air into the suction chamber 32. In other words, even if the fan 36 is driven by a motor other than the motor ;154 of FIG. 9, the flow of air across the tobacco streams 100 and 106 is terminated as soon as-the operator opens the master switch 158. This prevents excessive drying of tobacco and expulsion of volatile ingredients which should remain in the tobacco. Even if the fully open flap 35 cannot admit all such air which is drawn by the fan 36, the rate of airflow through the tobacco streams 100 and 106 in the zones A and B is reduced to such an extent that the adverse effect upon thetobacco in the channel 6 is negligible.

Suction in the chamber 120 and rotation of the wheel 8 may be terminated simultaneously with or shortly after opening of the master switch 158 so that the reshaped tobacco stream 168 may be fully evacuated from the groove 108 before the particles forming this stream can drop by gravity. Of course, the situation is much simpler if the tobacco stream 168 is held in the groove 108 by one or more belts or by other mechanical retaining means (as shown in the Richter U.S. Pat. No. 2,868,2l I). In such a machine, the wheel 8 may be arrested as soon as the operator opens the master switch 158 because the tobacco stream 168 is invariably held in the groove 108 against the action of gravity or against the action of centrifugal force.

It is clear that the suction wheel 8 may be omitted and that the belt 12 may be arranged to receive the tobacco stream 106 directly from the belt 24. In such modified cigarettemaking "machines, the trimming device 18 can be located in or downstream of the zone B, either adjacent to the belt 24 or to the belt 12 (see U..S. Pat. No. 3,413,979 to Korber). Also, the means for transferring the tobacco stream from the belt 24 to the belt 12 may comprise one or more additional endless belts or like transfer devices. Still further, the distributor .4 may be provided at a level below the lower stringer of the belt 24 and the suction chamber 32 is then located above the upper stringer of the belt 24. In such cigarette-making machines, the valve 48 will.be located at a level above the lower stringer of the belt 24, i.e., between the belt and the suction chamber.

FIG. 4 illustrates a composite chute 260 which delivers a shower 275 of tobacco particles into the space 222 above the upper run of an endless foraminous conveyor belt 224. The trough which includes the base 238 and flanges 240 is similar to the trough of FIG. 2 but the valve 248 is provided with differently distributed and dimensioned apertures or orifices. The lower marginal portions 262 form a first chute 294a which receives tobacco particles from a second chute 294 formed by the sidewalls 264. The two chutes define between themselves two mirror symmetrical nozzles 276 which extend along the entire stream building zone. The

end walls

294, 296 of the composite chute 260 are respectively shown in FIGS. 5 and 6. The lower parts of the marginal portions 262 extend into the space 222 between the flanges 240 and are parallel to each other.

Referring to FIG. 5, it will be seen that the valve 248 is formed with two outer rows of apertures 284 of identical diameter and with a single median row 298 of

apertures

290, 288, 286 whose diameters increase in a direction from the rear end wall 294 toward the front end wall 296. In the zones B and C (see FIG. 6), the diameters of all apertures 292 in the median row 298 are the same. In other words, the permeability of each successive unit length of the valve 248 in the zone A increases in the direction of movement of the belt 224 but the penneability of each unit length of the valve 248 in the zones B and C is the same.

The main difference between the stream building apparatus of FIGS. 1 to 3 and 4 to 6 is that the upper chute 294 of FIG. 4 delivers tobacco particles solely by gravity and that the thus delivered particles are accelerated by currents of air entering through the nozzles 276. The optimum size of the nozzles 276 can be determined by simple experimentation.

Due to the fact that the median row 298 of

apertures

286, 288, 290, 292 admits more air than the outer rows of apertures 284, suction the central part of the space 222 is stronger than along the flanges 240. This is of advantage because the median portion of the space 222 normally contains more tobacco since the particles descending through the lower chute 294a exhibit at least some tendency to form a stream having a longitudinally extending central ridge whose sides slope toward the flanges 240. Since the flanges 240 are stationary, while the upper stringer of the belt 224 travels, friction between the flanges'and the adjoining particles of the tobacco stream is less pronounced if the height of the stream along the flanges is less than in the central part of the space 222 above the

apertures

286, 288, 290, 292.

A very important advantage of my methodand apparatus is that the particles of tobacco which are fed into and advance lengthwise through the stream buildingzone A are not subjected to excessive compressive streses'. This is due to the fact that, combined with the adjoining portion of the

valve

48 or 248, each unit length of the developing tobacco stream 100 can offer the same resistance to the flow of air therethrough. In other words, the combined resistance of the leftmost portion of the tobacco stream 100 shown in FIG. 1 (adjacent to the end wall 94) and of the adjoining portion of the valve 48 (apertures is preferably the same as that of the rightmost portion of the stream (adjacent to the end wall 96) and of the adjoining portion of the valve 48 (apertures 84). Of course, the apertures of the

valve

48 or 248 can be distributed in such a way that the resistance offered by successive unit lengths of the valve to the flow of air therethrough will not vary at a rate which isexactly proportional to changes in the height of the developing tobacco stream 100. For example, the exposed surface of the tobacco stream 100 can be subjected to an air pressure which increases gradually in a direction toward the conveying'zone B, and it is equally possible to distribute the apertures of the

valve

48 or 248 in the zone B in such a way that the air pressure upon the tobacco stream 100 will vary or will exceed the minimum pressure necessary to prevent relative movement between the tobacco particles and the

belt

24 or 224.

The apparatus of my invention constitutes an improvement over the apparatus which is disclosed in US. Pat. No. 3,039,473 to Schubert wherein a finished tobacco stream is subjected to gradually decreasing compressive action of an air current. The purpose of the Schubert apparatus is to allow for expansion of the tobacco stream prior to trimming, i.e., the retaining action of the air current passing through the tobacco stream is not selected with a view to insure that the air pressure upon successive unit lengths of the developing tobacco stream should remain constant and/or that such air pressure should be just sufficient to prevent relative movement between the foraminous conveyor and the particles of the stream.

it was found that the method and apparatus of my invention will produce a highly satisfactory tobacco stream if the particles fed into the stream building zone A are supplied in a current of suction air. Such current can be readily caused to pass through the developing tobacco stream 100 and will prevent rebounding of freshly supplied particles on the exposed surface of the stream. Of course, the invention also contemplates operation with currents of compressed air, for example, by placing the outlet of a blower in communication with the nozzle 76 or nozzles 276. However, it was found that the particles of tobacco advancing with a current of compressed air are much more likely to rebound on the surface of the developing tobacco stream 100 and, therefore, an apparatus operating with compressed air is preferably provided with means for subdividing the current into a plurality of smaller currents.

When the pressure exerted by an air current upon the exposed surface of the developing tobacco stream 100 at least suffices to prevent relative movement between the particles of the stream and/or between the tobacco particles of the stream and the

conveyor

24 or 224, the rate at which the stream 106 is being built up can be determined in advance and with a high degree of precision. Such rate will depend on the length of the stream building zone A, on the speed of the

belt

24 or 224, on the speed of the feed belt 68, on the thickness of the carpet 80 on the belt 68 and on the speed of the air current flowing in the direction of the arrow 52 shown in FIG. 2.

In a preferred embodiment of the invention, the length of the zone A is 1,000 mm., its width mm.; the speed of the feed belt 68 ranges between 45 and 50 m./min. whereas the speed of the

belt

24 or 224 may range from 130-180 m./min.

The permeability of the leftmost portion of the valve 48 is such, that the total area of the holes constitutes 25 percent of the unit valve-surface area, which permeability increases up to 40 percent at the rightmost portion of the valve.

The velocity of the air flowing through the tobacco stream and the holes of valve 48, due to a negative pressure of 180 mm. of water in the suction chamber 32 is such, that the hourly air-consumption amounts to 132 Nm.

In many presently known cigarette-making machines wherein a stream or rod of tobacco particles is conveyed by means of a perforated belt, the surfaces of the belt are normally roughened to prevent slippage between the tobacco particles and the belt. A serious drawback of such rough-surfaced belts is that they undergo considerable wear and must be replaced at frequent intervals. The wear is particularly pronounced in such portions of the belts which slide along stationary surfaces. Of course, the permeability of such belts also changes with progressing wear so that the rate of airflow therethrough cannot be predicted with requisite accuracy.

In accordance with a further feature of the present invention, the

belt

24 or 224 preferably includes woven or other wise interlaced filaments consisting of synthetic plastic material. A belt woven of plastic filaments can be made considerably smoother than a belt which is woven of textile threads made of other than plastic material. Of course, a smooth-surfaced belt undergoes less wear and its permeability remains unchanged for longer periods of time, not only because of reduced wear but also because many presently known plastic filaments exhibit considerable tensile strength and are less likely to permit uncontrolled stretching of the belt. Such stretching also brings about undesirable changes in permeability. Still further, many plastic filaments which can be used in the production of the

belt

24 or 224 exhibit a highly satisfactory resistance to abrasion. An endless woven nylon belt having a filament diameter of 0.6 mm. will meet the above-mentioned requirements. Preferably, the total surface area of the meshes allowing the air to flow through amounts to 30 percent of the total surface area of the belt.

The novel mode of transferring the tobacco stream 106 from the

belt

24 or 224 onto the conveyor which includes the suction wheel 8 insures that the tobacco stream enters the groove 108 of the suction wheel with a minimum of relative movement between the particles which form the stream. During transfer from the

belt

24 or 224, the particles of the stream 106 cover a distance (substantially radially of the suction wheel 8) which approximates or equals the average height 104 of the stream. All such particles cover substantially the same distance whereby the position of particles with reference to each other changes very little or not at all. This is highly desirable since the current of air traversing the stream 106 in the conveying zone B brings about a certain equalizing effect and such equalizing effect is not destroyed during transfer into the groove 108 despite the fact that the cross-sectional outline of the groove is or can be different from that of the space 22 between the guide walls 33. On the other hand, the feature that the width of the groove 108 increases toward the peripheral surface 20 of the suction wheel 8 brings about the important advantage that the stream 106 can be transferred without excessive compression so that the density of all zones of the stream 168 in the groove 108 remains constant. This is important if each successive unit length of the filler rod and wrapped tobacco rod 170 should have the same weight. In other words, the trimming device [8 will produce a filler rod each increment of which will have the same weight only if the density of the stream 168 is constant.

In accordance with a further feature of my invention, the method may be reversed by directing a current of air upwardly, as viewed in F IG. 1, and by thus forming a continuous shower 75 of tobacco particles from a tobacco stream 106 which is admitted into the zone A in a direction from the zone B.

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.

What is claimed as new and desired to be protected by Letters Patent is:

1. Apparatus for building a tobacco stream, comprising a channel defining an elongated stream-building zone; a foraminous conveyor arranged to travel lengthwise in a direction from the one toward the other end of said zone; an air permeable throttling valve adjacent to one side of said conveyor and extending along said zone, the permeability of said valve increasing in said direction all the way from said one to said other end of said zone; means for conveying a current of air across said zone toward and through said conveyor and thereupon through said valve whereby the throttling action of said valve decreases in said direction; a feed for supplying into said air current a shower of tobacco particles at the other side of said conveyor so that such particles deposit on and advance with the conveyor in said direction to form a developing tobacco stream whose height increases in said direction as a result of deposition of additional particles on top of the particles advancing with said conveyor whereby the developing tobacco stream offers to the passage of air a resistance which increases in said direction, a portion of said channel extending beyond said stream-building zone and said air conveying means comprising a suction chamber adjacent to said channel at said one side of said conveyor so that the current of air conveyed across said portion of said channel urges the tobacco stream against said conveyor, said suction chamber having a closable and exposable opening; means for drawing air from said suction chamber at a first rate when said opening is closed, said opening having a size such that air may flow therethrough at a faster second rate when the opening is exposed, and additional valve means arranged to expose or close said opening so that, when said opening is exposed, said suction chamber ceases to convey said current of air across the tobacco stream in said channel.

2, Apparatus for building a tobacco stream, comprising a I channel defining an elongated stream-building zone; a

foraminous conveyor arranged to travel lengthwise along a substantially straight path in a direction from the one toward the other end of said zone; an air permeable throttling valve adjacent to one side of said conveyor and extending along said zone, the permeability of said valve increasing in said direction all the way from said one to said other end of said zone; means for conveying a current of air across said zone toward and through said conveyor and thereupon through said valve whereby the throttling action of said valve decreases in said direction, a feed for supplying into said air current a shower of tobacco particles at a substantially uniform speed at the other side of said conveyor so that such particles deposit on and advance with the conveyor in said direction to form a developing tobacco stream whose height increases in said direction as a result of deposition of additional particles on top of the particles advancing with said conveyor whereby the developing tobacco stream offers to the passage of air a resistance which increases in said direction; and a suction conveyor having a tobacco stream receiving groove adjacent to but spaced from said first mentioned conveyor by a distance corresponding to the average height of the tobacco stream leaving said stream-building zone, said air conveying means comprising a suction chamber adjacent to said one side of said foraminous conveyor and terminating at the point where said groove receives the tobacco stream.

Claims

2. Apparatus for building a tobacco stream, comprising a channel defining an elongated stream-building zone; a foraminous conveyor arranged to travel lengthwise along a substantially straight path in a direction from the one toward the other end of said zone; an air permeable throttling valve adjacent to one side of said conveyor and extending along said zone, the permeability of said valve increasing in said direction all the way from said one to said other end of said zone; means for conveying a current of air across said zone toward and through said conveyor and thereupon through said valve whereby the throttling action of said valve decreases in said direction, a feed for supplying into said air current a shower of tobacco particles at a substantially uniform speed at the other side of said conveyor so that such particles deposit on and advance with the conveyor in said direction to form a developing tobacco stream whose height increases in said direction as a result of deposition of additional particles on top of the particles advancing with said conveyor whereby the developing tobacco stream offers to the passage of air a resistance which increases in said direction; and a suction conveyor having a tobacco stream receiving groove adjacent to but spaced from said first mentioned conveyor by a distance corresponding to the average height of the tobacco stream leaving said stream-building zone, said air conveying means comprising a suction chamber adjacent to said one side of said foraminous conveyor and terminating at the point where said groove receives the tobacco stream.