US3709274A

US3709274A - Method and apparatus for regulating output in tobacco cutting machines

Info

Publication number: US3709274A
Application number: US00054357A
Authority: US
Inventors: J Marek; G Hayn
Original assignee: Austria Tabakwerke AG
Current assignee: Austria Tabakwerke AG
Priority date: 1969-07-14
Filing date: 1970-07-13
Publication date: 1973-01-09
Anticipated expiration: 1990-01-09
Also published as: CH526275A; GB1289279A; AT292533B; DE7026307U; DE2034689A1; FR2054269A5

Abstract

The cut output of a tobacco cutting machine is regulated by measuring the density of the tobacco flowing in the feed channel adjacent the cutting knives. The measurements are taken either directly in the feed channel or proximately upstream thereof, and applied to a control system to regulate the tobacco input to the machine. Apparatus for effecting the density measurement may include radiation absorption measuring instruments.

Description

United States Patent [191 Marek et al.

[ 51 Jan. 9, 1973 {54] METHOD AND APPARATUS FOR REGULATING OUTPUT IN TOBACCO CUTTING MACHINES [75] Inventors: Josef Marek; Gunther Hayn, both of Vienna, Austria [73] Assignee: Austria Tabak Werke gesellschaft, Vienna, Austria [22] Filed: July 13, 1970 [21] Appl. No.: 54,357

Aktien- [30] Foreign Application Priority Data July 14, 1969 Austria...; ..A 6769/69 [52] U.S. Cl. ..83/l3, 241/223, 131/27,

83/72, 83/364, 83/403.1 [51] Int. Cl. ..A0ld 55/18 [58] Field of Search ..l46/1l9, 1, 95, 239

[56] References Cited UNITED STATES PATENTS 2,791,223 5/1957 Molins et a1. ..146/1 19 UX 2,832,352 4/1958 Powell ..l46/1 R UX 2,763,789 9/1956 Ohmart ..l46/95 UX 2,954,811 10/1960 l-lensgen et al 146/95 Primary ExaminerWillie G. Abercrombie Attorneyl-lubbe1l, Cohen & Stiefel 57 ABSTRACT The cut output of a tobacco cutting machine is regulated by measuring the density of the tobacco flowing in the feed channel adjacent the cutting knivesv The measurements are taken either directly in the feed channel or proximately upstream thereof, and applied to a control system to regulate the tobacco input to the machine. Apparatus for effecting the density measurement may include radiation absorption measuring instruments.

25 Claims, 4 Drawing Figures PATENTEDJAN 9 1975 SHEET 1 [IF 2 .N S KN E mE N T m AR EMW T T M NE ISN mm m PATENTEDJM 9l973 3,709,274

SHEET 2 or 2 I INVENTORS JOSEF MAREK GUNTHER HAYN BY Z , v I ATTORNEYS.

METHOD AND APPARATUS FOR REGULATING OUTPUT IN TOBACCO CUTTING MACHINES BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to tobacco cutting machines and more particularly to a method and apparatus for controlling the cut tobacco output of such machines.

2. Description of the Prior Art In the treatment of tobacco, the tobacco leaves are moistened and lieated to make them flexible before they are fed to the 61321666 cutting machine. The cut, moistened tobacco is heated and dried in drums to a desired moisture content usually by blowing warm air therethrough. In the further processing of the tobacco it is of particular importance that the desired moisture'content be precisely attained. However, the desired precision has been difficult to achieve due primarily to the fact that the cut output of the tobacco cutting machine may vary greatly, thereby resultingir? different quantities of tobacco with different moisture content being passed into the drying drum.

Many attempts have been made in the prior art to achieve cutting uniformity and moisture control. One such attempt involves so-called steep metering conveyors which are interposed between the tobacco cutting machine and the drying drum in order to assure a constant feed of tobacco to the drying drum. However, such devices require that portions of the incoming tobacco be stored in the conveyor device thereby producing undesirable accumulations of tobacco, which should be avoided.

Another approach has been to sense the varying moisture content and varying quantity of tobacco and thereby control the application of heat to the drying drum. However, it has never been possible by this method to achieve acceptable uniformity of moisture content.

It has also been attempted to weigh the cut tobacco at the outlet from the tobacco cutter by means of conveyor type weighers and thereby to control the speed of rotation of the rotating tobacco cutting head as a functionofthe weight measurement. Thismethod, mever, has proved costly and is particularly susceptible to undesirable disturbances.

An additional prior art approach involves an attempt to regulate the cutting capacity of the tobacco cutting machine. This type of control device has been utilized in tobacco cutting machines in which the tobacco is introduced from above into a generally vertical feed hopper, with control of the charging of the tobacco cutting machine being accomplished by attempting to maintain constant the height to which the hopper is filled. Such devices may utilize two photocells arranged one above the other, and upon a decrease of tobacco height in the hopper to below the lower photocell, additional tobacco is fed to the hopper until the height of the upper photocell is reached whereupon the tobacco feed is again interrupted. Alternatively, mechanical switches, which are actuated directly by the tobacco in the hopper and which operate by indicating and/or regulating the height to which the hopper is filled, have also been utilized in the prior art; However, it is apparent that merely maintaining the height of tobacco constant in the hopper is not fully effective to assure unifonnity of the tobacco output from the cutting machine. For example, if the tobacco has a high moisture content, a substantially higher density of tobacco will result within the cutting machine feed channel which feeds tobacco to the cutting knives, due to the fact that the individual tobacco leaves become softer and more easily compressed. Due to this high packing density in the feed channel, a larger quantity of tobacco maybe fed to the cutting knives thereby resulting in an increased rate of tobacco cut per unit time and a commensurate increase in the cutting capacity of the machine. Thus, despite the fact that the height of tobacco in the feed hopper is maintained constant,

there wilTstill be fiii iation in the cutting output of the tobacco cutting machine.

Accordingly, it is seen that deficiencies exist in prior art approaches to controlling the output uniformity of tobacco cutting machines particularly due to the fact that they lack the capability for accommodating variation in certain properties, especially moisture content, of the tobacco to be cut.

SUMMARY OF THE INVENTION In accordance with the present invention, control of the cut output of a tobacco cutting machine is obtained by measuring the density of the tobacco in the machine feed channel, or proximately upstream thereof, and utilizing said density measurement to regulate the input of tobacco to the machine.

Maintenance of uniformity in the cut output of a tobacco cutting machine may be controlled primarily by control of the density of the tobacco input due to the fact that all other parameters, such as cross-sectional area of the feed opening and number of cuts per unit time, will be dependent only upon the construction of the machine and the geometric arrangements thereof, and will involve constant factors. Accordingly, by sensing the density of the tobacco input, a control signal may be developed which can be utilized to affect the quantity of tobacco being fed to the cutting knives, totlierebfigulateflie unifofmity me cut output of the tobacco cutting machine. In some applications of the invention, the density of the stream of tobacco may be sensed at several points within the feed channel or proximately upstream thereof, with differences in the measured values being averaged to determine an average density value which may be utilized to control the tobacco input feed.

Accordingly, control of the input of the tobacco may be provided with continuous monitoring of tobacco density so that when the density measurement exceeds a permissible deviation from the desired value, charging of the input hopper may be affected by a control signal which has been derived from the density measurement in a manner to restore a desired value.

other mechanism for controlling a tobacco charging device, e.g., a conveyor belt, in order to control the tobacco input to the cutting machine.

In a preferred embodiment of the apparatus of the invention the density measuring device is a radiation absorption measuring instrument which comprises a source of radiation arranged on one side wall and a radiation detector arranged on the opposite side wall of a tobacco feed channel.

An alternative approach involving measurement of reflected radiation will permit utilization of a density measuring device comprising a radiation backscatter measuring instrument whereby the source of radiation and the radiation detector may be arranged on the same side wall of the feed channel.

With regard to thispreferred embodiment of the apparatus of the invention, it is advantageous to use as the source of radiation, a nuclear radiator, preferably a gamma radiator such as Co, Tm", or Cs Ba The designation Cs Ba indicates a radiator wherein the isotope cesium I37 emits gamma rays and upon disintegration forms the isotope barium 137 which also e n 1 i ts gamma rays, so that both ele ments of the radiator act jointly. l ";he radiation detec t or may suitably comprise an ionization chamber or a radiation-sensitive semiconductor.

-In a..preferred system for controlling the tobacco feed, the measured density signal is compared with a reference signal representing the desired density value, and a comparison signal is produced. This comparison back means, 1561mm"; tachometer generator, to stabilize the motor operation.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood by reference to the following detailed description of a preferred embodiment thereof taken in connection with the accompanying drawings wherein:

FIG. 1 is a sectional side elevation of a tobacco cutting machine showing a conveyor belt from which the tobacco cutting machine is charged;

FIG. 2 is a sectional front elevation through the feed channel of the machine of FIG. 1 showing the side walls and a radiation absorption measuring instrument mounted thereon;

FIG. 3 is a block diagram of a control system for intermittent charging; and

FIG. 4 is a block diagram ofa control system for continuous charging.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a tobacco cutting machine having a vertical feed hopper l, and a conveyor belt 2 driven by a motor'M whereby tobacco is introduced into feed hopper 1 from above.

Tobacco from the hopper 1 discharges into a feed channel 3 which, as best seen in FIG. 2, has fixed side walls 4 and a bottom conveyor 5 which is driven in a longitudinal direction by a pair of rollers 7. The conveyor 5 may be a conveyor belt, a feed chain, a ribbed belt or the like, and includes a fixed bottom plate 6 arranged therebelow to support the moving bottom conveyor 5 against the pressure of the stream of tobacco.

The feed hopper 1 includes a rear wall 8 pivotally supported at its upper end by a support 9 which is driven by a friction clutch motor 10 pivotally actuating the rear wall 8 to precompress the tobacco 21 introduced into the feed channel 3 and displace it in a direction towards the cutting knives.

The feed channel 3 includes an upper movable conveyor l l, which is similar to the bottom conveyor 5 and which is also formed of a conveyor belt, a feed chain or the like, driven by a pair of rollers 12.

The upper conveyor 11 and the bottom conveyor 5 both terminate at the outlet of feed channel 3 at approximately the same height, and form between them the outlet opening 13 of the feed channel 3. A rotating shaft 14 has mounted thereon a plurality of cutting knives 15 which are rotatively driven past the outlet opening 13 transversely to the feed channel 3. A pair of angle irons l6 defining the top and bottom of the outlet opening 13 are arranged forwardly of the upper and lower conveyors l1 and 5 in order to enhance the cutting action of the knives 15, with the upper angle iron 16 being connected to the conveyor 11 and movable therewith.

The conveyor 1 l is pivotally supported on a shaft 17 at a point upstream from the outlet opening 13 so that the front portion of the conveyor 11 adjacent the outlet opening 13 may yieldably compress the stream of tobacco passing thereunder. A counterweight 19 mounted to pivot about a shaft and arranged in the base of the tobacco cutting machine is connected as shown to the conveyor 11 in a manner whereby the conveyor 11 is rotatively biased about the pivotal support 17 to apply a uniform compressive force to the stream of tobacco.

In a machine of intermediate capacity, the width of the bottom conveyor 5 may, for example, be on the order of 400mm, and it may be driven at a linear speed of about 875 mm per minute. If the shaft 14 is rotated at about 250 rpm, there will be developed approximately 1,250 cuts per minute and the width of the cut tobacco will be generally between 0.6 and 0.8 mm. Thus, in such an intermediate capacity machine there will be obtained a cutting capacity of about 20 kg per minute with a density of cut tobacco of about 0.87 grams per cm. It should be noted that the density of the tobacco entering the feed channel 3 will be about 0.2 grams per cm, and that there is, therefore, obtained in excess of a fourfold compression of the tobacco during the travel through the feed channel 3 to the cutting knives 15.

In accordance with the present invention, one or more density measurements are effected prior to or within the feed channel 3. These measurements may be effected in any one of a number of appropriate manners all within the purview of the present invention.

One approach may involve weighing of the tobacco by mechanical means such as special conveyor belts or conveyor belt members connected to scales. Alternatively, pneumatic or hydraulic weighing devices may also be utilized rather than purely mechanical weighing. In such case, the density of the tobacco is determined by correlating the weight of the tobacco with the volume of the geometrical arrangement within which the weighed tobacco is contained, which would be known and constant. It will be apparent that by measuring variations in weight for a constant volume a density indication can be derived.

The density may also be determined electrically, by a measuring device arranged on the side walls 4 of the tobacco cutting machine with the measurement path being approximately transverse to the tobacco feed channel 3. The electrical measurements may be resistance measurements of a high-frequency current or capacitance measurements. In the case of capacitance measurements, the instantaneous value of the dielectric constant of the tobacco-water-air mixture between the side walls 4 of the feed channel 3 may be measured in a manner customary in the tobacco industry for measuring the moisture content of tobacco.

In the preferred embodiments of the present invention it is considered particularly simple and advantageous to determine the density measurement by measurement of absorption of electromagnetic rays or nuclear particles. In this connection, radioisotopes can be used to great advantage.

In accordance with the radiation absorption method of the preferred embodiment, a source of radiation Q is mounted upon the outer side of one side wall 4 of the feed channel 3 and a radiation detector D is arranged on the outer side of the opposite side wall 4 as shown in detail in FIG. 2. However, when the feed channel 3 of the tobacco cutting machine is not readily accessible from both sides the reflected radiation method may be employed wherein the source of radiation Q and the radiation detector D are fastened to the same side wall 4 of the feed channel 3 in a manner within the knowledge of those skilled in the art, with the measurement path being once again approximately transverse to the feed channel.

The density measurement can be effected at any desired point within the feed channel 3 or slightly upstream thereof so long as any changes in the density of the stream of tobacco from the point of measurement to downstream thereof are affected only by the geometric dimensions of the machine and not by any other influences. In this connection, it is to be noted that as the tobacco approaches the outlet 13, the density of the tobacco increases due to the pressure applied by the weight 19. Accordingly, the density measurement is probably best taken at a point in the stream of tobacco having a lower density, such as, for example, at the base of the feed hopper l where the tobacco is introduced into the feed channel 3. As previously indicated, the density ofthe stream of tobacco at this point is less than one-fourth the density at the outlet 13, namely about 0.2 grams per cm in the case of an intermediate capacity tobacco cutting machine.

Since the measurement devices are fastened directly to the side walls 4 of the feed channel 3, the length of the measurement path will be equal to the distance apart of the two side walls 4 which, in the case of parallel side walls 4, corresponds to the width of the movable bottom conveyor 5. In the example discussed herein, this distance is 400 mm.

In FIG. 2 there is shown a sectional view of the density measuring instrument of the preferred embodiment which includes the radiation source Q arranged on the left side wall 4 and the radiation detector D which comprises an ionization chamber, arranged on the right side wall 4.

The source of radiation Q comprises a centrally located rotatable aluminum cylinder 22 which forms the mount for the radiation source and contains at its center a radiator 23, which may comprise a radioactive preparation such as a C0 gamma radiator. Radiation emerges from the cylinder 22 through a radial bore hole or a radial slot 24 which extends to the center of cylinder 22 and to the radiator 23. This slot or bore hole 24 is closed by a radiation window 25 which may be formed of chrome steel. The cylinder is arranged for rotation by an electric motor, (not shown) so that when the apparatus is not in use, the radiation window 25 can be directed out of the depicted position away from the stream of tobacco and towards appropriate screening which may comprise a lead jacket 26 having the radiation window 25 mounted therein. The cylinder 22 is supported in a supporting body 27 which may also consist of aluminum and which is fastened, for example by screws 28, to the outside of the side wall 4 of the feed channel 3. The supporting body 27 is open towards the feed channel 3 and extends through the side wall 4 of the feed channel 3, but terminates flush with the inner side thereof so as not to create any resistance to the flow of the stream of tobacco. The opening of the supporting body 27 on the inside of feed channel 3 is closed by a radiation window 29, which may also be formed of chrome steel. The supporting body 27, is in turn, surrounded on the outer surface thereof by a lead shielding 30.

In the operating position, i.e., with the outlet slot 24 of the cylinder 22 directed towards the feed channel 3,

the radiation passes from the radiator 23 through thetwo

radiation windows

25 and 29 into the stream of tobacco. The radiation detector D is mounted on the opposite side of the feed channel 3 on the outside of the second side wall 4 of the feed channel 3 in alignment with the radiation source Q. The radiation detector D comprises an ionization chamber 31 which is of a generally customary type, mounted within a supporting body 32 which may be formed of aluminum. The supporting body 32 is fastened by screws 28 or the like to the side wall 4 and extends therethrough to the feed channel 3, terminating flush with the inside of the side wall 4. On the side thereof towards feed channel 3, the supporting body 32 has an opening which is closed in the plane of the inner face of the side wall by a radiation window 33 which may be formed of chrome steel. The opening for the entrance of the rays into the ionization chamber 31 is closed by a chamber window 34, which may be suitably formed of bronze and which is curved towards the feed channel 3 due to the fact that the ionization chamber 31 is under pressure. The two poles of the ionization chamber 31 are connected with an electrometer preamplifier 35 which is arranged on the rear of the ionization chamber 31 and gives off an amplified measurement signal. Extending from the electrometer preamplifier 35 is a line 36 which is connected to the control device, e.g., for the motor M of conveyor 2, of the charging apparatus for the tobacco cutting machine.

It should be understood that the arrahgement of the radiation source Q need not correspond in structural detail to the foregoing description and may comprise any appropriate known arrangement. A variety of radiation generating devices, including means producing the bremsstrahlung of different beta rays or means for producing X-rays, may be appropriately considered for use as the source of radiation Q. However, factors related to the specific tobacco cutting machine must be taken into consideration. One such factor is average density of the tobacco occurring at the point at which a measurement is to be taken. Since not all sources of radiation enumerated are suitable for all tobacco densities which occur, a selection must be made in each case.

Alpha radiators are better suited for very low densities since the scattering which occurs is very great and many side phenomena may arise. Beta radiators, which have a depth of penetration which is greater than that of the alpha radiators, are better adapted for use in smaller capacity tobacco cutting machines in which the density of the stream of tobacco to be measured is not too high, i.e., not higher than about 0.5 to 1 gram per cm". Among beta radiators, the radioisotopes, thallium 204, krypton 85, and strontium 90 yttrium 90 are considered appropriate. In this connection it is to be borne in mind that, since density measurement will depend -upon radiation absorption, the most accurate measurements are to be expected when about one-half of the radiation is absorbed.

lf higher densities occur in the stream of tobacco at the measurement point, as will occur in the case of intermediate and larger capacity tobacco cutting machines, then the use of gamma radiators or of bremsstrahlungs of beta radiators is more favorable. This would also be the case when the measurement point is not located upstream of the feed channel 3 but lies within it in the vicinity of the outlet opening 13. ln such cases, appropriate radiation sources would be the gamma radiators thulium 170, cesium 137 barium l3? and cobalt 60. As bremsstrahlung there can be used the bremsstrahlung of the beta radiator strontium 90 yttrium 90, which has been previously mentioned. These radiators are favored because for intermediate capacity tobacco cutting machines, the stream of tobacco.at the upstream end of the feedc'hannei 3, at which a density measurement could be effected, has a density of about 8 grams per cm The selection of the radiators is, of course, not dependent merely upon the energy and depth of penetration of the emitted radiation but also upon their suitability for industrial use. More particularly, requirements as to the half-life of the material must be satisfied, since sources of radiation of too short a halflife will have to be replaced too frequently and are therefore too expensive and impractical.

Appropriate known radiation detectors may comprise ionization chambers, Geiger counter tubes, scintillation counters or radiation-sensitive semiconductor elements. Since it would be favorable if the measurement signals could be processed as analogs, and since a certain amount of averaging occurs in effecting a measurement, ionization chambers or radiation-sensitive semiconductor elements may be preferred.

If the density measurement is to be effected by a reflected radiation technique on the basis of backscatter radiation, then the radiation detector D and the source of radiation O, which may in principle be of a similar configuration as those shown in F lG. 2, may be arranged on the same side wall 4 of the feed channel 3. In this connection, it is merely necessary to take precautions in a customary manner to provide suitable shielding of the direction radiation which may occur between the source Q and the radiation detector An additional factor to be considered relates to the locations at which density measurements may be taken without departing from the purview of the present invention. For example, tobacco fed into the feed channel 3 need not necessarily come from a vertical feed hopper l but may be directly introduced through other appropriate sources, within the knowledge of those skilled in the art. Accordingly, the term feed channel, particularly as used in the claims, is not intended as being limited to the specific structure described but should be understood to include any point in the stream of tobacco flowing to the cutting knives at which meaningful density measurements can be taken for the purposes set forth. The appropriateness of the locations selected will depend upon whether there can occur downstream thereof density variation which could interfere with the effectiveness of the invention.

Utilizing the measurement signal of the density measuring device, the charging conveyor belt 2 of the tobacco cutting machine may be controlled by means of an appropriate control arrangement. As shown in FIG. 1, the conveyor 2 is driven by a motor M, and control thereof can be effected in any known manner, for example pneumatically, hydraulically or electrically, by one skilled in the art. Examples of electrical controls are shown in the form of block diagrams in FlGS. 3 and 4.

FIG. 3 is a schematic representation of a system for intermittent charging of a tobacco cutting machine which operates to energize the motor M of the charging device thereby adding tobacco when the density drops below a predetermined value. When a predetermined maximum value has been reached, the motor M is again shut off. In the operation of the circuit of FIG. 3, a density measurement signal, which is generated by a density measuring device comprising the source of radiation Q and the ionization chamber I, is compared with a reference signal which represents a desired value density signal obtained, for example, from apparatus which may comprise a source of radiation designated 0,. and an ionization chamber l,.. Into the radiation path of this second reference-signal-generating instrument there is inserted a comparison absorber V, which may be wedged shaped and adjustable vertically, for example, by means of a spindle 40, 'so that the comparison absorber V, can be inserted to a desired thickness into the measurement path to variably control the quantity of radiation absorbed. The ionization chamber I of the density measuring apparatus generates the actual density measurement signal, while the ionization chamber l of the reference-signalgenerating device gives off a desired value density signal. The two signals are amplified in amplifiers E and E,. and are fed to a comparator K where they are compared. The comparator gives off a comparison signal which is proportional to the difference between the two values and which is fed via a trigger circuit 2, for example, a Schmitt trigger, to a switch SW which controls the motor M of the tobacco charging device. The trigger circuit 2 may be a bistable device which is driven from one stable state to the other, depending upon the level of the comparison signal from the comparator K, thereby driving the switch SW between an ON and an OFF position. This will turn the motor M ON and OFF thereby to intermittently stop and start tobacco input feed.

In FIG. 4 there is shown a block diagram of an exemplary system for controlling charging of a continuously charged tobacco cutting machine. In this embodiment the density measurement signal is once again taken from the ionization chamber 1 of the density measuring device and fed through an amplifier E to a comparator K. The reference signal is in this case produced, for example, electrically by a potentiometer S and is amplified in an amplifier V and then fed to a comparator K. The comparison signal given off by the comparator K is again proportional to the difference between the two values and is fed to a servomechanism, including a servomotor SM which may be connected to drive the tobacco input charging device. The servomechanism includes a controller P] which is connected to the control stage A of motor SM whereby the operating speed of the motor may be continuously controlled to regulate the rate at which tobacco is fed to the cutting machine input hopper. In the operation of the control system of FIG. 4, tobacco density is continuously monitored with the input quantity being increased or decreased in response to the sensed density of the tobacco flowing through the feed channel. The comparison signal generated by comparator K is applied as an input to the controller PJ whose output is applied as a motor control signal. Stability of the motor control is obtained by a feedback loop which comprises a tachometer-generator G which is connected to the motor SM and which provides a feedback signal to the controller PJ. As the density of tobacco in the feed channel 3 varies above or below a predetermined level, the speed of the motor SM is increased or decreased to appropriately adjust the quantity of tobacco input flow.

It is to be understood that the above described embodiments of the invention is merely illustrative of the principles thereof and numerous modifications and embodiments of the invention may be derived within the spirit and scope thereof.

What is claimed is:

1. In a method for regulating the cut output of a tobacco cutting machine, said machine comprising means for providing flow of tobacco input thereto, tobacco cutting means, and a feed channel adjacent said cutting means in flow relationship between said cutting means and said tobacco input means, the steps comprising measuring the density of tobacco within said feed channel irrespective of the height of said tobacco, generating a control signal representative of said density measurement, and applying said control signal to said tobacco input means for controlling said tobacco input flow in response to said density measurement.

2. The method according to claim 1 wherein the density of the tobacco is sensed at a plurality of points, and

wherein the density values sensed at said points are averaged to generate said control signal.

3. The method according to claim 1 wherein said tobacco density is sensed upstream from said feed channel and proximate thereto.

4. The method according to claim 1 including the steps of generating a reference density signal, comparing said reference signal with a signal representative of the actual sensed density of the tobacco stream, and generating said control signal as representative of said comparison.

5. The method according to claim 1 wherein the quantity of cut tobacco produced by said cutting machine is maintained generally constant.

6. The method according to claim 1 wherein said tobacco input flow is intermittently stopped and started in response to said density measurement.

7. The method according to claim 1 wherein said tobacco input flow is continuously maintained with the rate of flow being raised and lowered in response to said density measurement.

8. Apparatus for regulating the cut output of a tobacco cutting machine, said cutting machine comprising means for providing tobacco input flow thereto, tobacco cutting means, and a feed channel defined between side walls and located adjacent said cutting means in flow relationship between said cutting means and said tobacco input means, said regulating apparatus comprising:

density measuring means mounted upon said feed channel side walls for generating a signal representative of the density of tobacco flowing through said feed channel irrespective of the height of said tobacco in the feed channel; and

control means coupled between said density measuring means and said tobacco input means receiving said representative density signal for regulating said tobacco input flow in response to the measured density of tobacco flowing through said feed channel 9. Apparatus according to claim 8 wherein said density measuring means are mounted in a position proximately upstream of said feed channel.

10. Apparatus according to claim 8 wherein said density measuring means are mounted on opposite sides of said feed channel to sense the density of flowing tobacco in a direction transversely of said flow.

11. Apparatus according to claim 8 wherein said density measuring means comprise radiation absorption measuring means.

12. Apparatus according to claim 11 wherein said radiation absorption measuring means comprise a nuclear radiation source and a nuclear radiation detector.

13. Apparatus according to claim 12 wherein said nuclear radiation source is mounted upon one of said feed channel side walls with said radiation detector being mounted upon an opposed side wall.

14. Apparatus according to claim 11 wherein said density measuring means comprise a radiation backscatter instrument having a radiation source and a radiation detector both mounted upon the same one of said feed channel side walls.

15. Apparatus according to claim 12 wherein said nuclear radiation source comprises a gamma ray source.

sity signal and said reference density signal and generating a comparison signal proportional to the difference therebetween; and means for applying said comparison signal to said tobacco input means to regulate tobacco input flow in response to said comparison signal. 22. Apparatus according to claim 21 wherein said reference density signal is generated by nuclear radiation means.

23. Apparatus according to claim 21 wherein said reference density signal is generated by electrical means.

24. Apparatus according to claim 21 wherein said comparison signal applying means comprise means for intermittently starting and stopping said tobacco input flow.

25. Apparatus according to claim 21 wherein said tobacco input means is operated to maintain a continuous flow of tobacco, said comparison signal applying means comprising means for increasing and decreasing the rate of tobacco input flow.

Claims

2. The method according to claim 1 wherein the density of the tobacco is sensed at a plurality of points, and wherein the density values sensed at said points are averaged to generate said control signal.

8. Apparatus for regulating the cut output of a tobacco cutting machine, said cutting machine comprising means for providing tobacco input flow thereto, tobacco cutting means, and a feed channel defined between side walls and located adjacent said cutting means in flow relationship between said cutting means and said tobacco input means, said regulating apparatus comprising: density measuring means mounted upon said feed channel side walls for generating a signal representative of the density of tobacco flowing through said feed channel irrespective of the height of said tobacco in the feed channel; and control means coupled between said density measuring means and said tobacco input means receiving said representative density signal for regulating said tobacco input flow in response to the measured density of tobacco flowing through said feed channel

9. Apparatus according to claim 8 wherein said density measuring means are mounted in a position proximately upstream of said feed channel.

16. Apparatus according to claim 12 wherein said nuclear radiation source comprises Co60.

17. Apparatus according to claim 12 wherein said nuclear radiation source comprises Tm170.

18. Apparatus according to claim 12 wherein said nuclear radiation source comprises Cs137 + Ba137.

19. Apparatus according to claim 12 wherein said radiation detector comprises on ionization chamber.

20. Apparatus according to claim 12 wherein said radiation detector comprises a radiation-sensitive semiconductor.

21. Apparatus according to claim 8 wherein said control means comprise: means for generating a reference density signal; a comparator for comparing said representative density signal and said reference density signal and generating a comparison signal proportional to the difference therebetween; and means for applying said comparison signal to said tobacco input means to regulate tobacco input flow in response to said comparison signal.

22. Apparatus according to claim 21 wherein said reference density signal is generated by nuclear radiation means.