US2509488A - Tobacco stemming - Google Patents

Description

2 Sheets-Sheet 1 n. 'lull L. N. DIBRELL, JR

TOBACCO STEMMING May 30, 1950 Filed Dec. 1o, 1947 May 30, 1950 L. N. DIBRELL, JR 2,509,488

TOBACCO STEMMING Filed Deo. 10, 1947 2 Sheets-Sheet 2 mmm/l H im Il /llllllllll Patented May 30, 1950 UNITED STATES lA'i'iENT QFFICE TOBACCO STEMMING Louis N. Dibrell, J r., Danville, Va. Application` December 10, 1947, Serial No. 790,835

(Gl. ISI- 130) 15 Claims. 1

The present invention relates to a tobacco stemming` mahne. More particularly, the invention concerned with a` machine of the type in which` a conveyor serves to. present` the butt ends of the stems of successive leaves to the bite of a pair of co-acting, stem-drawing rolls, which operate to pull the. stems from the blade portions of the` leaves, the blade, portions being securely held. by the conveyor.

A number of` devices of this nature, have been proposed. A few of. these have not been. Sufciently ecient in operation to meet with commercial success. On. the other hand, those machines which have proved capable of ecient operation have generally been characterized by complexity of design and a resulting high cost of manufacture and' maintenance,V thus precluding utilization by certain tobacco processing plants.

The primary object of my invention is` the provision` of a simple,` inexpensive tobacco stem.- ming machine designed to meet the requirements of tobacco stemming plants. A machine of this nature must also be adapted for ease of operation, repaizg, and maintenance and atr the same time must yet be capable of high efficiency in its stemming operation.

rl'he principal feature of my invention is the design of the stem drawing roll assembly. The rolls of the invention have been especially designed to exert a positive gripping and pulling action, on leaf stems while simultaneously producing efcient receiving, engaging or threadingin, and transverse feeding motions.

It is known to provide both rolls.` of a co-acting pair with conical ends in order to give an enlarged stem, receiving area. It has also been taught that rolls provided` with spiral guiding surfaces, in the Vicinity of their receiving ends will promote transverse stem movement along the axis of the rolls to the position of the stem drawing surfaces o the rolls. However, so far as is known to me, the drawing operation has been practically universally dependent upon friction (between stem and rolls) induced by the pres,- sure of smooth or slightly roughened roll surfaces. While this principle meets with success in some machines, it is entirely undependable in machines in which the rolls do not attain high surface velocities (that is, rotation of the order of l6002400 revolutions per minute).

I have found that a type of stem drawing roll assembly wherein the rolls may be generally described as screw-threaded, is capable of highly erlicient stemming if the threads of the adjacent rolls are made to inter-mesh. A roll assembly of this nature is well-suited for stem drawing in machines which operate at relatively low speeds, that is, of the order of 4004000 revolutions per minute.

The invention is illustrated in the drawllss in which:

Fig. 1 is a plan view of a stemming machine employing the roll design of the invention,

Fig. 2 is a side elevation of the machine,

Fig. 3 is an end elevation,

Fig. 4 is an enlarged side elevation of a portion of a pair of rolls in` operative co-acting position, the rolls being in part cut away to show a vertical section through their adjacent surfaces,

Fig. 5 is a side elevationof a modiiicationl of the roll assembly of Figs. 1 4, the rolls being mounted on converging axes,

Fig. 6 is a side elevation of another modification of the roll assembly, each roll being tapered over its entire length,

Fig. 7 is a side elevation of a further modification of the roll assembly wherein each roll is cylindrical over its entire length, the rolls being mounted on converging axes,I

Fig. 8 is a side elevation of still another modiiication of the roll assembly wherein each roll has a cylindrical portion and a relatively slightly tapering conical portion,

Fig. 9 is a side elevation of another roll assembly of modified form wherein one roll is entirely cylindrical and the second roll is tapered over its entire length,

Fig. 10 is a fragmentary axial section through an intermeshing portion of a pair of rolls having a ridge and groove type of threading` as provided on non-meshing portions of the rolls of` Figs. 1-4,

Fig. 11 is a fragmentary axial section, through a pair of rolls having a land and groove type threadl over both non-meshing and intermeshing portions,

Fig. l2 is a fragmentary axial section, in part in elevation, through the intermeshing portion of a pair oflrolls having a land-groove type thread wherein the lands are roughened or knurled, and

Fig. 1'3 is a fragmentary axial section through an intermeshing portion of a pair of rolls having a land-groove type thread with rounded grooves.

With reference to the drawings, I is an endless conveyor supported on two pulley wheels 2 and 3. TheV conveyor and pulleys` may be of any practical form, and their nature is of no particular importance to the invention. In the illustrations, the conveyor is shown as a belt provided with card teeth 4 in customary fashion and mounted on chains l2. The pulley wheels are provided at their ends with sprockets to accommodate the chains.

A second endless conveyor 5, also provided with card teeth, is positioned above the conveyor l on sprocket ended pulleys 5 and 'i so that tobacco leaves placed on the conveyor i will be engaged by the teeth of both conveyors. The spacing oi the two conveyors may be such that there will be an intermeshing of their card teeth on the operative flight; however, in the preferred arrangement the upper conveyor is sufciently spaced from the lower conveyor that the tips of the teeth of one are in close proximity to and barely clear of the tips of the teeth of the other. The pulley wheels 3 and are identical and are respectively mounted on shafts 8 and E3 on which are keyed identical intermeshing gears lil and il respectively.

The shaft 8 receives power from a driving unit or motor I4 through chain drive i5 and a driving sprocket i8. It is obvious that the driving arrangement will result in equal speeds of the conveyors since the identically sized gears l@ and Il must rotate at the same speed under the driving influence of the drive mechanism i6., l5, and I6.

The shaft 8 is provided with a bevel gear I8 which co-operates with a bevel gear i9 to transmit power to a lower stem-drawing roll 2E! mounted on shaft 2i. Also mounted on shaft 2| is a pinion gear 22 which intermeshes with an identical pinion gear 22' positioned directly above it and keyed to a shaft 23 on which is mounted upper stem-drawing roll 2t.

The roll shafts 2l and 23 are journalled at each end in supporting frames 25, 25'; the upper roll 24 being yieldingly forced toward the lower roller 20 by the pressure of adjustable spring retaining means 26 and 2l. A portion of the frame 25 on the side of the receiving ends of the rolls is offset as at 28 to provide for clearance of the leaf stems,

The rolls 20 and 24 are conical (tapered) for approximately 1/3 of their length along the portion indicated by arrows at 29 and are generally cylindrical throughout the remaining portion 30. The entire surface area of each roll is provided with -a screw-threaded type of configuration comprising (Fig. 4) grooves 3l and ridges or threads i3 which have their origins at the terminus or small end of the roll. These grooves and ridges are continuous from their origins to the opposite end of the roll, being therefore, spiral in conformity with the surface of the tapered portion of each roll and helical in conformity with the surface of the cylindrical portion.

The grooves 3'! are V-shaped in section throughout, but each ridge, which otherwise is also V-shaped, has its edge or top portion sheared oi or out away throughout the stem-gripping portion of the roll to form a flat-topped land 32. Thus, while a normal ridge I3 has a section identical with that of a cone, an altered ridge or land along the cylindrical portion of the roll has a Afiat-topped section identical with that of a truncated cone.

Y Therefore, when disposed in intermeshing relationship adjacent each other (operative position), the lands 32 along the cylindrical and a -part of the tapered portion of each roll extend down into the co-acting grooves 3l of the opposite roll. This arrangement affords at once both positive gripping and positive guiding actions to the tobacco stems fed between the rolls. The grooves serve to guide the stems both longitudinally and transversely as the rolls turn together, and the co-acting lands serve to retain the stems in position in the grooves. The configuration of the co-acting lands and grooves assures that the stems will not be jammed or cut and mobility of the stems in the bite of the rolls will not be hindered. On the other hand, however, the combination gives sufficient pinching action to produce traction and promote longitudinal steindrawing movement of the stems.

Stem butt ends will ordinarily be engaged along the tapered portions near the point of convergence of the tapered portions of the rolls and the drawing operation continued and completed along the cylindrical portions of the rolls, The

stem-engaging portion of each roll is normally referred to as the stem-gripping or stem-drawing portion, and the small end of the conical portion is termed the stem-receiving portion. It is found in actual practice that depending on the conformity and spacing of the rolls, stem-drawing may take place to a substantial degree along the portion of the tapered part of the rolls which is immediately adjacent the cylindrical portion. The point along the rolls where gripping of the stem rst occurs varies with stem size and when, for instance, a large stem has its butt end engaged in the bite of the threads well out along the tapered portion, the drawing operation is obviously begun at that time, and convergence of the vopposed roll surfaces compensates for taper of the tobacco stem whereby grip of the rolls is maintained on the stem. 'Ihat is to say, as the stem is drawn through the rolls the diameter of that portion of the stem engaged by the rolls becomes increasingly smaller because of the taper of the stem and the relative movement of the stem from its large to its small end transverse of the rolls, but at the same time, the stem is threaded along the longitudinal Iaxes of the rolls whereby the convergence of the roll surfaces approximates the extent of stem taper so that there is substantially continuous gripping of the stem by the rolls. In other words, the degree of the convergence of the tapered portions of the rolls is such that despite the taper of a stem and its movement both transversely and longitudinally of the opposed faces of these portions, the stem is at all times substantially in contact with both of said opposed faces.

Therefore, in some instances, stem-drawing will be accomplished substantially or entirely before a stem reaches the cylindrical surface of the rolls. Accordingly, it is obvious that the portion of a roll which functions to grip and draw stems is determined by the shape, threading and relative positioning of the rolls as well as stern size. In the form of the invention illustrated in Figs. 1 4, which has proved very practical, the area of each roll which serves in gripping and drawing stems appears to comprise a portion of the cylindrical surface plus a portion of the immediately adjacent tapered surf-ace. In this form, however, the rolls have their axes substantially parallel, and it is obvious that if the rolls be mounted with their axes in converging planes as illustrated in Fig. 5 (wherein 20d and 24a denote lower and upper rolls respectively and 29a indicates tapered portions), the position along the rolls at which stem-drawing occurs would be changed.

Thus, it follows that stem-drawing may take place along either the tapered portions entirely or the cylindrical portions entirely. In the former case, it is possible to dispense with the cylindrical portions of the rolls (Fig. 6, wherein '20h and 24h denote lower and upper rolls respectively)` or it may be desirable to` prepareA the entire rolls; in cylindrical form and mount them inA converging planes (Fig. 7,`wherein Zoo and 2de respectively denote lower and upper rolls)` so` that one end of the roll assembly will serve for stem-receiving and guiding and the opposite end will be closely intermeshed.

The various forms of rolls and roll assemblies shown in the drawings are merely modifications of the invention used for the purpose of illustration and are not indicative of any limitation in the apparatus. The rolls may be tapered for one-halfoftheir total length, and they willprove efficient if tapered over an even greater portion, say for twothirds of their length with the remaining one-third being cylindrical. Iir thezlatter case (Fig. 3, wherein lower and upper rolls, 20d and" Edd, respectively, have tapered portions 29h) depending on the overall' dimensions` of the rolls, the taper may be of such gradual degree that intermeshing of the lands and grooves will occur over a large part of the tapered portion with the possible result that all stem-drawing will take' place along the conical or tapered portion before. the stems ever reach the cylindrical portion. arrangement` may be preferable in many cases since by means of it the eiect of roll taper in compensating for stem taper will be accentuated.

Thus it is evident that roll form may be varied within a wide range of designs inclusive of those mcdil'lcations in which (c) both rolls are tapered throughout their length, (bi) both rolls are cylindrical in their entirety, and (ci) one roll of the pair is tapered atleast in part while its co-acting roll is entirely cylindrical (lig. 9, 2te and-` 24e respectively being rolls of a coacting pair), the only limiting factors in each case being that (c) both; rolls are screw-threaded and (b) the threads of the coasting rolls are made to interrnesh over a substantial portion oi" the rolls.

The design and assembly of the rolls removes any restriction otherwise required in operating speeds. Since the rolls are not dependent for stein-drawing upon the production of oertain minimum speeds to create a surface friction greater than a particular minimum value, the e'm :ency of the stemming operation is wholly ndent of the operating speed of the stemdi.M .ing rolls, therein lies the essence of the invention. cient stemming has resulted from varying speeds up to 9Go revolutions per minute.

The noinabove described roll surface has been found most practical, but itis within the scope of the invention to have the ridges and grooves of any desired shape and; form wherein they will intermesh to produce guiding" pocket or cut into which protrudes an oppositely disposed retaining surface, the combination and :xc-operation of the two elements serving to give a traction inducing pinch e'eot.

it may sometimes be desirable, for instance, to leave the sharp-edged` ridges or threads along the stezmdrawing portion of the rolls as illustreated in Fig. 1G, the ridges 'seing denoted by the nur and the grooves by 3 la. The sharpridiges or the lands may be provided with tr reverse cuts or notches or otherwise roughened as illustrated in l2, lands being denoted by 32h, grooves by and knurling by fil. rihe term screw-threaded as used in this disclosure is intended to generally descriptive of any roll surface having a form in accordance with the general speciiications listed above. The threads may vary in pitch, depth, width, and in cross-l sectional shape. The ridges may, for instance; be formed with square edges which intermesh with grooves having rounded, rather than V-shaped, bottoms asillustrated in Fig. 13 where,- in square edged ridges (lands)1 are denoted by 32o' and 48 denotes rounded grooves.

The width of the grooves should be suilicient to accommodate the largest size of stems to be operatedl upon` and deep enough to retain the stems, otherwise, the angle formed by the sides of the threads and grooves may vary, preferably within the range of 10 to 90. Further, the pitch of the threads and grooves may vary within the range` 45 to a fraction of l as long as the threads of a mounted roll assembly are not disposed at an angle of greater than about 30 from the stems as presented to the rolls.

The degree to which the rolls intermesh is made adjustable by the springwetaining means 2S and 2-1, and the` proper pressure between the rolls for a particular operation is determined by the particular type and moisture content of the tobacco being processed, it being only necessary to try several settings in order to determine the spacing for optimum conditions of operation with any particular lot of tobacco. It is obvious that the nature and strength ci springs 33 utilized in the retaining means 25 and 2l will also dictate to some extent the proper setting oi the retainers.

As pointed out above, it is within the scope oi the invention that the size of the rolls, the depth of the grooves, or the angle oi inciden-ce of the threading be varied. However, it has been determined that efficient rolls may have an overall length of approximately lli inches with a maX- imum diameter of about 3 inches. When pre pared in this size, the taper ends at about 5 inches from the receiving end with the remaining 9 inches of the roll being cylindrical and the diameter of; the small or receiving end being 2 inches. Suitable thread size is 1/2 inch, the threads being cut to a vertical depth of 1%; of an inch from the surface of the lands which are approximately 1/8 of an inch in width.

The threading over the tapered stem-receiving portion` 29 of each roll may comprise, instead of grooves 3l and ridges lf3 as shown in Figs. 1, 2 and 4, the same groove and land arrangement as is formed in the surface of the cylindrical portion, as illustrated in Fig. li wherein grooves 3io and lands 32a are continuous over both the tapered and cylindrical portions. However, since the function of these small portions of the two rolls is to form between them a stem receiving portion, it is generally preferable and more conducive to proper threadingeinA and guiding of the. stems. that the ridges be `J-shaped to give maximum groove depth.

It is to be understood that the surface configuration of the stem-receiving portion of the rolls is not important to the present invention except in the respect that some stem-receiving means be provided for proper guiding and threading in of the` stems to the nipping or sterndrawng surfaces along the bite of the drawing rolls. Thus, any one of a number of known designs may prove satisfactory for the surface of the stem-receiving portion of the rolls.

The lower conveyor l is given additional support along the portion on which the stemming operation takes place by a table 35, and it is prei.- erable when a chain drive is employed for the conveyor that the `chain or chains ride in grooves along the table, whereby the conveyor is secured against transverse sway and warping. If so desired, the upper conveyor may be steadied by a like retaining surface 355 in order that the ends of the card teeth of the two conveyors be forced to remain in close proximity while the stemming operation is in progress.

In operation, tobacco leaves are fed from a chute or conveyor (not shown) onto the lower conveyor l in such manner that each leaf has its longitudinal axis (stem) perpendicular to the longitudinal axis of the conveyor with the butt end of each stem extending beyond the edge of the conveyor` adjacent the stem-drawing roller assembly. The leaves are engaged by the card teeth and move with the conveyor in the direction indicated by the arrows (Figs. l and 2). At the point 3l, the card teeth of the upper conveyor converge on the leaves so that while the leaves are undergoing the stemming operation, they are held in position on the card teeth of the lower conveyor by the card teeth of the upper conveyor.

At position 33 the butt ends of the leaf stems are presented in the opening between the tapered ends of the stem-drawing rolls. At or before the stems reach position 39, the stems are threaded into one of the grooves 3! between the ridges or threads I3. From the vicinity of the point 39 the stems are securely retained within the grooves 3| by the co-acting lands 32.

The rolls and 24 being geared to turn in opposite directions as indicated by the arrows, (Fig. 3) begin (in the vicinity of 3S) pulling the stems from the blade portions retained by the card teeth, the stems finally being pulled free of the blade portion pass through the bite of the rolls and fall from the rolls on the side opposite the conveyor belts.

While the stem drawing operation is in progress, the drawing rolls are providing movement of the stems transverse of the long axis of the stems, i. e. in a direction parallel to the long axis of the rolls. This, of course, is the obvious ren sult of the conformation of the lands and grooves, and it is desirable that the transmission of power to the rolls be so related to the conveyor drive and to the angle of incidence of the threading on the roll surface that the transverse moven ment of the stems (e. g, in the direction paralleling the longitudinal axes of the rolls) be at the same rate as the movement of the conveyor belts. The stem. and leaf portions thus have relative longitudinal movement, but have no relative movement transversely and the preciseness of the stemming operation is enhanced.

The stemmed leaves or blade portions continue their travel with the conveyors until they reach a point approximately at ill where they may be removed by any desirable type of mechanism.

As noted above, dimensions of the stem drawing rolls may be varied. It is also to be noted that roll diameter will to some extent determine the proper relative position of the conveyor with respect to the rolls (point of tangency of the rolls) and will thus also determine to some extent the portion of stem length along which stripping of the blade will be achieved. Therefore, roll size should be selected in accordance with these factors.

However, it is obvious that the stem drawing rolls are suited for employment in machines of widely Varying type, and it is recognized that they will prove useful with conveyors of other nature than that herein disclosed. The roll assembly is adapted for use with any conveyor which will supply proper gripping of the leaves while serving to accomplish proper presentation to and movement of the leaves with respect to the rolls. Likewise, it is not intended that the power and driving arrangement be a limitation to the use of the drawing rolls of the invention, as it is obvious that any type of prime mover and power transmission system may be employed so long as proper relative movement of the essential elements be obtained.

It is to be noted that the simplicity and design of the machine are conducive to ease of disassembly and assembly, and it is a feature of the invention that the machine is thus adapted to be moved with facility from one plant to another as required by the seasonal activity in various tobacco producing regions.

I claim:

1. In a tobacco stemming machine, a pair of co-acting stem drawing rolls having cooperating screw-threaded surface portions which are at least in part intermeshing, and means adjacent said rolls for holding the blade portion of a tobacco leaf while said rolls draw the stem of said leaf.

2. In a tobacco stemming machine, a pair of co-acting rolls having opposing cooperating screw-threaded surfaces, the threads of said rolls being in intermeshing relationship along at least a portion of the opposing surfaces of said rolls', and at least a part of the intermeshing surface portion of each roll being generally cylindrical, and means adjacent said rolls for holding the blade portion of a tobacco leaf While said rolls draw the stem of said leaf.

3. An assembly as dened in claim 2 wherein the screw threads on the cylindrical intermeshing surface portion of at least one roll comprise lands and grooves.

4. In a tobacco stemming machine, a pair of co-acting rolls having generally cylindrical body portions and adjacent tapered stem-receiving portions coaxial therewith, said rolls being provided with cooperating surfaces having oppositely pitched screw threads which are in intermeshing relationship along substantial portions of the adjacent faces of said rolls, and means adjacent said rolls for holding the blade portion of a tobacco leaf while said rolls draw the stem of said leaf.

5. An assembly as dened in claim 4 wherein the intermeshing portions of the surfaces of said rolls are at least in part along said cylindrical body portions of said rolls.

6. An assembly as dened in `claim 4 wherein the screw threads of each of said rolls extend continuously over at least a part of the tapered stem-receiving portion and at least a part of the cylindrical body portion thereof.

7. An assembly as defined in claim 6 wherein the intermeshing part of the surface portion of each of said rolls includes -at least a part of the surface on the cylindrical body portion thereof.

8. In a tobacco stemming machine, a pair of leo-acting stem-drawing rollshaving stem-receiving portions and stem-drawing portions and provided with oppositely pitched cooperating screwthreaded surfaces adapted to advance tobacco stems along the axes of said rolls, the screwthreaded surfaces of said rolls being in intermeshing relationship along the stem-drawing portions of the rolls, and means adjacent said rolls for holding the blade portion of a tobacco leaf while said rolls draw the stem of said leaf.

9. In a tobacco stemming machine, a pair of co-acting rolls having co-acting tapered end portions and surfaces provided with cooperating screw threads, said threads being in intermes'hing relationship along at least a portion of said surfaces, said portion including at least a part of said tapered end portions, and means adjacent said rolls for holding the blade portion of a tobacco lea-f while said rolls draw the stem of said leaf.

10. An assembly as denecl in claim 9 wherein the screw threads on the tapered intermeshing portion of at least one roll comprise ridges and grooves.

11. In a tobacco stemming machine, a pair of converging adjacent co-acting screw-threaded rolls, the threads of the rolls being in interrneshing relationship over at least a portion of the rolls, and means adjacent said rolls for holding the blade portion of a tobacco leaf While said rolls draw the stem of said leaf.

12. In a tobacco stemming machine, a pair of adjacent `co-acting rolls disposed on converging axes, at least portions of the rolls having screwthreaded surfaces, and the threads of said portions being at least in part in intermeshing relationship, and means adjacent said rolls for holding the blade portion of a tobacco leaf while said rolls draw the stem of said leaf.

13. In a tobacco stemming machine having a leaf conveyor and a cooperating stem-drawing roll assembly in spaced relation therewith and operated in synchronization thereto, an improved stem-drawing roll assembly comprising a pair of co-acting elongated rolls, said rolls having surface portions provided With screw threads which are at least in part intermeshing, said conveyor being positioned adjacent said rolls and being adapted to hold the blade portion of a tobacco leaf While said rolls draw the stern of said leaf.

14. In a tobacco stemming machine, a pair of adjacent co-acting stem-drawing rolls having bodies of circular transverse section and screw-threads formed on said bodies, said rolls having cooperating stem-receiving ends, said threads being at least in part in intermeshing relationship and being in non-meshing relationship at said stem-receiving ends, and means adjacent said rolls for holding the blade portion of a tobacco leaf while said rolls draw the stem of said leaf.

15. In a tobacco stemming machine, a pair of adjacent co-acting rolls, said rolls having coacting tapering body portions of circular transverse section and cooperating screw threads formed on the surfaces of said tapering body portions, said cooperating threads being in intermeshing relationship along at least a part of said tapering portions', and means adjacent said rolls for holding the blade portion of a tobacco leaf While said rolls draw the stern of said leaf.

LOUIS N. DIBRELL, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 750,161 Briggs Jan. 19, 1904 996,958 Wallick July 4, 1911 1,267,776 Lawrence May 28, 1918 1,347,403 Richter July 20, 1920 1,926,776 Kean Sept. 12, 1933 2,007,236 Zeun July 9, 1935 2,119,162 Hartner May 31, 1938 2,160,703 Markley May 30, 1939 2,303,908 Brashear Dec. 1, 1942 2,359,824 Brashear Oct. 10, 1944 FOREIGN PATENTS Number Country Date 24,930 Germany Nov. 24, 1883

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