US2722039A - Apparatus for obtaining fibers from plant leaves - Google Patents

Description

J. M CRAE Nov. 1, 1955 APPARATUS FOR OBTAINING FIBERS FROM PLANT LEAVES 4 Sheets-Sheet 1 Filed Dec.

uvnulinmunnnfillllimui I INVENTOR ATTORNEY Nov. 1, 1955 J. MCCRAE APPARATUS FOR OBTAINING FIBERS FROM PLANT LEAVES Filed Dec. 14, 1951 4 Sheets-Sheet 2 INVENTOR -4 Ma C1645 ATTORNEY J. M CRAE Nov. 1, 1955 APPARATUS FOR OBTAINING FIBERS FROM PLANT LEAVES 4 Sheets-Sheet 3 Filed Dec. 14, 1951 00.. noon.

INVENTOR J )z/M (5945 ATTORNEY J. M CRAE I Nov. 1, 1955 APPARATUS FOR OBTAINING FIBERS FROM PLANT LEAVES 4 Sheets-Sheet 4 Filed Dec. 14, 1951 IN VENTOR BY MW ATTORNEY United States Patent Office 2,722,039 Patented Nov. 1, 1955 APPARATUS FDR OBTAINING FIBERS FROM PLANT LEAVES James McCrae, Anzures, Mexico Application December 14, 1951, Serial No. 261,647

4 Claims. (Cl. 19-28) This invention relates to a method of and apparatus for deriving fibers from plant leaves.

It is the object of the present invention to provide a process for decorticating the leaves of fiber-bearing plants and directly obtaining the fibers entirely and exclusively in the form of tow, without intermediate manufacturing steps.

The invention is applied particularly to the decortication of the leaves of plants to derive the leaf fibers entirely in the form of tow, in contradistinction to the decortication of the stems or stalks of plants which results in the obtention of bast fibers.

It is another object of the present invention to decorticate vegetable leaves to effect a separation between the fibrous content and the pulpy portions thereof with maximum yield of fibers and with minimum damage thereto as a result of the decorticating and separating operations.

The invention is particularly applicable to effect such separation of fibers from fiber-bearing plant leaves which heretofore has presented many difficulties, the invention being applicable particularly to members of the Liliacae family such as various varieties of Sansevieria; members of the Bromeliacae family such as Annas Sativa, commonly known as pineapple; Aechmea Magdalenae, commonly known as silk grass or Columbian pita; members of the Agave family such as Sisalana, Fourcroya, Gigantea, and others; members of the palm family such as Izote; and members of the banana family such as Musa textilis.

This invention is designed to decorticate plant leaves and to produce the contained fibers directly and in their entirety in the form of tow. This fibrous form is in contradistinction to line fibers in which the fibers are of substantially the same length as the vegetable leaf from which the same is derived and in which the fibers are in substantial parallelism. Different textile manufacturing operations require the fibers employed therein to be in these two different forms, namely, in the tow or line form. For example, in the field of textile technology involving the manufacture of burlap or hessian, the fabric used for bagging and commonly made from jute fibers, it is necessary that the fiber be in the form of tow. Therefore, one of the first steps in jute manufacture is to convert the fiber into a form of tow. In accordance with the present invention the fiber from the plant leaves is produced in the form of tow directly, without the necessity of any converting or additional manufacturing steps.

The method of decortication as commonly practiced with plant leaves involves a scraping and beating action to remove matter extraneous to the contained fibers. This action generally is applied in a direction extending longitudinally to the axis of the leaves and transmits stresses in the same direction to the contained fibers. A well known result of stressing fibers longitudinally by this form of decortication is to break, tear, and otherwise damage a substantial proportion of them. It is also well known that leaves of certain plants which contain fibers of commercial usefulness remain largely unused on account of these longitudinal stresses causing breakage and loss of fibers beyond economical limits.

It is therefore the object of the instant invention to avoid stressing of the fibers longitudinally so that the fibers which are obtained are not broken, torn or otherwise damaged and so that substantially the full and entire fiber content of the plant leaves is recovered without loss or waste or fibers.

The instant invention proceeds upon the principle of exerting a predetermined crushing action on the plant leaves by means of a series of smooth rolls, coupled with a preliminary separation of the fibrous and extraneous components of the plant leaves, which separation is subsequently completed by suitable washing and agitating operations. In order to aprpeciate more fully the functions performed by the crushing rolls and the peripheral movements executed thereby in contact with the plant leaves, it may be helpful to review the physical characteristics of the plant leaves .or vegetable units which are processed in accordance with the present invention.

The plant leaves which are designed to be processed in accord with the invention, and particularly those of the classes mentioned above, consist mainly of fibers and substances extraneous to such fibers, both of which components possess widely differing physical characteristics. Extraneous substances consist mainly of a mass of sacks or cells containing plant elements in a more or less liquid state. The containing sacks are of a delicate membranous-like nature, rupturable by relatively slight pressure. It has been determined that by rupturing all the sacks of extraneous substances, the contained elements may be liberated, and also that those substances adhering to the fibers may be completely detached therefrom in such manner that the fibers are separated in a more or less complete state from all extraneous substances by washing in water.

Fibers contained in the plant leaves are of relatively denser structure than the extraneous substances. A physical characteristic of those fibers is one of relative elasticity. This property may be understood from an examination of the structure of a fiber strand. A strand is a built up structure composed of ultimates or fibrils, held together by the binding or gummy property of ligneous substances. Those ultimates are cotton-like in appearance, are long in relation to their thickness, pointed at both ends, and enclose a cavity, presenting a cellular structure, thickwalled in relation to the enclosed cavity. The cushioning effect thus presented permits pressure to be applied to them of a degree greater than that required to rupture the aforesaid sacks, and upon release of pressure, the cellular ultimates recover their original dimensions. Ligneous substances binding the ultimates together are of a more or less viscid nature, and an appreciable time elapses before pressure causes them to flow.

The combination of elasticity and cumulative cushioning property derived from the many ultimates forming a strand of fiber, and the appreciable time taken for viscous ligneous substances to begin to flow, permits pressure of a momentary nature to temporarily depress or flatten the fiber strands from which they recover their original dimensions upon release of said pressure, at the same time preserving the original tensile strength of the fiber strands by avoiding flow or displacement of the binding ligneous substances.

The sacks of extraneous substances are generally smaller than the thicker and denser fiber strands, therefore those occupying positions between the strands are protected from the pressure required to rupture them. The object of depressing or flattening the strands is to expose those sacks to pressure, thereby causing them to be ruptured and to be detached from adhering to the fibers in so complete a manner that the fibers are separable from the extraneous substances by washing in water.

In order that no longitudinal stresses be imposed upon the fibers of the leaves in order to obtain such fibers in unbroken and undamaged form, specific apparatus is necessary, operating in a critical manner in order to attain these results. Therefore, the invention contemplates the application of pressure to the plant leaves of such a nature as to cause a temporary flattening of the fibers as well as the exposing of the sacks of extraneous substances to the rupturing and detaching action of such pressure, these two results being executed simultaneously. This simultaneous differential action upon the fibers of the plant leaves and upon the extraneous plant matter surrounding them is preferably exercised by rneans of a series of rotary cylindrical rollers, preferably of metal or other rigid surface, presenting a plurality of successive gaps between sets of superposed rollers, which gaps are constant irrespective of the thinness of the material passing between the rollers. The gaps between these rollers are adjusted for the particular material being handled and generally corresponds to a space which is less than the thickness of the sacks of the extraneous substances of the plant leaves being processed and approximately equal to the thinnest part of the thinnest fibers contained in the vegetable leaves. This arrangement permits the flattening of the fibers for the purpose of presenting the sacks of extraneous substances to the rupturing and detaching effects of the pressures exerted by the rolls.

It has been determined that a cooperative relationship exists between the peripheral speed of the hard-surfaced rollers and the material passing through the gaps formed by the successive pairs of rollers. While such speeds may vary from 1,000 to 3,000 feet per minute, the optimum speed in the handling of the leaves of the Sansevieria plant is approximately 2,000 feet per minute. At such speeds the fibers which are depressed or flattened temporarily regain their original dimensions upon the release of pressure and the ligneous elements contained within the fibrous strands remain undisturbed in view of the insufficient time for such elements to begin to flow, whereupon the fiber strands retain their original tensile strength unimpaired. Speeds in excess of the optimum speeds are desirable in order to increase the capacity of the apparatus. However, these speeds are limited by the capability of the operators to feed the successive leaves into the first set of rollers for the pressing operation. Speeds materially lower than the optimum speed have the disadvantage of prolonging the duration of the pressure between the r rollers which results in the displacement of the ligneous elements and their consequent flow, which is responsible for a reduction in the tensile strength of the fiber strands. Another disadvantage of slower speeds is the creation of stresses of a longitudinal nature in the fibers which produce a weakening and possible tearing thereof. This action results from the tendency of the extraneous substances to flow backwards as the vegetable leaves pass between the rollers. These substances, as they accumulate at the entry of the rollers, present a resistance against forward pull of the fibers which have already been grasped between the rollers which gives rise to the undesired stressing of the fibers in a longitudinal direction.

The lowest permissible peripheral speed of 1,000 feet per minute may be employed in the processing of plant leaves of greater succulence than Sansevieria, for example, some of the Agaves.

At the critical optimum speeds, the unpressed part of the vegetable leaves, as they begin to enter between the rollers, present an obstacle to the slower backward flow of the extraneous substances and by arresting this backward flow these extraneous substances are deflected and caused to flow in lateral directions relative to the forward passage of the vegetable leaves. The lateral movement of the extraneous matter prevents a build-up of this matter at the rolls to preclude the possibility of undesirable longitudinal stresses being imposed upon the fibers.

The material discharged from the roller crushing apparatus consists of a mixture of fibers together with extraneous substances which have been more or less completely detached from the fibers, and are in a more or less fragmented condition. Separation of the fibers from those extraneous substances can be effectively carried out by a simple operation of washing in water, and may be carried out as a separate operation.

The final separation of extraneous matter from the fibrous matter is etfected by washing the fibers with water and repeatedly entraining the fibers while permitting the extraneous matter to be washed therefrom. In addition to the washing effects by the current of water, the separation between the two components of the plant leaves is aided by the difference in density between the fibers and extraneous matter, and the separation is ultimately effected by a centrifuging operation which accelerates the separating effects.

Other objects and purposes will appear from the detailed description of the invention following hereinafter, taken in conjunction with the accompanying drawings, wherein Fig. 1 is a front elevation of a preferred embodiment of our invention;

Fig. 2 is a plan view thereof;

Fig. 3 is a vertical sectional view along line 3-3 of Fig. 1;

Fig. 4 is an enlarged longitudinal section of the initial part of the washing and separating apparatus;

Fig. 5 is a longitudinal sectional view of the final part of the washing and separating apparatus; and

Fig. 6 is a sectional view of the frame at the roll spacing adjusting means thereof, taken along line 6-6 of Fig. 2.

In the drawings the main frame of the machine F is shown anchored to a foundation B of any suitable design. A pair of longitudinally extending horizontal frame members 10 and 10 are laterally displaced on the foundation B. Vertical pillars 11 and 12 are mounted at the forward end and at an intermediate point of frame member 10 and vertical pillars 11, 12' are mounted at corresponding points of frame member 10. The vertical pillars 11 and 12 are superposed by a horizontal frame member 13, and another frame member 13' of the same length as member 13, extends between posts 11', 12' and beyond the latter in order to provide mounting space for the driving elements of the washing and cleaning unit of the apparatus. The parts of the frame assembly described above are maintained in integrated relation by means of bolts and nuts. The connections between the lower frame members 10, 10 and the vertical posts are designated by numerals 26, while the connections between the upper frame members 13, 13' and the vertical posts are designated by numerals 27. Spacers 25, of natural or silicone rubber or of resinous or solid fibrous material, are disposed between the upper frame members 13 and 13' and the posts 11, 11 and 12, 12' in order to provide a variable but unyielding displacement between the hard-surfaced cylindrical crushing rolls 17a, 17b and 17c mounted upon and extending between the upper frame members 13, 13' and corresponding rolls of the same size, 18a, 18b and 180, mounted upon and extending between the lower frame members 10, 10'. Journal bearings 15 are mounted on the underside of the frame members 13 and 13 and corresponding journal bearings 16 are mounted upon the upper side of the frame members 10, 10, in order to mount the axles 21 of the upper rolls and the axles 20 of the lower rolls in the respective upper and lower sets of frame members so that the gaps formed between the rolls bear a fixed predetermined relation with respect to the plant leaves adapted to be passed therebetween. The gap corresponds to the thinnest part of the fibers of the leaves and is smaller than the thickness of the extraneous matter surrounding the fibers, so

that as the material is passed between the rollers the thicker parts of the fibers will be compressed temporarily while theextraneous matter will be pressed and broken and flow laterally of the fibers to eifect a detachment of the extraneous matter from the fibrous material.

At the front end of the machine a pair of frame members 14, 14' are mounted on the front end of the vertical posts 11, 11', respectively. Journal bearings 31 and 31 are mounted on the front end of the underside of these frame members and are adapted to receive the journals of a roller 33 operating as a companion to roller 32, which is mounted in journal bearings 30, 30, fixedly attached to the rear edges of the vertical posts 11, 11', respectively.

An endless band 34 is entrained over rollers 33, 32 so that operators standing on opposite sides of the endless band 34 may present the leaves of the plants to be decorticated to the action of the first set of crushing rolls 17a and 18a .with the points of the plant leaves foremost with the plants in a series of overlapping layers disposed in parallel.

The crushing rolls are driven from any suitable prime mover such as an electric motor, internal combustion engine or the like, by a transmission belt 40 driving a pulley 41 which may be coupled to the drive shaft 20a of the first roll 18a either directly or through the intermediary of a clutch. The drive to the other rolls, operating at the same speeds, may be transmitted in any suitable way. As shown in Fig. 3, the drive to the superposed upper roll 17a is transmitted by the intermeshing gears of the same size 42 and 43 mounted upon the respective roll shafts 20a and 21a. The drives to the next successive upper rolls 17b and 17c are transmitted through the intermediary of sprockets mounted on the front end of the shafts 21a and 21b and sprocket chain 44 extending between the aligned sprockets of the latter, and sprocket chain 45 extending between aligned sprockets on the shafts 21b and 210. Likewise the transmission from the first lower roll 18a is transmitted to the other rolls by means of sprocket chain 46 extending between aligned sprockets on the forward end of shafts 20a and 20b and sprocket chain 47 extending between aligned sprockets on the forward end of the shafts 20b and 200. A second sprocket 50 is mounted on the extreme end of shaft 20a, in alignment with a sprocket 51 mounted on the shaft of roller 32 in order to transmit the drive to roller 32 and the conveyor belt 34 entrained thereby by means of chain 48.

A second sprocket is also mounted near the right end of shaft 20c in alignment with a sprocket 54 on a shaft 55 mounted on the far end of lower frame members and 10' for the purpose of transmitting the drive through sprocket chain 56 to the movable parts of the washing and final separating units of the installation. This installation consists of a flighted conveyor 60 trained over lower and upper rollers 57, 58, and inclined to the vertical. This conveyor operates at the outlet end of the roll crushing apparatus wherefrom emanate the fiber in wisp form together with fragmented tissue or extraneous matter and juices in spray form. The conveyor travels at a higher speed than the peripheral speed of the crushing rolls and serves to carry up on the conveyor flights 61 successive batches of the components of the leaves in a separated condition for introduction into the washing and cleaning units of the installation, as shown in Figs. 1, 2, 4 and 5, which are mounted on frame supports F and F".

The fibers with some of the extraneous matter attached thereto are carried into the field of operation of Water sprays 62, 62 acting in diverse directions under a spray shield 69 forming part of the washer housing. These sprays are fed by conduits 63, 63 at the upper ends of the unit which are responsible for the initial washing away of the extraneous matter from the fibers and the removal thereof from the washer casing.

The washer frame consists essentially of an inclined reticulated sluice provided with openings 71 of sufficient size to carry away the flowing water with the particles of extraneous matter intermixed therewith. 'The openings 71 are so small that they do not cause any loss of the fibers which are travelling along the sluice. A sump 72 forms the base of the washing unit for carrying off the wash water and particles of extraneous matter to a suitable point of disposition through the outlet 73, which may be provided with a regulating valve. The effluent not only carries away the plant juices including chlorophyll but also the tissues which are in highly frag:

mented state and of a much higher density than the fibers. The greater density of the extraneous matter gives rise to a stratification between this matter and the fibers so that the tendency for the removal of the latter is enhanced as the material travels along the washing channel along the openings 71.

In order to supplement the cleaning action afforded by the water sprays, the fibers are repeatedly arrested in their travel down the sluice by means of sets of pin members 75 and 75 mounted in cross-bars 95 and 96, respectively, extending across the width of the machine, along spaced parts therealong. Five sets of cross-bars 95, 96 are shown, but a greater or lesser number may be used, depending upon the length of the washing channel and the degree of cleaning sought. Each set of crossbars 95, 96 is mounted at the opposite ends of rocker arms 76, which arms are pivotally mounted on posts 77 disposed along opposite sides of the roof of the washing channel. Oscillating movements are imparted to the rocker arms 76 by means of rollers 78 which are mounted on a common bar 79 on each side of the machine, and which execute a limited to-and-fro movement by virtue of a yoke or terminal strap 80 connected thereto and actuated by an eccentric 81 formed adjacent to each end of shaft 81, mounted on the end of the frame member F. The pins 75, 75 operate within openings in the cover 69 of the washing apparatus and are displaced successively along the width of the washing apparatus in the successive rocking unit assemblies.

The rollers 78 alternately act upon the high points of the rocking bars 76 to alternately depress sets of pins 75 and 75' to give them a rapid up and down movement, separated by a pause in time caused by the dwell in the rocker arms 76. The pins 75', which are shown as extended within the sluice, cause an entrapment of the fibers in their downward travel while the water flow serves to wash away the extraneous particles therefrom. The raising of the pins 75, occasioned by a rocking of the bar 76, results in a release of the fibers for travel down the floor 70 of the sluice until they are again entrapped by a lower row of pins 75 which are now rapidly lowered into the field of flow of the water with the fibers suspended therein. This intermittent entrapment and release of the fibers results in their effective entanglement in tow form while releasing most of the extraneous matter therefrom. The rapidity of the movement of the pins 75, 75' causes them to come into position in the channel before the fibers which have been released from a higher group of pins pass the points where they may be engaged by the succeeding set of pins. The pause in the movement of the pins provides for the retention of the fibers while they are subjected to the washing action of the water current in the channel.

The separating action is carried out in its final stages by the presentation of the fibers and water with whatever portion of the extraneous matter is retained thereby to the field of operation of a rotary drum 85 provided with vanes 86 projecting from the periphery thereof, which drum rotates in a counterclockwise direction within a shell 86' which is perforated at the left side thereof with openings 87. These openings may be /s" in diameter with a scattered pitch of about The water and extraneous particles are thrown out centrifugally through the openings 87 for reception by a suitable sump while the fibers are entrained by means of the vanes 86 and are delivered to the channel 88 in wisp form for delivery to a suitable conveyor or repository for final drying. The resultant product is the fibrous content of the plant leaves in tow form and having but insignificant amounts of extraneous matter adhering thereto which fly or break away from the fibers in the course of the subsequent spinning and yarn manipulating operations.

A regulating valve 89 may be provided at the outlet end of the washing channel to regulate the flow of the water therethrough. This bafiie element may be used to control the degree of flotation of the fibrous material above the layer of the particles of extraneous matter as the same flow down the channel while being subjected to the arresting movements of the pins 75, 75'.

The drive for the movable units of the cleaning apparatus may be taken from the drive of the roll crushing unit. Thus the conveyor 60 may be driven from transmission shaft 55 at the rear lower end of the frame by means of sprocket chain 64 extending between a sprocket on this shaft and another smaller sprocket mounted on shaft 65. A second sprocket is mounted on shaft 55 for transmitting rotary movement to shaft 81 by means of sprocket chain 66. Shaft 81 carries the eccentrics 81 for imparting reciprocating movements to the rocking rollers 78 for actuating the fiber entraining pins 75, 75.

The rotary drum 85 is driven by means of a reverse belt 98 trained over a pair of pulleys mounted on the ends of shaft 55 and the rotary shaft 99 supporting the rotary drum 85.

Variations in the drive for the several moving elements of the apparatus may be made in dependence upon the needs of individual installations.

It is contemplated that guard housings be used wherever such may be necessary, as well as additional SUIIIPS for conducting away the liquid components of the material operated upon by the machine. For example, a sump may be provided on the outside of reticulated screen 86 which may, if desired, be combined with sump 72. Likewise a screen or sump may be provided at the bottom of the conveyor 60 for the purpose of carrying away the plant juices which issue from the last of the crushing rollers and which are not entrained by the solid matter carried on the conveyor 60 to the washing unit.

The amount of wash water employed in the washing of the fibers may be controlled by the introduction of water through the water inlet pipes 63" at each side of the head 7 of the washing channel (Fig. 4)' to supplement the quantity of spraying water fed through conduits 63, 63'.

The installation as described represents a preferred embodiment of the invention for obtaining the fibers from plant leaves, for example, the leaves of the Sansevieria ;f,

plant, the processing of which has heretofore proven uneconomical.

While I have described my invention as embodied in a specific form and as operating in a specific manner for purpose of illustration, it should be understood that I do not limit my invention thereto, since various modifications will suggest themselves to those skilled in the art without departing from the spirit of my invention, the scope of which is set forth in the annexed claims.

I claim:

1. An apparatus for decorticating of plants leaves to obtain the fibers therefrom directly and exclusively in a condition of tow, which comprises a machine frame having lower and upper frame parts supporting rotary members for crushing the plant leaves only, said rotary members comprising a plurality of hard-surfaced cylindrical rolls mounted at displaced points along the lower part of said frame, a plurality of companion hard-surfaced rolls identical to said first-mentioned rolls mounted on the upper part of said frame in overlying relation to said lastmentioned rolls, spacers between the upper and the lower parts of said frame to fix the extent of the gap between said rolls to correspond to the thinnest dimension of the fibers in the plant leaves and less than the thickness of the extraneous substances surrounding said fibers, and means for rotating all of said rolls at a'substantially uniform peripheral velocity which crushes the plant leaves with no transverse strains or breakages and which induces no harmful obstruction to the travel of the fibers through the gaps of said rolls to cause their tensile stressing with a consequent tearing and damage thereof.

2. An apparatus as set forth in claim 1 wherein said rolls have a diameter of approximately eighteen inches and a peripheral velocity of 1,000 to 3,000 feet per minute.

3. An apparatus as set forth in claim 1 wherein said spacers are formed of thin sheets of rubber to impart a slight degree of springiness to the roll mountings.

4. An apparatus as set forth in claim 1 wherein is provided three sets of heavy rolls to effect a crushing of the plant cells containing the extraneous substances.

References Cited in the file of this patent UNITED STATES PATENTS 738,668 Ellis Sept. 3, 1903 1,021,269 Schlichten Mar. 26, 1912 1,089,261 Pos Mar. 3, 1914 1,601,977 McHenry Oct. 5, 1926 1,983,454 Haynes Dec. 4-, 1934 2,238,225 Lang Apr. 15, 1941 2,355,999 Patterson Aug. 15, 1944 2,408,749 Berg Oct. 8, 1946 2,567,938 Hoffman Sept. 18, 1951 2,571,108 Burkardt Oct. 16, 1951

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