US3791286A

US3791286A - Method for compacting fibrous material

Info

Publication number: US3791286A
Application number: US00229532A
Authority: US
Inventors: J Molitorisz
Original assignee: ROTOPAK SYST Inc
Current assignee: ROTOPAK SYST Inc
Priority date: 1972-02-25
Filing date: 1972-02-25
Publication date: 1974-02-12
Anticipated expiration: 1991-02-12
Also published as: FR2173514A5

Abstract

A compressed core of fibrous material is rolled in a single channel defined by a plurality of circumferentially spaced skewed rollers which impart to the core radial, tangential and axial forces. The uncompacted fibrous material fed to the channel is limited to a width less than the length of the channel. The remainder of the channel is a finishing zone. Discharge of the compressed core from the finishing zone is controlled by a density controlling valve. The discharged core is cut into wafers.

Description

United States Patent [191 Molitorisz 1*Feb. 12, 1974 METHOD FOR COMPACTING FIBROUS MATERIAL [75] Inventor: Joseph Molitorisz, Bellevue, Wash.

[73] Assignee: Rotopak Systems, Inc., Seattle,

Wash.

21 Appl. No.: 229,532

Related US. Application Data [63] Continuation-impart of Ser. No. 121,704, March 8,

[52] user. .Q ..100/40 51 Int. Cl 1330b 3/04 [58] Field of Search... 100/40, 86, 89, DIG. 7; 56/1 11/1968 Bushmeyer 100/89 7/1970 Molitorisz 100/89 FOREIGN PATENTS OR APPLICATIONS- 1,024,726 4/1966 Great Britain l00/D1G. 7 1,202,114 8/1970 Great Britain 100/89 Primary Examiner-Peter Feldman ABSTRACT A compressed core of fibrous material is rolled in a single channel defined by a plurality of circumferentially spaced skewed rollers which impart to the core radial, tangential and axial forces. The uncompacted fibrous material fed to the channel is limited to a width less than the length of the channel. The remainder of the channel is a finishing zone. Discharge of the compressed core from the finishing zone is controlled by a density controlling valve. The discharged core is [5 6] References Cited cut into wafers.

UNITED STATES PATENTS 3,386,373 6/1968 Bushmeyer et al. 100/89 6 Claims, 27 Drawing Figures 63- 62 l {q Q Q! 64 l i 11 Q PAIENIED E I 2 3.791.286

SHEET 3 [IF 6 IFIIG.5

FINALLY COM- L I A PRESSED LAYERS Q O figif IFIIG. 113

NEW LAYER COMPRESSED LAYERS FIIIGofi c g W J J CUTTING ZONE 22b I T HNIQHING ,I M IFIIGOIIQ N OI-' vALvE I CHANNEL DIAMETER \L/I/ FIIGJ M. IFIIGOS DIAMETER GENERATED BY ROTATIN'O ROLLER I FIG 9 I AXIAL VELOCITY COMPONENT I OF THE ROLLER AT THE OORE' I IFIIGO M) RAOIAL FORGE ACTING ON WAFER CORE I IFIIGO IIII AXIAL FORCE I i IFIIGO I2 I ANGULAR I I VELOCITY OF THE CORE PATENTEB FEB I 2 I974 SHEU 5 BF 6 PATENTED FEB 1 2 I974 SNEETGGFG FIG, 25

METHOD FOR COMPACTING FIBROUS MATERIAL This application is a continuation-in-part of US. ap-

plication Ser. No. 121,704, filed Mar. 8, 1971.

BACKGROUND OF THE INVENTION l. Field of the Invention This invention pertains to methods for compressing fibrous materials. The invention has particular application to agricultural uses such as the compaction of hay or the like into self-contained wafers, but also industrial utility for the compaction of other fibrous materials. The compaction technique is of the type in which sheets of fibrous material are continuously rolled into a compact core by the imposition of radial, axial and tangential forces in a core forming channel defined by circumferentially spaced rollers. This technique is known in the art as rolling-compressing.

2. Description of the Prior Art The rolling-compressing technique of forming loose fibrous material into a dense cylindrical core and particularly a core suitable for cutting into wafers, had its beginning in the late l950s. Extensive experimental and development work on both the rolling-compressing method and in commercially acceptable apparatus has continued ever since. Early machines are disclosed in the patents to McColly et al., No. 3,316,694, and Bushmeyer et al., No. 3,244,088, for example.

More specifically, rolling-compressing apparatus of cylindrical, conical or hyperboloid channel configurations have been experimented with using skewed rollers, channels with large conical angles, or mechanical means in the channel to provide axial displacement of.

the compressed core. Means have also been provided to produce an axial resistance force in order to achieve a desired core density. However, such apparatus and the rolled wafers produced by such prior art techniques have not satisfied the basic requirements necessary for commercial utilization.

Development work subsequent to the original experimental machines was directed to using two separate, axially aligned channels, as the accepted feasible approach. The receiving or wrapping channels were either conical or quasi-cylindrical with or without skewed rollers. Conical channels, in general, were limited in length by the maximum core diameter and by the cone angle; therefore, the intake capacity of such channels was also limited. Another undesirable feature was that in conical channels the minimum energy input 7 was at the peripheral layers of the core leaving the cut wafers lacking in structural stability. Conical channels produced a core with a maximum density reached at the center of the wafer,creating problems in drying and animal acceptance.

In a conical channel any change in the length of the feed zone or in the position of the intake through the feed zone would cause a change in the core diameter,- thus affecting the core structure'and density and since the intake into the channel was dependent upon roller diameter at the point of intake, the rate varied substantially along the channel. Thus, a feed rate determined by the smaller ends of the rollers would not be the optimum rate acceptable by the larger ends of the rollers. Fluctuations in the rate of intake caused clogging of the channel or interruptions in the continuity of the rolling process.

Rolling-compressing systems with receiving channels v defined by skewed hyperbolic rollers followed by finishing channels defined by skewed hyperbolic rollers were attempted. Such systems were complicated and did not provide adequate and flexible means to control core density nor the necessary flexibility to accept unavoidable intake fluctuations.

Rolling-compressing systems consisting of separate receiving and finishing channels have inherent difficulties in passing thecompressed core from the receiving to the finishing channel. One such difficulty is the accumulation of fibers at the interspace between the two roller systems.

Attempts to improve torque transfer and to prevent adherence of particles on the rollers were made with elastic coatings. Although these functions were achieved to various degrees, the surfacing material did not have adequate wear because of the abrasive nature of the core.

Summarizing, the requirement for a commercially acceptable rolling-compressing machine can, in general, be listed as follows:

a. adequate through-put capacity for both mobile and stationary agricultural applications; a

b. suitable flexibility to accept intake rate fluctuations without significantly affecting quality or density of the core and without endangering the continuity of the rolling process;

c. capability of handling fibrous material with a varying consistency and a wide range of moisture content;

d. a dependable control system to maintain the structural and density consistency of the core;

e. a channel configuration suitable for producing a core with the density and structural stability greatest at the periphery with a loose, easily dried center;

f. a dependable, practical cutting mechanism having adequate cutting capacity without causing undue damage to the core.

SUMMARY OF THE OBJECTS AND FUNCTIONS It is a primary object of this invention to provide a method capable of achieving the previously stated requiremen'ts for a commercially acceptable machine.

It is' an object of this invention to provide a commercially feasible method and apparatus for forming a fribrous material core using the rolling-compressing technique. I I

Another object is to provide a method which embodies the rolling-compressing technique by providing for both compaction and finishing in a single channel.

' Further objects are to provide a method for varying the density of the core, and for obtaining an optimum core density profile and a paraxialalignment of the fibers in the center of the core.

Other objects are to provide a single channel of skewed rollersfor simultaneously imparting radial, tangential, and axial forces to the material core, to increase torque transfer, reduce the elasticity of the fibers and to maintain a nearly constant peripheral velocity ratio throughout the channel length between the rollers and the core.

These objects are obtained by a method basically having the steps of feeding fibrous material into a feed zone less than the length of the channel, tightening the sheet into a cylindrical core by adding additional material and simultaneously imparting radial, tangential, and axial forces to the core, continuing the application of the radial, tangential and axial forces in the remainder of the channel without adding material, and applyin g an external axial resistance force on the core to preclude discharge until the desired density is attained.

In cutting the core into wafers the method furtherincludes the steps of applying a supplementary torque on the core adjacent the channel discharge, sensing a predetermined length of core, and cutting the core when at the predetermined length and in so doing causing a countertorque that is offset by said supplementary torque In the preferred method the cutting is done without applying a supplementary torque on the core adjacent the channel discharge and cutting is continuous.

A form of apparatus employs a single channel defined by a plurality of circumferentially spaced skewed rollers having a transverse inlet and an axial discharge, the channel having a feed zone less than the length of the channel and the remainder of the channel being a finishing zone. The finishing zone must be of a length at least equal to the distance necessary to cause enough revolutions of the core to eliminate deformation of the core, i.e., bring the internal radial stresses in the core into equilibrium with the radial external forces applied by the rollers. Valve means are employed to impart an axial resistance force to maintain the core at the desired density and also provide a supplementary toque. Cutting means are provided adjacent the valve means and slice the core while imposing a countertorque thereon which is offset by said supplementary torque. The length of the wafer is determined by metering means which actuate the cutting means.

In the preferred apparatus the valve is a free-floating passive element which applies only an axial resistance force and not a supplementary torque. Furhermore the metering means may be eliminated since the length of the wafer is adequately determined by the frequency of slices by the cutting means.

The apparatus described is also best considered as based on'the combination of the practical means to produce rolled, compressed, cut core lengths or wafers of a desired structural stability, density profile, and fiber alignment and to produce the wafers at a desired rate. It provides a balanced rate of intake and discharge. It accepts and processes material at a broad range of moisture content. Profile and surface configurations of the compressing rollers transmit the necessary forces and velocities to provide maximum utilization of the available energy. A spring-loaded roller suspension provides means to maintain density consistency of the core and constant energy input during ma terial intake fluctuations. The density control valve has an independent torque input which assists the rotation of the core even at extreme fluctuation of the feeding rate. The rolling-compressing process is accomplished in one channel so that no undesirable accumulation of fibers or other particles can take place.

In the preferred form the density control valve comprises expandable overlapping shoes biased inwardly to provide the axial resistance force on the core. The valve is free-floating to remain centered on the core as the axial center of the core shifts due to the opening of one or more rollers of the core-forming channel.

A unique application of circumferentially-spaced longitudinal roller cleats or ribs provides better torque transfer at any moisture content of the processed material, prevents undesirable adherence of a continuous liquid film on the roller surfaces, and keeps the rollers free from adhering fibers by producing a limited deformation of the core under the action of the cleats or ribs and by allowing the core to expand into the spaces between adjacent cleats or ribs. This produces a limited and desirable slippage between the core and the rollers to keep the roller surfaces clean.

The nearly constant diameter of a single channel combining the receiving and finishing phases in one system is a significant improvement over all previously known rolling-compressing techniques. Because of the nearly constant channel diameter, the length and position of the feed zone may vary within broad limits without unduly affecting the structure or density of the core. The nearly constant diameter receiving section of the channel provides a uniform linear velocity for the incoming layers and thus can improve the wafer structure by maintaining the even distribution of the thickness of the incoming layer along the feed zone.

The present invention provides an orientation of the incoming fibers or sheets of fibers which arranges these fibers to give an optimum structural form to 'the core. This optimum form exists when the fibers around the center of the core are arranged nearly parallel to the axis of rotation with the relative angle of these fibers increasing toward the periphery of the core. The nearly parallel arranged fibers at the center of the core provide improved drying and provide minimum structural stability for the core at the critical section where the animal would have the most difficulty destroying the wafer. At the same time the outer layers of the core are tightly wrapped providing overall structural stability.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall perspective of a rollingcompressing machine embodying the principles of the invention.

FIG. 2 is a schematic isometric illustrating the drive train for the machine shown in FIG. 1.

FIG. 3 is a section of the valve mechanism employed in the machine of FIG. 1.

FIG. 4 is an isometric of the valve mechanism shown in FIG. 3.

FIG. 5 is a schematic illustrating the relative position of th layers in the core during the core forming process.

FIG. 6 is a diagrammatic illustration of the exterior of the core with the taper exaggerated.

FIG. 7 is a plot of channel diameter versus channel length.

FIG. 8 is a plot of roller diameter as generated by the rotating roller versus channel length.

FIG. 9 is a plot of the axial velocity component of the roller at the core versus channel length.

FIG. 10 is a plot of radial force acting on the wafer core versus channel length.

FIG. 11 is a plot of axial force acting on the core versus channel length.

FIG. 12 is a plot of the angular velocity of the core versus channel length.

FIG. 13 is a diagram of the forces acting on the core.

FIG. 14 is a schematic illustration of a core-forming channel with the taper exaggerated.

FIG. 15 is a diametrical cross section of cut core length such as a wafer W.

FIG. 16 is a plot of core density versus diameter of the core.

FIG. 17 is a section of a typical roller cleat configuration.

FIG. 18 is an end elevation of the cleats as shown in FIG. 17.

FIG. 19 is a schematic cross-sectional view through the discharge end of the finishing zone and looking toward the discharge end.

FIG. 20 is an isometric of a preferred form of density valve used on the basic machine illustrated in FIGS. 1 and 2 as a substitute for the denisty valve 42.

FIG. 21 is a diameterical section of the valve of FIG.

FIG. 22 is an operational schematic illustrating the preferred valve in a closed non-actuated position.

FIG. 23 is an operational schematic illustrating the preferred valve in a normal actuated position.

FIG. 24 is an operational schematic illustrating the preferred valve in a more extended actuated position.

FIG. 25 illustrates a spindle and guard plate used on the preferred form of the machine shown in FIGS. 1 and 2.

FIG. 26 is a schematic end elevation viewed from the discharge end of the machine illustrating the preferred spindle and guard plate.

FIG. 27 is a schematic side elevation of a modified roller biasing means.

DESCRIPTION OF THE PREFERRED EMBODIMENT For the purpose of this description the invention is illustrated as applied to agricultural apparatus especially designed for movement through a field of a fibrous material crop such as hay. The details of this apparatus are described in my copending application, Ser. No. 121,700, filed Mar. 8, 1971 now Pat. No. 3,691,941, and only sufficient description to understand the principles of this invention will be further described. It should be understood that the principles of the present invention have wider application than agricultural apparatus and are suitably applicable to the compaction of any fibrous material such as, for example, crops, refuse, wood, and paper. The principles are equally applicable to stationary apparatus as well as mobile.

The mobile agricultural apparatus illustrated includes a drawbar secured to a trailer frame 12. Feed conveyors 14 powered from a shaft 106 deliver the fibrous material such as windrowed hay H rearwardly into the core-forming portion of the apparatus. In the particular embodiment illustrated the means for compacting thefibrous material into a cylindrical core C includes two transversely spaced, axially aligned sets of

rollers

16 and 18. The rollers are powered by a suitable drive train which is connected through a suitable gearbox 21 to the conventional power take-off of a tractor. Each of the sets of rollers is identical and the 'rollers in each set are circumferentially spaced to define a respective single channel for forming the sheets of fibrous material into a compacted cylindrical core. The double sets of rollers uniquely provide for simultaneous compaction of two cores; however, for the purpose of this description only one set of rollers and its operation will be described.

Each roller set 16 and 18 includes four rollers 16a-d and 18a-d, respectively. These rollers are circumferentially spaced and define in general a core-forming channel 22, the shape of which is approximated for the purposes of this description as first and second

frustoconical sections

22a and 22b joined at their smaller diameter ends. The shape of the channel is caused by skewing the discharge ends of the rollers approximately 3' relative to the channel axis. A space is provided between

rollers

18a and 180 to provide a transverse inlet 24 into the channel. As will be described in more detail the skewing of the rollers provides the core formed within the channel with an axial velocity component to move the core toward the channel discharge 25.

The rollers are powered by the drive train 20 through a plurality of gears 28a-d to thus drive the rollers in a common direction. The rollers are suspended in a manner suitable to transfer torque to the core, and to withstand radial and axial forces between the core and rollers. A preferred and unique suspension is detailed in said copending application, Ser. No. 121,700. The discharge ends of the forward pairs of

rollers

16a, 16c and 18a, and 180 are mounted for radial movement relative to the channel and are spring-biased inwardly by a re spective biasing mechanism 32. For the purpose of this description the biasing details are only shown for roller set 16 in FIG. 1, since the details of the two roller sets are identical. The biasing mechanism includes a pair of spaced arms 120a pivotally mounted to the frame 43 at 121 and providing journals for the rollers 16a,.16c forward of the pivots. The forward ends of the arms are biased toward one another by a tension spring 124 which is coupled at its lower end to the lower arm 120a and is connected at its upper end to an adjustable hook 122. This hook slidably extends through the upper arm and threadably receives a nut having a handle 123 for adjusting the tension of the spring. A pair of stops 125 on the end plate 43 limit the inward swing of the arms 120-120a to thereby define the minimum feed opening between the rollers 16a, and 160. The other ends of these rollers are driven through a ball-type coupling 134 shown in FIG. 17, permitting the rollers to pivot while skewed so that their spring-loaded ends can move in and out to accommodate fluctuations in the quantity of material entering the feed opening. The

other rollers

16b and 16d are not spring-mounted at either end.

In a preferred form of the apparatus the discharge ends of the

rollers 16a

16d and 18a 18d are mounted for radial movement relative to the channel and are spring-biased inwardly by a modified biasing mechanism best shown in FIG. 27. The biasing mechanism for each set of rollers includes a pair of spaced arms 120 pivotally mounted to the frame and providing journals for all four rollers forward of the pivots 121. The forward ends of the arms are biased toward one another by a tension spring 124a and are interconnected by hinged linkages 200. The hinge is provided with a roller 202 that rides in a track 204 fixed to the frame.

Stops

206 and 208 limit movement of the roller 202. An over-center latch 210 is provided to hold the spring and may be swung clockwise as viewed in FIG. 27 to release the bias on the rollers for opening the channel when desired. The hinged linkages allow radial movement of the arms, provide a guided support for the arms taking up the forces exerted by the weight of the rollers, the weight of the arms and of the core. Through this hinged support the core remains to be a supported body at any operating condition of the machine, rather than becoming a supporting element under certain operating conditions. The properly designed pivoted support for all

boundary rollers

16 and 18 also reduces the shifting of the rotational axis of the core when the core diameter changes due to the fluctuating rate of intake of the system.

Due to torsional displacement of the discharge ends of the rollers the peripheral velocity vector of any point on each rollers surface will have tangential and axial components relative to the channel axis. Because all forces producing the rotation and axial displacement of the material in the confined channel are transmitted through the surface friction between the rollers and the material in the channel, the maintenance of a substantially constant relative peripheral velocity ratio between the rotating rollers and core throughout the channel is essential. This peripheral velocity ratio is obtained by correcting the profile of the roller. As best shown in FIGS. 17 and 18, the rollers are provided with longitudinal, circumferentially spaced rigid cleats 36 formed with their largest radial thicknesses toward the ends of theroller and tapering down to a smaller radial thickness at the midsection of the roller. Through these cleats 36 the diametrical ratio between the rollers and core is made nearly constant along the entire length of the channel. The channel shape resulting from the skewed and cleated rollers is approximated as quasicylindrical or two frusto-concical sections joined at their converging ends as shown exaggerated in FIG. 14.

The grooves between the cleats may be of constant diameter, since the cleats provide all of the correction to the channel shape. The effective roller diameter is illustrated in FIG. 8. FIG. 12 illustrates the substantially constant angular velocity of the core resulting from the corrected configurations of the channel and rollers.

At this point it is appropriate to define the various products resulting from roller-compressing apparatuses. Roll wafers vary from 1 to 4 inches in diameter, rolls from 4 6 inches and bales from 10 inches and larger. In a preferred form of the apparatus, particularly for making hay rolls 5 inches in diameter, the circumferentially spaced rigid cleats have constant thickness along the entire length of the rollers. The relative change in the core diameter at the midsection of the channel caused by the skewed roller system is small for a large diameter core, therefore, the modification in the rotational symmetrical body defined by the cleats is not necessary.

For a constant roller diameter the axial and tangential velocity components are constant along the entire length of the channel.

The adhesion of hay particles to the surface of the rollers is prevented by suitable spacing between the cleats 36 so that the material is flexed at the maximum radial stress zone. Limited slippage will result between the rollers and core which is sufficient to make the rollers self-cleaning. The spacing also allows the liquids squeezed from high moisture content materials to be removed from the surface of the cleats. Torque transfer is improved by the gear effect between the roller and the compressed core. Furthermore, the bending and crushing of the long fibers and stem of the material desirably reduces the elasticity of the fibers.

The skewing of the rollers provides an axial velocity component to move the core through the channel. This axial velocity component is best illustrated in FIG. 9.

Because of the varying effective roller diameter theaxial velocity is not constant and reaches its maximum value, approximately 1 fps, at the two ends of the channel and its minimum value at the midsection. A similar functional relationship exists for the tangential velocity causing rotation of the core; however, the effective roller diameter will provide a substantially constant tangential velocity ratio between the roller and core throughout the length of the channel.

It is helpful in understanding the invention to understand what happens to the material in the channel. The radial forces acting on the core C from the roller 18 are determined by two factors: the geometrical configuration of the channel and the quantity of material in the channel. The density of the core varies along the length of the channel due to the increase in the number of wrapped layers of fibrous material. The density increases toward the discharge end of the channel If the feeding zone L of the channel would end at the midsection of the channel where the channel has its minimum diameter, the maximum radial stresses would be applied also at the midsection of the channel, allowing the radial expansion of the core toward the diverging discharge of the channel. Such a relationship is highly undesirable because the structural stability of the peripheral layers of the core is affected by the magnitude of the acting radial stresses and by the number of revolutions the core is making in the maximum radial stress zone. There is a nearly constant radial stress zone, between the discharge end of the channel and the respective end of the feed zone L, designated the finishing zone in FIG. 6, which is the result of the gradual wrapping action of the outer layers of the core stretching the peripheral layers on the already formed core.

It is an important feature of this invention that the length of the feed zone L be less than the total length of the channel by a distance at least sufficient to allow the number or revolutions of the core to occur which is required for the core to achieve the necessary structural stability to give integrity to wafers cut from the core. This distance will vary depending on many factors, but for hay, is equal to the axial displacement of the core occurring during about 10 revolutions of the core beyond the feed zone in the illustrated embodiment.

In the finishing zone the internal radial stresses in the core are brought into equilibrium with the radial forces exerted by the rollers. Basic to this is the fact that in a core formed of rolled layer of fibrous material each next outer layer will upon rolling lag circumferentially behind the next inner layer so long as the core continues to bulge outwardly between the rollers as indicated by the broken line portions in FIG. 19. When the transverse cross section of the core becomes substantially circular in the finish zone as shown by the full line periphery of the core in FIG. 19, additional rolling will not retard the outer layers relative to the inner layers and the core will not become more tightly wound.

FIG. 11 illustrates the axial forces acting on the core along the length of the channel. The magnitude of the axial forces is determined by the magnitude of the radial forces and by the skewing angle of the roller and will also depend upon the fractional coefficient. The

effect of the axial forces caused by the conical geometrical configuration of the sections of the channel is minimal in relation to the frictional forces between the rollers and the core and thus can be ignored. The maximum axial forces are found at the finishing zone in the channel where the already formed core has its maximum structural stability and thus can accept the axial forces without damage to the core. These axial forces can be approximated by a pulling action without afiecting the not finally formed portion of the core still in the feed zone L. Immediately following the discharge of the channel an axial resistance force is introduced in a manner later to be described.

FIG. illustrates the layering of the core during movement of the core through the channel. As the illustration indicates, the layers to the left, i.e., the newly introduced sheets of fibrous material, show little compaction. The layers in the finishing zone to the right of the feeding zone L gradually become approximately parallel, indicating that the compressibility of the core has become in equilibrium with the externally applied radial forces.

FIG. 13 illustrates the force components acting on the core. Forces Fr represent the externally radial forces applied by the rollers. Each radial force Fr is broken down into a frictional axial component Fa and a frictional tangential component Ft. Arrow 40 represents the rotational directional of the core caused by the tangential force Ft. At the right hand end of the diagram radial forces Frv are shown applied by the density control valve and these forces have frictional tangential components Ftv and frictional axial components Fav. All other external forces are indicated by the arrow Fae.

ln the preferred form of the invention the density control valve applies only a passive frictional force and therefore the functional tangential component Ftv is eliminated.

As thus far described, it has been shown that a cylindrical compacted core is formed in a single skewed roller channel without an additional means for providing the axial force on the core. It can also be seen that an important aspect of the single channel utilization is a proper correction of the roller diameters and the limitations on the length of the feed zone L to allow for finishing the core.

Another important factor is to produce a core of the desired density, for example 30 50 lbs. per cu. ft. for hay. This requires that the core not be discharged from the channel prior to reaching this density. As illustrated in FIG. 1 a density control valve 42 is positioned on a sideplate 43 of the vehicle frame adjacent the discharge 25 of the channel 22. One purpose of the valve is to provide an axial force resisting the axial force imposed by the rollers in the channel thus preventing discharge of the core until the roller imposed axial forces exceed the valve imposed axial resistance force. As willbe seen the axial resistance is applied in such a manner that no relative rotational movement occurs between the valve and the core thus preventing damage to the outer layer of the core.

Another purpose of the valve in one form of the invention is to provide a torque supplementing the torque produced by the rollers to offset the countertorque applied during cutting of the core into cylindrical wafers by the cutting blades 46 of the cutter 45 which is powered by a drive 48. The supplementary torque also helps overcome rolling resistance in the channel. The valve 42 includes an annular ring 56 which is secured to the side frame 43. The annular ring mounts a pair of bearings 58, the inside races of which are secured to a rotatable ring 60. A belt drive 61 powers the rotatable ring at the same angular velocity as that of the core. A

plurality of circumferentially spaced leaf springs 62 are secured to the rotating ring 60 and are permanently bent to have a wide entrance 63 of a diameter larger than the discharge of the channel so that expansion of the channel by the radial movement of the

rollers

18a and 18c will allow the larger diameter core to still fit within the entrance of the valve. The leaf springs form an exit 64 of a diameter smaller than the normal diameter of the core so that the core will always engage the leaf springs somewhere along their length. Supplementary coil springs 66 are secured around the leaf spring adjacent the exit 64. The coil springs are adjustable in tension to adjust the magnitude of the resistance force. In one form the springs are secured to the rotating ring 60 by the clips 68. When cutting is provided for, a metering means is employed to measure the length of the wafers and a rotatable ring 52 supports the core during cutting. The wafers are removed by an elevator There is an important relationship between the valve 42 and the radial biasing springs 124. It is desirable to 7 allow the channel 22 to expand radially when a fluctuation occurs in the infeed rate, such as when a slug of hay enters the channel. If the radial spring force is too great, the slug will cause too great an increase in core density, producing a wafer out of the desired density range. If the radial spring force is too small, the channel will continually expand, causing undesirable changes in core diameter. It is also apparent that an adjustment to the'springs 66 on the valve will change the magnitude of the axial resistance force on the core. This change must be offset by an increase in the radial forces imposed by the rollers, since the axial driving force of the rollers is the axial component of this roller radial force. Since a change in axial resistance force changes the magnitude of the roller radial forces, it also has an effect on the radial spring force of the springs 125. Thus, the important relationship is the synchronization of radial biasing force with axial resistance force. Although this would be done manually in the apparatus illustrated, it is also obvious that an automatic synchronization could be accomplished by suitable means.

One of the primary uses of lengths, such as wafers or rolls W, cut from a compressed core C of fibrous crop materials is a food for animals. Consequently the cut lengths must be of an optimum density profile throughout their cross section so that the animal will have no difficulty in tearing apart the product or unwrapping it and eating and digesting all of the material. At the same time the wafers must have adequate structural stability. for mechanized handling. Furthermore, it is often necessary to store the wafers and thus it becomes imperative that its center-allow air circulation for effective drying.

The rolls of this invention have a density profile as shown in FIG. 16 which is a plot of density versus the diametrical cross section of a length cut from the core C, As illustrated, the density at the center of the core is very low, whereas the density at the outer peripheral layers of the core is much greater. As a result the animal can unwrap the outer peripheral layers and then continue eating the remainder of the product with great ease; however, the outer layers are also structurally strong enough to withstand normal mechanized handling. This density profile is also illustrated in a diametrical cross section of the core shown in FIG. 15. As illustrated, the outer layers are more dense than the inner center of the core. I

As also illustrated in FIG. 15, the fibers, such as the stems S, in the low density center of the core are paraxially aligned, rather than being wrapped around the core as in the fibers of the outer layers. The important advantage derived from this is that the cut lengths of core thus have natural air circulation paths through the center of the core to give more uniform drying throughout the product.

The manner by which the above density profile and alignment of the stems in the core center are obtained is best understood by referring to FIGS. and 9. In FIG. 5 the triangular areas a-a designate the approximate longitudinal cross-sectional shape of the portion of the feed zone of the channel 22 which is filling with incoming loose fibrous material a start a new layer. Considering one area, all of the material therein at a given transverse cross section experiences the same axial velocity in the disharge direction. The tangential velocity of the individual stems and particles of the material, however, varies from zero at the center of the channel to a maximum at the periphery of the channel, which maximum is equivalent to the tangential component of the peripheral velocity of the rotating rollers. As a result of this varying tangential velocity a fiber, such as a stem, which is introduced at the center of the core makes approximately a 90 bend and is pulled into a paraxial alignment with the axis of the core whereas a stem introduced further out toward the periphery of the channel follows the alignment of the angle of the resultant velocity causing them to be wrapped around the core.

It has also been discovered that the diameter of a core forming channel formed by the skewed roller configuration of this invention must be large enough so that the maximum radial forces acting on the core by the rollers never attain a close proximity with the center of the core. Otherwise, a product will result having an undesirably dense, hard, center core. By the present invention the peripheral core layers get wrapped tight but the center remains loose.

From the foregoing description it is seen that the method of this invention comprises feeding a layer of fibrous material, such as hay I-I, along a feed path, rolling the material in a channel formed by a plurality of circumferentially spaced rollers, forming the layers into a core by the application of radial, tangential, and axial forces on the fibrous material, deforming the layers of the core as it is being rolled to tighten the layers about one another to increase the density of the core, finishing a length of the core by continuing the rolling of the core in the same continuous channel in the absence of additional layers of fibrous material until the cores interanl radial stresses are brought intoequilibrium with the externally applied radial forces, and imposing an axial resisting force on the core to retain the core under the influence of the rolling forces until the axial component of the rolling forces exceeds the axial resistance force so as to assure the desired density is obtained in the core without damaging the external layers thereof.

In the preferred form of the invention the density control valve 220 as shown in FIGS. 21 24 comprises a plurality of four overlapping shoes 221 pivotally mounted by double pivot linkages 222 to a floating ring 224. Each linkage includes a first pivot member 226 pivotally secured to the ring 224 and a second pivot member 228 secured to the shoe and pivotally mounted on the first pivot member 226. As is readily seen in FIGS. 22 24, the shoes are free to assume an outwardly converging position as in FIG. 24 and then can move into parallel positions as shown in FIGS. 23 and 24 with their full inner surfaces in contact with the rotating core C, thus reducing the magnitude of the biasing force required on the shoes to provide the desired frictional resistance on the core. Since there is no cover around the shoes, particles of hay pulled from the core can pass out through the shoes without clogging. In the position shown in FIG. 22 the shoes extend into the core-forming channel to prevent discharge of the core material around the valve.

The preferred valve 220 is a floating passive element applying only an axial resistance force on the core C and can move laterally with the core to remain centered thereon. When the

rollers

18a and 18c open to expand the core-forming channel, the center of the channel shifts slightly. Accordingly, the valve optimumly should shift also and remain centered on the core. Furthermore, a change in core diameter will change the angular velocity ratio of the rollers 16 and core C. Optimumly the valve speed should change to equal the speed of the core. To accomplish these purposes the ring 225 is retained adjacent the end plate 43 by three spaced bearings 230. Each bearing includes a flanged roller 232 which prevents the .ring from moving radially past the bearings. In the preferred form the ring is spaced a slight distance from each flange when the ring is centered between the bearings. Likewise the ring is prevented from moving axially past the bearings by the rollers. When engaged by the core C, the shoes 221 will center and remain centered on the core with the full inner surfaces of the shoes engaging the core. In the fully expanded position as shown in FIG. 24 the shoes will part; however, during most of the operation of the valve the overlap of the shoes will maintain a continuous surface acting on the core.

The shoes 221 are biased inwardly by a conventional elastic cord 236, the tension of which can be readily adjusted by any conventional cord tightening device. Rivets 238 prevent the cord from slipping from the shoes.

In addition to the preferred density control valve 220, the preferred form of apparatus also includes a short powered spindle 240 at the intake end of the core-forming channel, as shown in FIGS. 25 27. The spindle 240 is tapered toward the discharge end of the channel and is keyed to gear 105. The length of the spindle is approximately one-third the length of the channel and one-half the length of the theoretical feed zone of the channel. Thus the spindle acts on the incoming hay only for a short period and is used to assist the rollers 18 in starting a core C in an empty channel. A deflector plate 242 is also added to the preferred apparatus. The deflector plate extends along the length of the feed zone of the channel and guides the incoming hay away from the roller 18:: as shown in FIG. 26.

While the preferred form of the invention has been illustrated and described, it is understood that it is capable of modification and addition without departing from the principle thereof. Accordingly, the invention is not to be limited to the exact form illustrated, but only by the literal interpretation of the claims appended hereto.

What is claimed is:

l. A method of forming a cylindrical core of fibrous material comprising the steps of feeding a layer of fibrous material along a feed path, rolling the material by applying radial, tangential and axial forces on the material in a forming channel defined by a plurality of circumferentially spaced skewed rollers, thus forming the material into a compressed core comprised of plural layers of material, deforming the. layers of the core as it is being rolled to tighten the outer layers about the inner ones to increase the density of the core, finishing the core to bring the compressibility of the core into equilibrium with the externally applied radial forces by continuing the rolling of said core for a plurality of revolutions in the forming channel in the absence of additional fibrous material and imposing an axial resisting force on the core to maintain the radial, tangential and axial forces on the core until the axial frictional force within the channel exceeds the axial resisting force so as to assure the core reaches the desired density.

2. The method of claim 1, including relieving abnormally high radial forces on the material due to a temporary increase in the in-feed rate of fibrous material by radially expanding the channel.

3. The method of claim 1, said step of deforming including intermittently sharply bending and crushing the fibers almost to their yield point to reduce the elasticity of the fibers.

4. The method of claim 2, said step of applying an axial resistance force including applying a supplementary torque on the core in the same direction as, the torque resulting from the roller imposed tangential forces, and cutting the core into cylindrical lengths by slicing the core whereby the counter torque applied by slicing is offset by said supplementary torque.

S. The method of forming a compact, substantially constant density,cylindrical core of fibrous material in a wrapping channel defined by a plurality of circumferentially spaced rollers, said channel having a transverse inlet defined by two radially movable biased rollers and an axial discharge, comprising feeding a sheet of fibrous material through the inlet into a feed zone less than the length of the channel, tightening the sheet of material into a cylindrical core by adding additional material and applying with the rollers radial, tangential and axial forces on the core, continuing the application material, applying an adjustable axial resistance force against the core to preclude the discharge of the core of said radial, tangential and axial forces on the core in I the remainder of the channel without adding additional from the channel until the axial force transmitted by the roller exceeds the axial resistance force to maintain the desired density, adjusting the axial resistance force to vary the core density, and adjusting the'radial inwardly biasing force to a magnitude dependent upon the magnitude of the adjusted axial resistance force to maintain the roller in their positions during normal infeed rates, but allowing the rollers to open during temporary high in-feed rates to maintain the desired density.

6. A method of forming a cylindrical core of fibrous material comprising the steps of:

a. continuously feeding fibrous material along a feed path to a feed zone which merges directly without interruption with a finsihing zone separated from the feed path and defining with the feed zone a straight continuous forming channel having a forming axis extending at cross angles with respect to said feed path,

b. continuously applying radial, tangential and axial forces to the fed material along circumferentially spaced rotary force-applying surfaces spaced radially from said forming axis and extending the length of the forming channel in skewed relation to said forming axis, in such a manner as to continuously roll the fed material into a generally cylindrical axially-moving core which is loosely wrapped in the feed zone and has its wraps progressively tightened in the finishing zone to give the core a predetermined density by the time the core has advanced through the finishing zone to a discharge point, the outer wrap of the core being free to bulge radially outward between said force-applying surfaces until said predetermined density is achieved,

c. and continuously applying to the core at said discharge point an axial resisting force of such a magnitude as to keepthe periphery of the core pressed against said force-applying surfaces throughout the length of the finishing zone and assure that the core reaches the desired density.

Claims

1. A method of forming a cylindrical core of fibrous material comprising the steps of feeding a layer of fibrous material along a feed path, rolling the material by applying radial, tangential and axial forces on the material in a forming channel defined by a plurality of circumferentially spaced skewed rollers, thus forming the material into a compressed core comprised of plural layers of material, deforming the layers of the core as it is being rolled to tighten the outer layers about the inner ones to increase the density of the core, finishing the core to bring the compressibility of the core into equilibrium with the externally applied radial forces by continuing the rolling of said core for a plurality of revolutions in the forming channel in the absence of additional fibrous material and imposing an axial resisting force on the core to maintain the radial, tangential and axial forces on the core until the axial frictional force within the channel exceeds the axial resisting force so as to assure the core reaches the desired density.

4. The method of claim 2, said step of applying an axial resistance force including applying a supplementary torque on the core in the same direction as the torque resulting from the roller imposed tangential forces, and cutting the core into cylindrical lengths by slicing the core whereby the counter torque applied by slicing is offset by said supplementary torque.

5. The method of forming a compact, substantially constant density,cylindrical core of fibrous material in a wrapping channel defined by a plurality of circumferentially spaced rollers, said channel having a transverse inlet defined by two radially movable biased rollers and an axial discharge, comprising feeding a sheet of fibrous material through the inlet into a feed zone less than the length of the channel, tightening the sheet of material into a cylindrical core by adding additional material and applying with the rollers radial, tangential and axial forces on the core, continuing the application of said radial, tangential and axial forces on the core in the remainder of the channel without adding additional material, applying an adjustable axial resistance force against the core to preclude the discharge of the core from the channel until the axial force transmitted by the roller exceeds the axial resistance force to maintain the desired density, adjusting the axial resistance force to vary the core density, and adjusting the radial inwardly biasing force to a magnitude dependent upon the magnitude of the adjusted axial resistance force to maintain the roller in their positions during normal in-feed rates, but allowing the rollers to open during temporary high in-feed rates to maintain the desired density.

6. A method of forming a cylindrical core of fibrous material comprising the steps of: a. continuously feeding fibrous material along a feed path to a feed zone which merges directly without interruption with a finsihing zone separated from the feed path and defining with the feed zone a straight continuous forming channel having a forming axis extending at cross angles with respect to said feed path, b. continuously applying radial, tangential and axial forces to the fed material along circumferentially spaced rotary force-applying surfaces spaced radially from said forming axis and extending the length of the forming channel in skewed relation to said forming axis, in such a manner as to continuously roll the fed material into a generally cylindrical axially-moving core which is loosely wrapped in the feed zone and has its wraps progressively tightened in the finishing zone to give the core a predetermined density by the time the core has advanced through the finishing zone to a discharge point, the outer wrap of the core being free to bulge radially outward between said force-applying surfaces until said predetermined density is achieved, c. and continuously applying to the core at said discharge point an axial resisting force of such a magnitude as to keep the periphery of the core pressed against said force-applying surfaces throughout the length of the finishing zone and assure that the core reaches the desired density.