US3475791A

US3475791A - Method for separating,conveying and collecting woodpulp fibers as a uniform layer and apparatus for carrying out the same

Info

Publication number: US3475791A
Application number: US636742A
Authority: US
Inventors: Charles A Brewster; Charles H Plummer
Original assignee: Johnson and Johnson
Current assignee: Johnson and Johnson
Priority date: 1967-05-08
Filing date: 1967-05-08
Publication date: 1969-11-04
Anticipated expiration: 1986-11-04
Also published as: DE1955237A1; DE1955237C3; AU440763B2; AU6332769A; DE1955237B2; GB1231847A

Description

Nov. 4, 1969 c. A. BREWSTER ET AL 3,475,791

METHOD FOR SEPARATING. CONVEYING AND COLLECTING WOODPULP FIBERS AS A UNIFORM LAYER AND APPARATUS FOR CARRYING OUT THE SAME I Filed May 8, 1967 3 Sheets-Sheet 1 INVENTO RS. (244E155 ,4. PE'h STE/P CAM/PIES mam/v5? ATTO NEY Nov. 4, 1969 c. A. BREWSTER ET AL 3,475,791

METHOD FOR SEPARATING, CONVEYING AND COLLECTING WOODPULP mamas AS A UNIFORM LAYER AND APPARATUS FOR CARRYING OUT THE SAME Filed May S, 1967 3 Sheets-Sheet 2 ATTORNEY.

Nov. 4, 1969 c. A. BREWSTER ET AL 3,475,791

METHOD FOR SEPARATING. CONVEYING AND COLLECTING WOODPULP FIBERS AS A UNIFORM LAYER AND APPARATUS FOR CARRYING OUT THE SAME Filed May 8, 1967 3 Sheets-Sheet 5 INVENTORS: 6/IARAES ,4. 5/PEW57'ER Can/P45; fl P441 MEI? ATTOR EY United States Patent US. Cl. 19-1563 17 Claims ABSTRACT OF THE DISCLOSURE Method and apparatus for individualizing woodpulp fibers, conveying said individualized fibers without agglomeration and collecting said individual fibers as a uniform layer of loose fibrous material. The method comprises feeding the fiber material to be separated to the center of a pair of rotatable discs and applying forces to separate the fibers. Forcing the separated fibers out the edges of the discs, continuously and substantially immediately conveying said individualized fibers at substantially right angles to the edges of the discs and conveying the fibers away from said discs in turbulent form. Collecting the fibers on a surface while removing the air from said fibers without disrupting the flow of fibers or their formation on the collecting means.

This invention relates to methods and an apparatus for separating woodpulp board into individual fibers, maintaining the fibers in their individualized condition and collecting these fibers in a uniform layer of loose fibrous material. More particularly this invention relates to separating pulpboard into individualized fibers utilizing disc refiners or attrition mills and collecting the fibers on a screen or a similar foraminous material while dissipating the air so as not to disrupt the fibers and obtain a uniform distribution of the individualized fibers.

Two of the main advantages of woodpulp fibers are their very high absorbent characteristics and their low cost. Some of the main disadvantages of such fibers are that they are short, quite difficult to work with and process, readily tend to mat or cling to themselves forming hard knobs or balls and if wet processed form thin, paper-like rather than fabric-like sheets.

Because of their high absorbency, woodpulp fibers have long been formed as loose fibrous masses or batts to be used as absorbent medias, however, in most all instances these batts are covered by paper wadding, lightweight fabrics or similar materials to stabilize the woodpulp and prevent it from linting or dusting. The cover on the batt allows the batt not to be as uniform as if the cover were not present and hence some balling or felting of the fibers can be tolerated. Also, because of their low cost, woodpulp fibers would appear to have great advantage as the basic component of a fabric, however, most of the woodpulp fiber today is processed in water or other liquids which produces a paper product which lacks drapeability, softness and the required hand for many end uses. It has been believed that if woodpulp fibers could be proc essed in the absence of excess Water so that they would maintain softness, bulk, drapeability and other desirable properties, there would be many more end uses for the woodpulp fibers.

The original woodpulp board of compressed woodpulp fibers has a moisture content by weight of from about 3 to 6 percent. In processing such woodpulp fibers in accordance with the present invention a maximum of about 10 percent by weight additional moisture is added to the woodpulp fibers. The total moisture content of the 3,475,791 Patented Nov. 4, 1969 "ice fibers during the entire processing is maintained at less than about 16 percent and usually more than 3 percent. The preferred moisture content of the fibers is from about 12 to 15 percent by weight. The low moisture contents cause static problems, increase fire hazard, increase fiber breakage, etc. The high moisture contents, above about 20 to 30 percent, make the fibers hard to separate, and once separated increase the possibility of fiber agglomeration and the formation of balls of fibers.

We have now discovered method and apparatus for processing woodpulp fibers in air so that they may be collected in loose fibrous form. Our new method and apparatus substantially eliminates breakage of fibers and very efficiently separates fibers and allows them to be collected in a uniform, loose' fibrous layer with very few, if any, clumps or neps. Hence, my fibrous material may be bonded to maintain its loose, fibrous form and used as a fabric, or it may be adhered to gauze or similar material to provide strength and used as a fabric or it may be used by itself as an improved absorbent media.

In accordance with the present invention pieces of woodpulp board and air fed to the center of a pair of counter-rotating discs and are forced outwardly between the discs to the outer perimeter thereof. The surface of the discs are so designed as to separate the pieces into individual fibers and the individualized fibers forced out from the peripheral edge of the discs both by the mechanical forces caused by the discs and the force of the air flow through the area between the discs. Substantially immediately on leaving the discs the individualized fibers are conveyed away from the discs at substantially right angles thereto by means of air and collected in an air stream. The fibers are maintained in a turbulent air stream and conveyed in this form to a collecting means. The fibers are substantially uniformly distributed throughout the air stream. The velocity of the air stream is reduced without substantially disrupting the path of the flow of fibers and the fibers are substantially immediately collected on a collecting means while allowing the air to pass through said collecting means.

It is important that the feed to the refiner or mill be uniform. The pieces of woodpulp board should not only be fed uniformly, but should be substantially uniform in size, have a uniform degree of compression within a piece as well as from piece to piece and have a substantially uniform moisture content. The pieces should not have fibrillation at their edges. It is preferred that the pieces have a predetermined size dependent on the construction of the refiner. They should not be so large as to clog the refiner and not so small as to cut any substantial number of the short woodpulp fibers.

The pulp board fed to the refiner or mill should have a density of from about 0.4 gram per cubic centimeter to about 0.7 gram per cubic centimeter and preferably from about 0.55 to 0.65 gram per cubic centimeter. Too high or too low a density makes the board very difficult to separate into individual fibers and very often will cause excess fiber breakage.

In attempting to continuously form a uniform layer of loose woodpulp fibers the fiber fiow must be continuous and as uniform as possible. Such uniformity is of course enhanced by starting with a continuous uniform feed but is unexpectedly enhanced by feeding compressed pieces containing a plurality of fibers rather than opened or partially opened clumps of fibers.

The disc refiner or attrition mill comprises a pair of counter-rotating discs in face to face relationship, the woodpulp to be individualized is fed through the approximate center of one of the discs into the area between the discs and is forced outwardly in more or less radial paths between the discs. The individual fibers are discharged peripherally about the disc assembly. Our improvement comprises placing air forces across the periphery of the discs at substantially right angles to the outward radial flow of the fibers from the periphery of the discs. This may be accomplished by shrouding the discs with a suitable metal or other enclosure having an opening on one side of said enclosure substantially in line with the outer periphery of the discs and an outlet on the opposite side and placing the enclosure under a differential pressure from inlet to outlet.

As the fiber-air mixture is removed from around the periphery of the discs, it is collected by suitable duct work and conveyed, maintaining the air-fiber mixture in turbulent form to a collecting means. The air-fiber mixture may be retained in turbulent form by placing suitable bafiles in the duct work to maintain the turbulent flow. Flexible, corrugated tubing, wherein, the entire surface is scalloped uniformly has been found Suitable for maintaining the turbulent How of air-fiber mixture to the collecting means.

The collecting means generally comprises a foraminous surface such as a drum or conveyor to which the air-fiber mixture is directed with the air being allowed to pass through the openings in the collecting means and the fibers collected on the means. It is important that when conveying the fibers to the collecting means that the velocity be substantially constant and hence, the conveying means of a substantially constant cross-section. Furthermore, because it is desired to maintain the fibers separated the concentration of fibers in the air stream should be quite low. The minimum amount of air required to maintain a pound of woodpulp fibers separated is about 150 cubic feet. It is preferred that from about 250 cubic feet to 350 cubic feet of air be used per pound of fiber. Much larger quantities of air may also be used though the more air used the more energy required to convey the pound of fibers and the less economical the system.

To form a batt of any thickness the amount of air which has to pass through the collecting means must be high and with a constant cross-section conveying means there will not be suificient open area in the collecting means to allow all of the air to readily pass through and deposit fibers. Instead the air will bounce off the collecting means and immediately disturb fiber distribution on the collecting means.

We have now discovered a method for continually collecting the fibers from the improved air-fiber stream by increasing the cross-sectional area of the conveying means Without disturbing the fiber distribution. This is accomplished by conveying the air-fiber mixture in a duct having a rectangular cross-section to a moving foraminous collecting means, and flaring or diverging the leading and trailing edges of the duct a total of from about 50 to 80 from their parallel planes. The leading edge must be flared from about 1.4 to 3.5 times as much as the trailing edge. The distance over which the leading and trailing edges are flared must be less than three (3) times the distance between the leading and trailing edges at the point where they start to diverge. It is believed that the limitations previously described allow the inertia of fiber to maintain the fiber within the projected area of the cross-sectional area of the turbulent higher velocity conveying means until the fiber meets the collecting means and allows a portion of the air with substantially no fibers being dispersed therein, to pass both forwardly of and rearwardly of the area of the collecting means on which fibers are being deposited to pass therethrough without disruption of the fiber lay.

This of course is only a suspected theory. It may also be that by placing a vacuum beneath the collecting means to hold the fibers in place when deposited the excess air is allowed to bounce into the expanded opening and be removed without fiber disruption provided the opening is constructed in accordance with the limitations previously given.

The large volume of air at relatively high velocity, it is believed, packs the fibers into the layer as the layer is being formed. The packing of the fibers causes interlocking of fibers forming a uniform, integral sheet which is readily handleable for further processing.

In the accompanying drawings and the following specification we have illustrated and described preferred designs of machines and modes of operation embodying our invention, but it is to be understood that our invention is not to be considered limited to the constructions or operaions disclosed except as determined by the scope of the appended claims. In the following drawings,

FIGURE 1 is a diagrammatic showing, in elevation, of a preferred embodiment of fiber separating, converging and collecting apparatus suitable for carrying out the method of the present invention.

FIGURE 2 is an enlarged cross-sectional view of the improved fiber individualizing member portion of apparatus according to the present invention.

FIGURE 3 is a sectional front view of the apparatus of FIGURE 2 taken along line 3-3.

FIGURE 4 is an enlarged cross-sectional view of the improved collecting portion of the apparatus of the present invention, and

FIGURE 5 is a cross-sectional view taken along line 5-5 of FIGURE 4.

Referring to FIGURE 1 in the drawings there is shown apparatus for carrying out my improved process according to the invention. Pieces of woodpulp board, or woodpulp fibers in similar form, which are to be separated, are fed to the chute 10, through the opening 11 and between a pair of counter-rotating discs 12 and 13. Though it is preferred that the discs be counter-rotating, a combination of a stationary disc and a rotating disc may also be used. The force caused by the rotating discs forces the separated fibers out through and between the surfaces of the discs to the outer periphery 14 of the discs. The separated fibers are forced into the open space 15 enclosed by a shroud 16. The shroud has a circular opening 17 approximately in line with the outer circumference of the discs and the shroud is connected to the intake 18 of an air blower 19 for pulling a vacuum in the shroud. In operation, air is drawn through the circular opening in the shroud and directed perpendicular to the fibers being forced out from the rotating discs, and the fibers are drawn by suction into the intake of the fan or blower. The air-fiber mixture is blown by the blower to the depositing portion of the apparatus. The mixture is conveyed from the blower to the depositing section through corrugated type duct work 23 which maintains the entire air-fiber stream in highly turbulent condition and prevents fiber agglomeration as the air-fiber mixture is being conveyed. The depositing section comprises a condensing mechanism 24 connected to the conveying duct work by suitable conduit 25 in accordance with the present invention. The condensing mechanism is a rotating perforated drum 27, which passes over a stationary vacuum slot 28. The vacuum slot is in line with the conduit 25 and the drum rotates in the direction of the arrow shown.

The cross-sectional area of the duct 23 is kept constant. At point A the cross-sectional area changes from a round configuration to a square configuration and is main tained constant to point B. At point B the configuration may be changed until point C in order to obtain the desired width of fiber lay. For example, two sides of the square conduit may be converged while the opposite sides are diverged in order to lay a wider sheet on the surface of the drum, however, when so doing the cross-sectional area of the conduit is maintained essentially constant. It is important that when changing cross-sectional areas the air velocity be kept at a minimum of 3,000 feet per minute.

At point C immediately adjacent the surface of the drum, the cross-sectional area is expanded in a specific manner to allow the air to expand and have suflicient area to pass through the drum without disturbing the fiber flow. In order to accomplish this the area must be expanded in the direction of rotation or direction of movement of the condensing means to a greater degree than in the opposite direction and it should preferably be at least expanded twice the amount in the direction of movement as it is in the direction opposed thereto. Furthermore, this expansion must be accomplished over a distance such that the expansion does not overcome fiber inertia and the fiber rather than being moved outwardly from its line of flow, has sufficient inertia to carry it in approximately a direct line to the condensing means. This distance should be 8" or less and preferably 6" or less.

The fibrous layer is removed from the condensing means by a doctor blade 30 and passed to a suitable conveyor means 31, to be processed as desired. Air may also be used to remove the fiber layer from the condensing means.

In FIGURES 2 and 3 of the drawings there is shown an enlarged view of the disc refining means in accordance with the present invention. This means comprises a pair of

shafts

35 and 36 which are in line and spaced a short distance apart. On the respective shafts there are mounted

discs

37 and 38 with the faces of the discs in face to face relationship. The discs are mounted on the shafts by means of screws 40 so that the discs rotate with the shafts. The rear disc 38 is solid and has a smooth face 41 approximately half way out its radius. The outer portion of the disc has a grooved surface 42. The exact configuration and size of these grooves will depend upon the fiber being processed, the speed of processing, moisture, kind of grinding and the desired amount of attrition force to be applied to the fibers while processing. The front disc 37 has three equally spaced openings 44 around the disc extending from its approximate center hub about half way out its radius suitable for feeding pieces of pulpboard through these openings into the space between the two discs. Rectangular shaped compressed pieces of woodpulp having inch to /2 inch long sides have been found suitable for feeding the disc refiner. The outer portion 43 of the surface of the front disc also has grooves in face to face relationship with the grooves of the rear disc. These grooves may also have any desired configuration dependent upon the type of fiber being processed and the attrition force desired. The two discs are encased in a suitable shroud 45 of metal or similar material. There is an opening 46 in the shroud corresponding to the area of the openings in the front disc. This shroud opening leads to a funnel 47 through which the pieces of woodpulp may be fed by gravity or forced by air pressure through the funnel into the opening in the shroud and through the openings in the front disc into the area between the discs. The attrition force of the discs forces the woodpulp between the grooved faces of the discs shredding the woodpulp board and separating fibers. The fibers pass out about the periphery of the discs.

The shroud has opening 50 for connection to suction means. This opening is positioned in the shroud so as not to be in line with the fiber being thrown from the periphery of the discs. The shroud also has a circular opening 51 positioned on one face thereof to draw air across the periphery of the discs. This opening should be of such a size and configuration that it draws air uniformly across the entire periphery of the discs. For example, as shown in FIGURE 2, the opening is narrower at the point closest to A and widest at the point furthest removed from A and is graduated between these two points as is shown in FIGURE 3.

In operation as the separated fibers are being forced from between the faces of the disc, the air flow is substantially perpendicular to the direction in which the fibers are being forced by the discs, causing the fiber to be immediately moved from the area directly about the periphery of the discs and preventing the formation of fiber agglomerations.

Though a particular configuration is shown in FIG- URES 2 and 3 the important points are that in the shroud about the rotating discs the air outlet should not be in line with the directional force applied to the fibers by the discs and the air inlet must be substantially perpendicular to the direction of flow of fibers from the disc.

Once the dispersion of the individual fibers in air is accomplished it is important that this dispersion of individual fibers be maintained in such form until the fibers are disposited in the desired configuration such as a loose, open layer of fibers. To convey the air-fiber dispersion and prevent agglomeration or neps forming in the dispersion the conveying means should have a smooth surface. We have discovered that not only must the smooth surface be present, but this surface must not be straight, but in such a configuration as to maintain the turbulent condition of the air-fiber stream throughout the cross-sectional area of the conveying means. A corrugated, scalloped, or sine wave surface maintains the airfiber dispersion turbulent throughout its entire flowing pattern and unexpectedly the fibers flowing through this corrugated duck work do not agglomerate but maintain their individual form and may be deposited in a very uniform layer without neps or blotches of fibers.

The amount of suction applied in the shroud surrounding the disc refiner may be from about 12" to 14" of water vacuum. The opening to the shroud if in the configuration of a circular band should have a width of about A".

In the disc refiner the setting of the discs and the type of disc used, will depend upon the type of fibers being processed and the amount of fibers processed. If desired, the fibers may have a finish on them to improve their processing. The particular finish found useful when shredding woodpulp fibers is a lubricating compound, such as, oleyl imidazoline salt. It appears that such compounds act as a softener, lubricant and has an antistatic effect. Such lubricants are especially important if it is desired to form lightweight layers of woodpulp fibers where fiber distribution is most critical. Rather than using an antistatic compound the static may also be eliminated by maintaining the desired humidity in the airfiber dispersion. It is believed that the eddy currents set up at the periphery of the refining discs are minimized by forcing air substantially across the mouth of the discs and the fibers are maintained in individualized form rather than being agglomerated by the eddy currents.

Though suction has been described air pressure may also be utilized, and though the fiber-air dispersion has been removed from about the discs in a downward pattern, it may also be removed in an upward pattern or other pattern as desired.

In feeding the discs it is important that the feed not plug or clog the openings to the area between the discs. As shown in FIGURE 2 the block 52 directs the flow from the chute upwardly and against the rear disc to prevent clogging or plugging either in the opening or between discs.

The velocity of the air-fiber dispersion may be from about 6,000 to 8,000 feet per minute so when presented to the condensing means, there is a considerable volume of air, which unless removed uniformly, will disrupt the fibrous layer as it is laid on the condensing means. Referring to FIGURES 4 and 5, there is shown our im proved fiber laying apparatus. The fibers in sheet form of the desired width are collected on a perforated moving surface 60 such as a perforated drum or a perforated conveyor. Beneath the surface is a suction conduit 61 for collecting the air. The fibers filtered out by the surface are formed into a sheet 62. The thickness of the sheet will depend upon the speed of the surface and the concentration of the fibers in the dispersion. The duct work 63 feeding the surface is kept at a substantially constant cross-sectional area. This cross-sectional area 64 is generally circular or square and is expanded in one direction and contracted in the other direction to form a lay of the desired width while maintaining the cross-sectional area uniform. For example, if a 6" square duct 64 is being used

opposite sides

65 and 66 are converged while the other sides 67 and 68 are diverged in such a manner as to maintain a constant cross-section until the width of the lay is 12" wide, if this is the width of the desired fiber sheet, and the other dimension would be 3". In diverging the sides it is important that they be diverged at a total angle 20: of less than 20 and preferably less than to prevent turbulence and conglomeration of the fibers. The sides should be diverged an equivalent amount so that each side diverges from the vertical from about 7 to 10, angle a.

Once the desired cross-sectional configuration is obtained as at E and within 8" of the condensing surface the front and rear surfaces 70 and 71 respectively are expanded to provide for a larger area for removal of air. The front surface should be expanded at least twice the degree that the back surface is expanded. This expansion allows the air to expand and be removed over entire area F of the condensing means while the inertia of the fiber causes the fiber to continue in its same motion and be deposited uniformly.

As shown in FIGURE 4 the front angle B should be less than 55 and preferably less than 45, whereas, the rear angle 1' should be less than 30 and preferably less than The distance from the start of the expansion B to the condensing means must be less than 8" and should be approximately '6". The rear wall of the transition chamber should be expanded from about 15 to from the vertical in a negative direction, whereas, the front wall should be expanded from about to 55 in a positive direction from the vertical, the total expansion should be less than 80 in order to obtain the advantages of the present invention. If there is not sufiicient open area for the air to be removed while the fibers are being filtered the fibrous lay will be greatly disrupted. If too great an area is provided the velocity of the air-fiber mixture is reduced and the fibers will tend to agglomerate and form non-uniform areas in the layer.

For the sake of clarity standard items have been omitted from the drawings; e.g., the necessary blower for producing a vacuum in the conduit or slot 28, the various standard vacuum seals required throughout the apparatus to prevent blow-out of fibers, etc.

Although the invention has been described in specific detail and with certain structural characteristics, the same should not be construed as limited thereby, nor to the specific details mentioned therein, but to include various other equivalent constructions as set forth in the claims appended hereto. It is understood that any suitable changes, modifications, and variations may be made without departing from the spirit and scope of the invention.

What is claimed is:

1. A method of individualizing woodpulp fibers comprising feeding substantially dry woodpulp board to the center of a pair of counter-rotating discs, causing the pulp board to pass radially outward between the discs whereby the board is separated into individual fibers and the fibers discharged from the periphery of the discs and causing air currents to flow uniformly across the entire periphery of the discs and substantially perpendicular to said periphery to immediately remove fibers from about the periphery of the discs and maintain the fibers in their individual form.

2. A method according to claim 1, wherein, the fibers removed from about the periphery of the discs are conveyed from the proximity of the discs by means of a turbulent air stream.

3. A method according to claim 1, wherein, the woodpulp board has a moisture content of from about 3 to 6 percent by weight and the individual fibers have 2. moisture content of less than 16 percent by weight.

4. A method according to claim 1, wherein, air currents are caused to flow substantially uniformly across the entire periphery of the discs to immediately remove fibers from about the periphery of the discs and the removed fibers are conveyed from the proximity of the discs by means of a turbulent air stream.

5. A continuous method for forming a loose open layer of short fibers, said fibers having a length of A inch or less, from dispersions of such fibers in air comprising conveying said air-fiber dispersion at a substantially constant velocity to a continuously moving permeable forming surface, immediately adjacent said forming surface reducing said velocity by increasing the area of air flow without increasing the area of fiber fiow said increase of area of air flow being greater in the direction in which said forming surface is moving than in the direction op posed thereto to maintain the fibers within the projected area of the constant velocity cross-sectional area until the fiber meets said forming surface with substantially no fibers being dispersed within the increased portion of the area of air flow and passing the reduced velocity air flow through said forming surface while fibers are collected on said surface in the form of a uniform layer of short fibers.

6. A method of individualizing woodpulp fibers and collecting such fibers in the form of a loose open layer comprising feeding substantially dry woodpulp board to the center of a pair of counter-rotating discs, causing the pulp board to pass radially outward between the discs whereby the board is separated into individual fibers and the fibers discharged from the periphery of the discs, causing air currents to flow across the periphery of the discs and substantially perpendicular to said periphery to immediately remove fibers from about the periphery of the discs in the form of a dispersion of individual fibers in air, conveying said air-fiber dispersion at a substantially constant turbulent velocity to a moving permeable forming surface, immediately adjacent said forming surface reducing said velocity by increasing the area of air flow without increasing the area of fiber flow said increased area of air flow being greater in the direction of movement of said forming surface than in the direction opposed thereto to maintain the fibers within the projected area of the constant turbulent velocity cross-sectional area until the fiber meets said forming surface with substantially no fibers being dispersed in the increased portion of the area of air flow and passing the reduced velocity air flow through said forming surface while fibers are collected on said forming surface in the form of a uniform layer of woodpulp fibers.

7. A method according to claim 6, wherein, the woodpulp board has a moisture content of from about 3 to 6 percent by weight and the uniform layer of woodpulp fibers has a moisture content of less than 16 percent by weight.

8. A continuous method according to claim 6, wherein, the woodpulp board is fed at a substantially constant rate to the discs in the form of pieces of board of substantially uniform size, having a moisture content of from about 3 to 6 percent by weight and having a density of from about 0.55 to 0.65 gram per cubic centimeter.

9. Apparatus for individualing fibers, having a length of A inch or less, from fibrous material comprising a pair of counter-rotatable discs in face to face relationship enclosed in a shroud, means for feeding fibrous material to the center of and between the discs for outward radial movement and peripheral discharge from between the discs and into the shroud, said shroud having an uninterrupted opening positioned adjacent the periphery of the discs for flowing air across the periphery of the discs and substantially perpendicular thereto.

10. Apparatus according to claim 9, wherein, the shroud has an outlet connection, said outlet being out of line with the periphery of the discs and connected to suction means for drawing air and fiber from said shroud.

11. Apparatus for individualizing fibers, having a length of inch or less and collecting such fibers in the form of a loose open layer comprising: a pair of counterrotatable discs in face to face relationship and enclosed in a shroud, means for feeding fibrous material to be individualized to the center of and between the discs for outward radial movement and peripheral discharge from between the discs and into the shroud, said shroud having an uninterrupted opening positioned adjacent the periphery of the discs, means for flowing air across the periphery of said discs substantially perpendicular thereto and removing fibers and air from said shroud and conveying said air and fibers are an air-fiber dispersion, a conveying duct having an undulating configuration along its length for maintaining a turbulent velocity of said air-fiber dispersion, a permeable moving forming surface adjacent the end of said duct for collecting fibers in the "form of a layer and closing air to escape, and dust being connected to said forming surface by a transistion piece of increasing cross-sectional area.

12. Apparatus according to claim 11, wherein the shroud has an outlet connection out of line with the periphery of said discs and connected to the means for flowing air.

13. Apparatus according to claim 11, wherein, the conveying duct is corrugated, flexible, piping.

14. Apparatus according to claim 11, wherein, the transition piece has a rectangular cross-section of increasing cross-sectional area, 2 opposed sides being substantially parallel and vertically in line with the sides of said moving surface while the other 2 opposed sides diverge from each other at a total angle of 50 to 80 degrees, the leading edge diverging about 1.4 to 3.5 times as much as the trailing edge with the edges extending across the width of said moving surface.

15. Apparatus according to claim 14, wherein, the distance over which the cross-sectional area of the transition piece increase is less than 8 inches.

16. Apparatus according to claim 11, wherein the transition piece has a rectangular cross-section of increasing cross-sectional area, 2 opposed sides being substantially parallel and vertically in line with the sides of said moving surface while the other 2 opposed sides diverge from each other, the leading edge of said transition piece being flared from about 35 to 55 towards the direction of movement of the surface and the trailing edge being flared from about 15 to 25 away from the direction of movement of the surface, with the edges extending across the width of said moving surface and the distance over which the cross-sectional area of the transition piece increases is less than 8 inches.

17. Apparatus for individualizing fibers, having a length of inch or less and collecting such fibers in the form of a loose open layer comprising: a pair of oppositely rotatable discs in face to face relationship and enclosed in a shroud, said casing having an air inlet and an air outlet, means for feeding fibrous material to be individualized to the center of and between the discs for outward radial movement and peripheral discharge from between the discs and into the shroud, said air inlet being substantially in line perpendicularly to the periphery of said discs, said air outlet being out of line with the periphery of the discs, said air outlet being connected to the suction side' of an air blower, the discharge side of said air blower being connected to a moving permeable forming surface by means of a flexible, corrugated duct one end of which is directly attached to said discharge side and the other end attchade to a transition piece positioned directly above said moving permeable forming surface, said transition piece having a rectangular crosssection of increasing cross-sectional area, 2 opposed sides of said transition piece being substantially parallel and vertically in line with the sides of said forming surface while the other 2 opposed sides diverge from each other, the leading edge of said transition piece being flared from about 35 to towards the direction of movement of the forming surface and the trailing edge being flared from about 15 to 25 away from the direction of movement of the forming surface with the edges extending across the width of said forming surface, and the distance over which the cross-sectional area of the transition piece increases being less than 8 inches.

References Cited UNITED STATES PATENTS 845,721 2/ 1907 Sovereign 241-- 1,380,112 5/ 1921 Middelroe 241-60 2,807,054 9/1957 Burger et al 19l56.3 2,937,815 5/1960 Eirich et a1. 24160 3,268,954 8/1966 Joa 19-156.3 3,133,318 5/1964 Neubauer 1980 FOREIGN PATENTS 132,427 1933 Austria.

DORSEY NEWTON, Primary Examiner 22 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, +75,79 Dated y 9 7 Inventor(s) Charles A. Brewster et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

r- Column IO, line 7, Claim 17, the word "casing" should read --shroud--.

QIUHLU Aflu SEALED FEB 1 7-1970 @EAL) Axum:

EdwudM-F m mm WILLIAM E. 50mm. m.

Atteating Officer Commissioner of Patents