US2940133A - Continuous deposition of dry felted structures - Google Patents

Description

June 14, 1960 c. c. HERITAGE CONTINUOUS DEPOSITION OF DRY FELTED STRUCTURES Filed April 14. 1950 2 Sheets-Sheet 1 June 14) 1960 c. c. HERITAGE 2,940,133

CONTINUOUS DEPOSITION OF DRY FELTED STRUCTURES Filed April 14, 1950 2 Sheets-Sheet 2 CONTINUOUS DEPOSITION OF DRY FELTED STRUCTURES Clark C. Heritage, Minneapolis, Minn, assignor of onehalf to Weyerhaenser Company, a corporation of Washington, and one-half to Wood Conversion Company, St. Paul, Minn, a corporation of Delaware Filed Apr. 14, 1950, Ser. No. 156,018 15 Claims. c1. 19-156) The present invention relates to the continuous production of felted fiber products by a dry process, and in particular to the production of one or more continuous webs, and one or more continuous streams of individual felted entities, for example small pads.

The production of air-laid fiber felts by deposition of fibers from suspension in air is attended with difficulties which become more pronounced as the objectives of uniformity and high quality of the felt are increased. Dry vegetable fibers, especially the shorter fibers derived from wood, are kinky and consequently tend to entangle and clot as they encounter each other in air suspension. In attempting to secure a high rate of production in forming air-laid felts, common expedients are to increase the fiber concentration in the air, and to increase the rate of flow of the air suspension. In particular the increased concentration tends to induce flocking. The longer the path of travel of an air suspension, the greater are the opportunities for mutual encounter of fibers and hence of clotting. Also, the impinging of the suspended fibers on conduit walls, both straight runs and turns, enhances the clotting. Thus, the deposition of clots instead of or along with individual fibers leads to poor formation and undesirable inequalities throughout the felt.

The present invention employs apparatus and process for forming felts from air-suspended fibers at a high rate of production, with a minimum of clotting, and with variability in the nature of the felts.

It is a general object of the invention to provide a continuous process of felting to produce either a continuous felted web, or a continuous stream of separate felted entities.

It is a general object of the invention to employ superatmospheric pressure on the felting side of a felting screen, and subatmospheric pressure on the other side of the screen.

It is a general object of the invention to form the fiber felt on a cylindrical screen and thereby provide a convex surface to cooperate with a loop of sheet material which may be employed in the process for one or more functions.

It is also an object of the invention to form felted bodies containing non-fibrous material in finely divided form, by a continuous process involving constancy of proportion in the infed materials, and recirculation of fines which escape from the felt. Various other and ancillary objects and advantages of the invention will become apparent from the following description and explanation of the presently preferred manner of carrying out the invention, as shown in the accompanying drawings, in which: 1

Fig. 1 is a diagrammatic layout of the process and up paratus therefor.

atent' O i Fig. 2 shows a felting cylinder of which the peripheral area is in part blocked off by peripheral non-filtering bands to provide a plurality of parallel strips of felt.

Fig. 3 is a modification of the screen cylinder of Fig.

2 in which the several peripheral screen areas for forming 2,940,133 Patented June 14 1960 2 a strips are divided by cross-bands of blocked'areas thus to divide the strips into a succession of felted entities.

First, there is provided means for continuously formingan air suspension of substantially individualized fibers, which is such a means as to permit the reintroduction of fines which escape through the felt and the felting screen, in order to recycle the fines without accumulating a loss of material. The primary objective is to deliver the suspension to a depositing area, and this may be effected by the positional relation of parts. However, to this end there may be, and preferably is, provided'a nozzle like conduit means for delivering the air suspension, which means may readily be designed to minimize clotting and to deliver a uniform and continuous supply of dispersed fibers to and over a depositing area at which a felt is deposited by filtering the fibers from the air suspension. Then there is employed a rotating cylindrical filtering or felting screen which presents felting screen area substantially exposed in said depositing area,'with permissible blocked-off or blank non-filtering area where division of the felt structure is desired, such as division into'continuous bands or one stream or more of separate bodies :of felts. Associated with the cylindrical screen is means for exerting suction under thescreen at an-area including the depositing area, to assist in forming the felt entire screen and to collect the fines. which pass through thefelt and the screen. Before the formed felt on the cylindrical screen has an opportunity to become detachedfrom the screen, means is provided which may be employedto wrap a continuous web of sheet material over the face .of the felt to travel with it to anew position where it'functions after removal of the felt'from the screen. i a

The means for providing a stream of air-containing suspended fibers at superatmospheric pressure may be of numerous kinds. The preferred method is illustrated in Fig. l. Fibrous material 10, such as pulp laps or other bulk forms of fibrous material to be individualized for dispersion, is fed at a controllable rate into a hopper 11 which leads to a mill12 of suitable character todisintegrate the supplied fibrous material into a mass of substantially individualized fibers, clottedor not, and in high concentration preferably in the form of a fiulf. The mill may be one of conventional type for thepurpose, such as a hammer-mill having a cylindrical casing 13, an arcuate portion of which is perforated as indicated at 14, through which portion the disintegrated material is discharged as fiber into a receiver 15. The mill has a coaxial rotor 16 which has vanes or other means such as swinging hammers 17 so arranged that in rotation of the rotor the hammers effect disintegration of the fibrous material 19, and also movement of it through the perforated screen portion 14. Such a mill is commonly associated with means to cause a current of air to flow through it. As shown in the drawings, the receiving chamber 15 is connected tightly'over the plate 14 and also connected to the suction side of a blower 20 which discharges through conduit 21 to a cyclone 22. Thus, in operation the fibrous material 10 is disintegrated into a material which may be discharged as a fluff into said cyclone 22 along with vehicular air drawn in whole or in part from the atmosphere at the hopper 11 by action' including that of the blower 20.

The cyclone 22 functions to separate air and the fiber or fiuflf, discharging the air upwardly through a top vent 23 for exhaust. For'numerous reasons of economy, part i of the air so vented through the top portion 23 may be 7 base, preferably as a supply of accumulated fiber of variable depth to accommodate irregularities in the feed,

ingaoflfiher .10.into hopper 11.; Beneath. the cyclone is an endless conveyer belt 28 which gathers on it fiber 29 as the belt passes under the lower end 25 of the cyclone.

'Breferablyrthe belLis .operatedat a co ntrolled rate and 'is arranged .tdcarry ,a:mcasured,amount ot fiber in a given time,.thus allowingQa reserve supply to'be maintaine'd jnithe bottom;.25. of thecyclone. Ihe measured amountinaynbe controlled byregulating the distance between; tlm'discharge opening 25 and the 'conveyer belt 28, and also by; regulatmg, the rate of travel of the belt 2%.

;. The/arrangement described permits the feed from the 'conveyerhelt 23. of substantially indiridualized fibers 7 inrflufitformataaregular .rate,,-for dispersal anddeiivery V V 'xr'ilthezfelting'nieans, Thedispersal in .air. for felting is ifiected. hynaz finakdisper'ser which frnay be generally of the same type as. the primary vdisperser}; Modifications,

however, Lare,'indicated. .As a final. disperser there is shown :1 cylindrical casingSfl ona horizontal axis, having amarcuate extent ofiits periphery, namely about 90, perforated as a screen-31, through whichfibers are urged hy operation of the disperser. There is an agitator in the casingapreferably provided as a co-axial rotor 32 which Ernay operate at'high. speed; and therebyact as a sort of fan orblower to inducea flow ofairoutwardly through the. casing to discharge; at superatmospheric. pressure through the screen 31; In the event the agitator does not encompasses the semen 'iarea; particularly to the peripheral directions; than to the lat- 'eral bounds. Arcuate dampers '44]: team; are adjust- On the external tace ot the disperser 1 3 0 is a collecting hood or nozzle 38 haying a special construction. It is so formed as to have two diverging horn-like sections, leading to the edges of the perforated plate 31 'of the disperser, thus tofgat firthe air suspension coming through screen '31 aud'harrowing the passageway increasesas it moves awayj from the screen. By this means clotting is minimized by a tendency to moveeach fiber faster than each reuowin sber wherejhere" are the side walls 6f the horns tending wineries clotting. This censtnetien er ne ress-secede er. the stream is carried to the depositing area where the felt is formed, by the slight'taper' of the nozzle 38.

The felting meansjis' provided as a cylindrical screen of which a screen periphery 40 moves at a regular rate through a depositing area 41 which in the illustrated embodiment is the orificeof the nozzle38... The character of the screen niay be greedy modified as will :be

describedihereinaften but for simplification of the-description it may be said that the screen 40 in Fig. 1 is entirely perforated without obstructing areas. Thus, on the screen 40 a continuous webmay be-formed having a width from edge .to edge of the orifice of nozzle 38'. Such a web is indicated by. the numeral 42 as it leaves the depositing area 41 passing under the edge 43 ofthenozzle38 1 V Associated with the screen" 40 is a suction boir beheath-the depositing area 41 as indieated' byithe nemeral 44; The examiner" .or'the suction BQX is prefir'nuin liesoutsidevof and th. reference more erably variable, and time able to" control the peripheral dimension of the suction opening. Thesuction box '14 connects bys'uitabl e and is indiciat'ed' orlongitudinally-or fadewise, if means tor obtaining the desired flow of air'and flufi' is provided'a's mentioned above. Leading to the opening -35 is a hopper 36 open-to the atmosphere-into which the conveyer belt 2 8-discharges 'its load of fluif alongside air drawn into the a hopper from the atmosphere bythe suction applied there 7 =10, which air enters as a fiber-free portion of-the' current .ofair foi depositing the fiben V heral extent of the screen 31 in part pre 7 determines the direction'and characterof the discharged.

air s'uspension of fiben. The next step is to pass the stream-of air:and fiber through a screen to form a felt. This place of formation is called herein a depositing .area and its location predetermines the path of a moving screen: on which the felt is formed. To assist the deposi- V "tion suction is applied under the screen, Whereas the .air stream in fhe depositing area is at super-atmospheric press-urew The suction capacity is such as to take in all air constituting the current which carries fibers into tti'e depositing area, in order to prevent escape of fibers nndairirom the depositing area into theatmosphere. -Consequently the area of the screen at which suction is .appliedincludes the entire depositing area Within its bounds, and preferably the suction area is greater than "the depositing area to draw in atmospheric air as a sort of envelope'to house theair'suspension; V V

. Toithe'se ends, -the screen 31.61; the'final; disperser may be placedvery close "to the depositing area, or be remote fromitwhen suitable means is employed to confine the current of air discharged at the screen 31 and directit toward or" to the area. Because. of {he'wide angle comprehended the particularly illus trated''scree'ri-31';-such a1 "confining means is employed iiaoiting' area: Y

well-known structufethrough -the 212516 45 to a suction conduit 46- leadingto the intake 'of blower 4.7 which discharges via c onduit48'to al cyc lone 49. ,Tl'ie blower 47 is operated so that it ten'ds to draw in more through the suction box that i s sup'plie'dto the depositingarea 41 through nozzle eas the operation of disperser-30,

that is, at least all the air newness. and preferably an additional amount from the atmosphere As a result the upper side of the depositin'g area is at superatmospheric pressure,,whi le the lower side within the cylinder 40s; at subatmo'sphericpres'sure; The consequence is that the felting zone itself is at substantially atmospheric. pressure, tthus to facilitate mechanical construction and perafien; By operation to draw in exactly the same amount of into .su'tid box 44 as flows to the depositing area from the disperser 30, no. leakage of suspended fibers from the nozzle to the atmosphere will result. .Howevenfsuch a balance is dii'ficult' for practical nianag'ement and .it is 7: therefore preferred that the blower 47 be operated to draw in somejair from the through. thefelt andthe felting screento enter the exin; the apparatus of the drawin gslflsince thejdistance tit iveirsedfrorn screen to the-depositing area is also V 'pi'ferabl y ShlQ flt; said confining means is extended asortot conduit or nozzle substantially'to the de haust system, comparable. to the fibrous content in the white water in making paper onf 'conventional, paper- .making. machines. Since the present apparatus and process may also be operated to include material other ftha n' fiber, for example;fiuelywdivicledresin powder to "serveas a bond, later described, some. of thispowdcr willalso escap Being frequently the more expensive component stare felt to be'forined; such a resin powder must be used in fin subdivision "for ethciency. This enhances loss of it into the exhaust and-makes more importantthe necessity to save thesolid entrained eomponents of the exhaust. This is effected in the cyclone 49.

Cyclone 49 is of the same general type as the cyclone 22, but its operation is somewhat different. Cyclone 49 vents to the atmosphere by way of conduit 51 at the top, which has an adjustable damper 52. Changing the set of the damper controls the amount of air discharged via vent 51, and compels the remainder to escape through the bottom 53 of the cyclone 49. In operation the cyclone thus effects a separation of the exhaust stream in conduit 48 into at least two portions, one of which is air enriched with the entrained fines from the exhaust. This enriched portion escapes at the bottom 53 of the cyclone and from there it discharges or is conveyed into the hopper 36 alongside the infed fluff 29. Thus, recycling of the fines is effected and there is no loss of material.

The processing of material by the apparatus described calls for a fine adjustment in proportion between fiber and other material, for example, resin powder, and where continuous uniformity in proportion is desired in the final felt 42, it is only necessary to regulate the feed of such materials propertly to the disperser. The nonfibrous material may be fed in at hopper 11, or at hopper 36 or at any intermediate location. In continuous operation including the recycling of the fines, the original fed proportion is constantly maintained without adverse efiect resulting from the escape of fines through the filtering screen into the exhaust system.

As illustrated the nozzle 38 discharges onto the top of the rotating cylinder 40 so that action of gravity supplements the felted union of the felt to the screen to hold the formed felt 42 onto the cylinder. Before the felt 42 has an opportunity to become detached, a web of sheet material is brought to the face of the felt and combined with it by facial engagement for travel therewith. Thus, as the cylinder rotates, the felt may be held firmly to the cylinder by maintaining contact of the web with the cylinder. The sveb so introduced may vary in structure and in function. For example, it may merely be a transfer means in the form of an endless belt brought to the cylinder near the top and removed near the bottom at a position where it underlies the felt so that it is merely a vehicle to carry the felt away from the cylinder. The web may be a sheet of paper which is to remain with the formed felt, for example as a liner therefor in some subsequent combination structure. The web may be brought to the face of the felt with active or activatable adhesive applied interfacially, for example by applying such adhesive to the appropriate face of the web.

As shown there is a roll 61 near the top of the cylinder, over which passes a web of material indicated by the numeral 62. The roll may press upon the felt 42 or be spaced from it, serving primarily to position the sheet 62 so that it will wrap around the convex surface below it as presented by the felt on the cylinder. Where the web 62 bears active adhesive, as above mentioned, it is preferred that the roll 61 press upon the felt 42 in order to exert pressure for adhesive engagement at the interface.

At the bottom of the cylinder 40 the relationship of web 62 to felt 42 is such that the web underlies the felt where it may serve as a carrier to support the felt in leaving the cylinder as indicated by the numeral 64. At this point the felt 42 rests on the web or sheet 62 and the two move upwardly away, for example, at an angle for subsequent processing. In the event that the felt 42 adheres to the screen 40, it may be forced away from the screen by air pressure. For this purpose there is shown a pressure chamber 65 fed by compressed air in pipe 66. Chamber 65 opens to the inner face of the screen to blow the felt off the screen, and incidentally clean the screen. Where the felt is continuous as shown in Fig. l, the felted strength is commonly sufficient to peel the felt from the screen without the necessity to blow it from initial contact position. However, where the felt formed may be a separate entity, and not a continuouss'trip, as would result from use of the cylinder of Fig. 3, it is desirable to assist the detachment by use of compressed air. This is especially true when the said felted entity is not adhesively united to sheet 62.

Where the mat 42 is such that it contains a bonding agent, for example in the form of resin powder, which may be activated to thermoset adhesion, it is permitted that the web 62 be a screen through which and through the felt, hot air may be passed to effect heating and bond ing rapidly and without delay which would result from the transfer of heat conductively.

In Fig. 2 there is shown a cylinder which may be the same cylinder as shown in Fig. 1. The cylinder has a plurality of wide peripheral filtering bands 68 of the screen material, and between them separating imperforate bands 69 and also imperforate terminal boundary bands 70. The bands 69 and 70 may be of any suitable material, thin or thick. For example, it may be ordinary paper masking tape placed over the perforations of a full cylindrical screen to provide non-felted separations be.- tween strips of felt to be formed side'by-side on, the bands 63. The bands also may be of rubber, .or even metal. Removable masking material over a full, screen is preferred to permit varying the pattern.

Fig. 3 shows a cylinder similar to that of Fig. 2 which has terminal imperforate bands 73 and peripheral imperforate masking bands 74, substantially as described with respect to Fig. 2. Additionally there are imperforate cross-bands 75 at spaced intervals over the; screen between the circular bands 73 and 74. The bands 75 are preferably equally spaced on the cylinder so that the felt formed between any two adjacent circular bands will consist of a sequence of rectangular pad-like units of the same size. The cross-bands 75 are preferably alined with each other not only to facilitate subsequent operations on the adjacent series of the felted entities, but also to facilitate operation of the felting machine itself with respect to removing residual fibers which may be deposited on top of the cross-bands 75 as well as on the peripheral bands 73 and 74 of Fig. 3, or the peripheral bands 69 and 7 G of Fig. 2.

Although the forces tending to felt the fiber function primarily over the open screen, the felting is not completely so confined and fibers may readily deposit and loosely felt on the imperforate area, or be held partly thereover while engaged in the edge of the tighter felt which is present over the open screen area. Where it is desirable to have well defined edges of the felted strips or units formed, it is possible to clear such residual fibers from the imperforate area before the formed felt becomes facially engaged with the combining sheet 62. One way so to clean the imperforate areas is to blow the fibers therefrom by a suitable gentle current of air not sufiiciently strong to break up the desired felted condition at the edges of the primary felt. This is accomplished in one way by placing near but spaced from the periphery of the felt 42 as it leaves the depositing area 41, suitable air jets to blow the fibers away, and preferably a collecting hood over the jets and generally over the .area from which the fibers are being removed by the air jet.

In Fig. 1 such mechanism is shown in the form of a hood 89 extending lengthwise of the cylinder just above the surface of the felt at a location between the roll 61 and the nozzle 38. Within the hood are a number of compressed air pipes 81 provided with openings to serve as air jets, which openings are located at positions to blow air onto the imperforate areas of .the cylinder. The number of pipes, the locations of the jets and the operation of them, must be varied in accordance with the pattern on the cylinder. The operation of the jets to' discharge air is continuous or intermittent, but under control, according to the timing necessary to function only over masked areas. Thus, for the cylinder illus dated in 2.. bnt'one of thelpipes 81.wouldfunctioi.

and it wo uld function continuously because of thecou: tinuous'ipassage of the peripheral bands 69,under the 'c'orresponding'jetsl Wheri the cylinder of Fig. 3 is employed rather than the cylinder of Fig. 2,1 the same jets which function for bands 69 of Fig. 2 maycontinue to function for the bands74 of Fig. 3, and additionally the second pipe 81 is made. to function along its lengthas alined crossbands 75 pass underits jets. To limit the number ofipipes" in the hood 80, it is seen that the aliningof the adjacent cross-bands 75 is preferred to some other arrangement; Simple mechanical .means in the natureof an airvalve and a control therefor associated with'the' turningnof thecylinder, are readily applicable to control theain. The collecting hood 80 is connected by conduit 83 to the suction side of a small blower. 84 which discharges the exhausted material by ac'onduit 85 into the cyclone 49. This preserves the system from loss of fines in the samemannec as 'described for recycling the fines which pass through .the

filtering-screens The suction exerted by hoodfit) is V 1, The/method lwhich' sam le' continuously rotating on a'substantially horizontal axis 'a cylinder of which substantially all ofn the area is perforated. as a screen for ,filteringvfiber as feltsthereon from a suspension of fibers V in air exposed-to said cylinder, continuously drawing air through said cylindrical surface fromthe exterior tothe interior at a stationary localized deposition area which is traversed by the upper part of the surface of the cylinder not greater than the amount of air being drawnthrough in its rotation by establishing subatmo'spheric pressure a at said area, directing upon said cylinder at saiddeposition area a stream of air at superatmospheric pressure containing in suspensiontmaterial including 'feltable fibers for felting on said cylinder, the amount of air moving in said-stream being at least not, greater than the amount of air being drawn through said sereen, whereby to limit escape of suspended material from said stream to the atmosphere, dividing thestream, of air drawn through said screen into at least two portions of which one portion contains substantially all of the fines of suspended material drawn through said screen, diverting from the air streams recited theair of said portions which is substantially lacking in vfines,combiningsaid lines with a continuous supply of the material ultimately dispersed in air'for providing the above-mentioned stream which is directed toward said cylinder, applying a continuously moving web of sheet material over the felt already formed on saidcylindereand at a location, removed from said deposition area for travel of, the web with the cylinder in facialengagement with the felt thereon and for supporting the felt, and removing the web and the felt in a generally horizontal direction from the bottom of the cylinder. V

2. The method which comprises continuously rotating on a substantially horizontal axis a cylinder of which substantially all of the area is perforated as a screen for filtering fiber as felts thereon from a suspension of the surface ofrthe cylinderain its'rotation ,by establish ing subattnospheric pressureatsaid area, directing upon said cylinder at said deposition area a stream of air at superatmospheric pressure containing intsuspension mateincluding feltable fibers for felting. on saidcylinder, 7

said screen, whereby to limit escape of suspendeimaterial from saidstream to the atmosphere, dividing the streamof air drawn through said screen into, at least two portions of which one portion contains substantially all of the fines of suspended material drawmthrough said screen, diverting from the air streams recited, the air of said portions which is substantially lacking in fines, combiningsaid fines with a continuouswsupplyrof the material ultimately dispersed in airforproviding the above rnentioned strear'n which is directed toward said cylinder, applying a continuously moving Web of sheet material over the felt already formed on said cylinder near the top regionof the cylinder and at a location removed from said deposition area for travel of the web with the cylinder in facial engagement with the felt thereomandata region where said web underlies said felt in position to support the felt removing the felt and web from the cylinder for vehicular support of the felt bythewebfi a 7 I 3. The method whichrcornprises continuously feeding material including fibrous material into a continuous stream of air, conducting the mixed air and all said material tea perforated dispersing plate for passage of the air therethrough, continuously distributing all said material over said plate and reducing th'e fibrous mate rial to substantially individualized fibers, whereby ,the air passing through said plate carries the material including the individualized fibersv into suspension therein,-

'conducting the resulting suspension as a continuous stream at, supera tmospheric lpressure 'to aistationary localized depositing area which is traversed by the surface of a cylindrical'fiber -felting screen rotating on, a substantially horizontal axis applying sub-atmospheric pressure tothe underside ,of said screenat saiddepositing area in a manner to draw through said. screen all the air of said suspension and tending to draw in air from the surrounding atrnos phere outside of said cylinder, dividing the resulting stream of airrandany fines of suspended material drawn through said screen at the depositing area into at leasttwo portions of which one portion contains substzuitiallyv all of said fines diverting from the air streams recited the air of said portions which is substantially lacking in fines, combining said fines with said first-mentioned fibrous material-to, recycle the fines, and removing the felt from said cylinder.

4. The method which comprises continuously feeding material including fibrous material into a continuous stream of air, conducting the mixed air and all said material to a perforated dispersing plate for passage of the air therethrough, continuously distributing all saidrnaterial over said plate and reducing the fibrous material to substantially individualized fibers, whereby the air passing through said plate carries the material including the individualized fibers into suspension therein; directing the resulting suspension at, superatmospheric pressure at a stationary localized area which is traversed by the surface of a cylindrical iiber-felting screen rotating on a substantially horizontal axis, applying subatmospheric pressure to the underside of said screen at said depositing area in a manner to draw-through said screen all the air of said suspension and tending to draw in air from the surrounding atmosphere outside of said cylinder, dividingthe air and any fines of suspended material drawn through said screen at the depositing area intoa stream of air-substantially free from said fines and a stream of air enriched'in said fines, combined said enriched stream with 's aid first mentioned material to recycle the ln'1es, diverting the other stream from the remaining recited streams, and removing the felt from the cylinder. v I 7 5 T he method which comprisescontinuously feeding material including fibrous material into a continuous 9 stream of air, conducting the mixed air and all said material to a perforated dispersing plate for passage of the air therethrough, continuously distributing all said material over said plate and reducing the fibrous material to substantially individualized fibers, whereby the air passing through said plate carries the material including the individualized fibers into suspension therein, conducting the resulting suspension as a continuous stream at superatrnospheric pressure to a stationary localized depositing area which is traversed by the surface of a cylindrical fiber-felting screen rotating on a substantially horizontal axis, applying sub-atmospheric pressure to the underside of said screen at said depositing area in a manner to draw through said screen all the air of said suspension and tending to draw in air from the surrounding atmosphere outside of said cylinder, dividing the resulting stream of air and any fines of suspended material drawn through said screen at the depositing area into at least two portions of which one portion contains substantially all of said fines, diverting from the air streams recited the air of said portions which is substantially lacking in fines, combining said fines with said first-mentioned fibrous material to recycle the fines, applying a continuously moving web of sheet material over the felt already formed on said cylinder and at a location removed from said deposition area for travel of the web with the cylinder in facial engagement with the felt thereon and for supporting the felt, and removing the web and the felt from the cylinder.

6. The method which comprises continuously feeding material including fibrous material into a continuous stream of air, conducting the mixed air and all said material to a perforated dispersing plate for passage of the air therethrough, continuously distributing all said material over said plate and reducing the fibrous material to substantially individualized fibers, whereby the air passing through said plate carries the individualized fibers into suspension therein, directing the resulting suspension at superatmospheric pressure at a stationary localized depositing area which is traversed by the top side of a cylindrical fiber-felting screen rotating on a substantially horizontal axis, applying sub-atmospheric pressure to the underside of said screen at said depositing area in a manner to draw through said screen all the air of said suspension and tending to draw in air from the surrounding atmosphere outside of said cylinder, dividing the air and any fines of suspended material drawn through said screen at the depositing area into at least two portions of which one portion contains substantially all of said fines, diverting from the air streams recited the air of said portions which is substantially lacking in fines, combining said fines with said firstmentioned fibrous material to recycle the fines, applying a continuously moving Web of sheet material over the felt already formed on said cylinder near the top region of the cylinder and at a location removed from said deposition area for travel of the web with the cylinder in facial engagement with the felt thereon, and at a region where said web underlies said felt in position to support the felt removing the felt and web from the cylinder for vehicular support of the felt by the web.

7. Apparatus for dry felting comprising in combination, feeding means for continuously supplying dry fibrous material at a uniform rate, fiber dispersing means arranged to receive said fibrous material and operable to distribute substantially individualized fibers therefrom into a moving constant current of air at superatmospheric pressure, means open to the atmosphere for continuously admitting fiber-free air to meet infeeding fiber as at least a portion of the air forming said current of air, said current moving to a deposition area, a hollow cylinder rotatable on a horizontal axis and having felting screen area at its periphery arranged to move across said area of deposition, the screen area of the cylinder being sutficiently extensive to permit continuous passage of all the air of said current through the screen, a stationary suction box for operation at subatmospheric pressure within said cylinder opening to the screen over an area including said deposition area, blower means with a suction intake connected to said suction box for operation to move at least all the air constituting said current, means connected to the outlet of said blower means to free a portion of the air therefrom from fines of material suspended therein, and means to discharge said fines-free air to the atmosphere.

8. Apparatus for dry felting comprising in combination, feeding means for continuously supplying dry fibrous material at a uniform rate, fiber dispersing means arranged to receive said fibrous material and operable to distribute substantially individualized fibers therefrom into a moving constant current of air at superatmospheric pressure continuously drawn in part at least from the atmosphere, said current moving to an area of deposition, a hollow cylinder rotatable on a horizontal axis and having felting screen area at its periphery arranged to move across said area of deposition, the screen area of the cylinder being sufficiently extensive to permit continuous passage of all the air of said current through the screen, a stationary suction box for operation at subatmospheric pressure within said cylinder opening to the screen over an area including said deposition area, blower means with a suction intake connected to said suction box for operation to move at least all the air constituting said current, said blower means having its outlet arranged to discharge at least a part of the air to the atmosphere, 2. separating cyclone having a receiving opening for an air-suspension of solids for separating it into a stream of air substantially free from said solids and a second fraction containing substantially all said solids, said cyclone being arranged to discharge said second fraction into the said dispersing means for recirculation of said solids and being further arranged to divert said solids-free stream of air from the apparatus, and conduit means connecting the output side of said blower to the receiving opening of said cyclone.

9. Apparatus for dry felting comprising in combination, feeding means for continuously supplying dry fibrous material at a uniform rate, fiber dispersing means arranged to receive said fibrous material and operable to distribute substantially individualized fibers therefrom into a moving constant current of air at superatmospheric pressure continuously drawn in part at least from the atmosphere, said current moving to an area of deposition, a hollow cylinder rotatable on a horizontal axis and having felting screen area at its periphery arranged to move across said area of deposition, the screen area of the cylinder being sufliciently extensive to permit contlnuous passage of all the air of said current through the screen, a stationary suction box for operation at subatrnospheric pressure within said cylinder opening to the screen over an area including said deposition area, blower means with a suction intake connected to said suction box for operation to move at least all the air constituting said current, said blower means having its outlet arranged to discharge at least a part of the air to the atmosphere, a separating cyclone having a receiving opening for an air-suspension of solids for separating it into a stream of air substantially free from said solids and a second fraction containing substantially all said solids, said cyclone being arranged to discharge said second fraction into the said dispersing means for recirculation of said solids and being further arranged to divert said solids-free stream of air from the apparatus, conduit means connecting the output side of said blower to the receiving opening of said cyclone, a supply of sheet material arranged to move in the same direction as the deposited felt on the cylinder, and means to feed said sheet onto the fiber felt already formed on the cylinder and at a tlOK Appar tus for.

tion, feeding means for continuously supplying dry fibrous material at a uniform rate, fiber dispersing means arranged to receive said fibrous material and operable to distribute substantially individualized fibers therefrom into a moving constant current of air at superatmospheric pressure, meaus open to the atmosphere for continuously admitting fiber-free air to meet infe'e'ding fiber as at least a portion of the air forming said current of air, said current moving to a deposition area, a movable foraminous felting member exposed to atmospheric pressure at regions bounding, said deposition area and arranged to move continuously through saiddeposit'ion area for filte ingrfiberas a felt thereon from said current 'offair, a stationary suction box on the non-felting sideor"; said member foroperation at suba tmospheric pressure opening tofsaid member at an area including said regions and said deposition area, blower means with a suction intake connected to said suction box for operation to moveat least all the w constituting said current, means connected to the outlet of said blower means to :free a portion of the air therefrom, from fines of material suspended there, in, and means to discharge said fines-free air to the atmosphere. t V e 1 1. The method which comprises continuously moving a foraminous felting member exposed to atmospheric pressureat fired regions bouriding a deposition area for vfiltering fiber as a felt'thereon from .a suspension of fibers 7 hair exposed to said member at said deposition area,

continuously drawing air through said member at said deposition area from the felting side of the member attsaid regions from the atmosphereby establishing subatmospheric pressure at saiddepositing area and me areas of said houndingregions on the other side of said member, directingupon said member at said deposition area a stream of air at superatmospheric pressure containing in suspension material including feltable fibers for felting on said member, the amount or air moving in said stream being less than the amount of air being drawn through said member, thereby to prevent escape of suswhereby a felt is formed in and removed from said deposition area, removing entrained solids from at least as much air as is in eircess of that drawn from the depositing region, and returning at least the solids of the remainder through a region of atmospheric pressure to the suspension of said feltable fibers. V v

12. Apparatus for dry felting comprising in combination feeding means for continuously supplying dry fibrous material at a uniform rate, fiber dispersing means arranged to receive said fibrous material and operable to distribute substantially individualized fibers therefrom into a moving constant current of air at superatmospheric pressure, means open to the atmosphere'for continuously admitting fiber-tree air to meet infeeding fiber as at least a portion of the air forming said current of air, said current moving to a deposition area, a movable foraminous felting member exposed to atmospheric pressure at regions bounding said deposition area and arranged to move continuously through said deposition area for filtering fiber as a felt thereon from said. current of air, a

stationary suction box on the non-feltingdside of said. member for operation, attsubatrnospheric pressure 'open- 7 ing to said member at an area including said bounding regions and said deposition area, blower means with a suction intake connection to said suction box, means for operatiorl' of said blower to move all the air constituting said current and air from the atmosphere through said bo'unding regions, means connected to the outlet of, said blower means to free a portion of the air therefrom from charge said fines-free air to the atmosphere.

, 13. The methodio making a uniform fibrous web comrising the steps ofin 'ntairling an exce*s fs of'separated air entrainedifibers on one side 'ofa foraminous surface and with the air under positive pressure whereby both fibers and air are causedto pass in'subs'tantially uniform concentrations through the foramens, drawing air through and said fibers onto 'a moving surface having relatively small foramens by maintaining a pressure below atmos} phere on the outgoing side thereof whereby the fibers are deposited on the ingoingside as an interfelted mass, and maintaining the space between the surfaces partitioned from the atmosphere, the air drawn through said moving surface consisting of a minor fraction from the atmosphere and asmajor fraction comprising all the air from the foramiinous surface, whereby a slight inflow of air occurs from the surrounding atmosphere into and through the moving surface. to prevent fibers from being blown out into theatmosphere. w

p 14. Themethod of a uniform fibrous web com prising the steps of maintaining" an excess of dispersed material including essentially separated air entrained'feltable fibers on one side of a foraminoussurface and with the'air under positive pressure whereby both fibers and 'ir are caused to pass insubstahtially uniformconcentrations through the foramens, drawing air, through and said fibers onto a'moving's'ur'face having relatively small foran eusby maintainingja pressure below atmosphere on the outgoing sidethereofwherebythe fibers are deposited on the ingoiri'g' side as an interfeltedlmass, maintaining the space between the surfaces partitioned from the atmosphere tithe air drawn through said moviugs urface consisting of a minor fraction from the atmosphere and a major fraction comprising' all the airfirom the foraminous surface, whereby a'slight infiow ofair'o'ccurs from the sin rounding atmosphere into and through the moving surface to prevent fibers frornvbeing blown outiinto the atmosphere, dividing the material passing through said moving surface into theregion ofsub'atmospheric pressure'ontsaid outgoing side into an air fraction and aresid'ue, and discharging the air fraction to the atmosphere.

15. The method or makingauniform fibrous web comprising the steps of maintaining an excess or dispersed material iicluding essentially separated m'r entrained feltable fibers on one side of a foramino'us surface and'with the air under positive pressure whereby both fibers and air are caused to pass in substantially uniform concen trations through the foramens, mawing air through and said fibers onto'a moving surface having relatively small foramens by maintaininga pressure below atmosphere on the outgoingsside thereof whereby thefibers are deposited on the ingoing side as an interfelted mass, maintaining the space bet-ween the surfaces partitioned from the amosphere, the air drawn through said moving surface consistingof a minor fraction from the atmosphere and a major fraction comprising all the air from the foraminou's surfac e, wherebya slight inflow of air occurs from the surrounding atmosphere into and through the moving surface to preventfibers from being blown out into the atmosphere, dividing the material passing through said movingsurface into the region of subatmospheric pressure on said outgoing side into an air fraction and a residue, said air fraction consisting of an amount of air at least'equa'l to the amount being drawn through the moving surfacetrom the atmosphere, discharging-the a'ir fraction to the atmosphere, and feeding said residue to the positive-pressure side of said foraminous surface.

' Carter July 26, 190.4 OConnell ,Nov. 12, 1918 (Other references on following page) 13 UNITED STATES PATENTS Alder et a1 Aug. 15, 1922 Bachman June 24, 1930 Manning Dec. 30, 1930 Taylor Dec. 3, 1935 Aldrich July 13, 1937 Manning Apr. 4, 1939 mum 14 Manning Oct. 15, 1940 Joa May 12, 1942 Rainford et a1 Dec. 28, 1943 Clark Nov. 22, 1949 Lynam Dec. 11, 1951 Joa Nov. 25, 1952 Clark Dec. 28, 1954 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N00 2 940 l33 June 14 1960 Clark Co Heritage It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3 line 31 for "on" first occurrence read or column 8 lines 69 and 70 for "combined"- read combining Signed and sealed this 29th day of November .1960o (SEAL) Attest:

KARL Ho AXLINE ROBERT C. WATSUN Attesting Oficer Commissioner of Patents

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