US2714749A

US2714749A - Apparatus for deposition of dry fibers int the manufacture of fibrous structures

Info

Publication number: US2714749A
Application number: US371258A
Authority: US
Inventors: James D A Clark; Bror E Anderson
Original assignee: AB Dick Co
Current assignee: AB Dick Co
Priority date: 1953-07-30
Filing date: 1953-07-30
Publication date: 1955-08-09
Anticipated expiration: 1972-08-09

Description

X Aug. 9, 1955 J. DA. CLARK ET AL APPARATUS FOR DEPOSITION OF DRY FIBERS IN THE MANUFACTURE OF FIBROUS STRUCTURES 2 Filed July so, 1955 IN VEN TOR. %m dmfim W 3y I 3 1% 1M,

ATTORNEYS.

United States Patent O APPARATUS FOR DEPOSITION OF DRY FIBERS IN THE MANUFACTURE OF FIBROUS STRUC- TURES James DA. Clark, Longview, Wash., and Bror E. Anderson, Park Ridge, 111., assignors to A. B. Dick Company, Niles, 111., a corporation of Illinois Application July 30, 1953, Serial No. 371,258

3 Claims. (Cl. 19-156) This invention relates to the air deposition of dry fibers in the manufacture of fibrous structures such as continuous, nonwoven webs and fabrics formed of fibrous elements, such as separated fibers or wafers, and it relates more particularly to an improvement in the apparatus for the manufacture of fibrous structures which is described in my copending application Ser. No. 313,316, filed on October 6, 1952.

Briefly described, the method and apparatus of the aforementioned copending application embodies the use of an elongate cylindrical housing having one or more inlet openings in the upper end through which fibers are introduced and which has a foraminous separating Wall in a spaced portion thereof through which fibers entrained in a stream of air are carried through the separating wall for substantially linear flow to a collecting wall spaced a short distance below the foraminous separating wall and upon which the fibers are deposited in an interfelted relation. The collecting wall may be foraminous to enable air to be withdrawn from the underside for holding the deposited fibers onto the surface thereof and the amount of air withdrawn through the collecting wall is preferably adapted to be greater than the amount passing through the foramens of the separating wall so that air will flow slowly from the surrounding atmosphere into the space between the separating wall and the collecting wall but in amounts incapable of interfering with the linear flow of fibers. By the balancing of the air flow as described, an apparatus may be supplied which for the first time permits the area between the separating wall and the collecting wall to remain open to the atmosphere without blowing fibers out into the room.

The entrainment of fibers in the air stream within the housing and the subsequent passage of substantially uniformly controlled volumes of air and fibers from the r housing through the openings of the separating Wall to the collecting Wall is achieved by an air scrabbler in which streams of air at high velocity are introduced tangentially into the housing to cause the air and the fibers therein to circulate rapidly in one direction about the housing. This causes the fibers within the housing to become entrained within the air stream. The circulating air and entrained fibers, of which there is always an excess available, over the face of the separating wall and under positive pressure, not only keeps the openings in the wall substantially free of clogging fibers but because of the pressure, resulting from the excess of both air and fibers, generates a shower head eifect which results in the passage of equal volumes of both air and entrained fibers through each of the openings of the separating wall to the collecting wall. The volume of air and fibers passing through the separating wall in response to the shower head effect constitutes a relatively small proportion of air and fibers circulating within the housing.

It is an object of this invention to provide improvements in the method and apparatus for the air deposition of dry fibers in the manufacture of fibrous struc tures and it is a related object to provide a method and apparatus for the air deposition of dry fibers using a fiber depositing head based upon an air scrabbler in which means are provided for reducing fiber agglomeration and maintaining fiber separation and distribution for the passage of uniform volumes of fiber through the foramens of the separating wall and the formulation of a fibrous structure having a uniform distribution of fibers on the collecting wall; and in which a minimum number of fiber bundles are formed to interfere with the smooth and uniform transfer of fibers from Within the housing to the collecting wall or deposit undesirable bundles of fibers in the web which is formed on the collecting wall.

These and other objects and advantages of the invention will hereinafter appear and for purposes of illustration, but not of limitation, embodiments of the invention are shown in the accompanying drawing in which:

Figure 1 is a schematic view in sectional elevation showing a fiber depositing head embodying features of this invention;

Figure 2 is a sectional view taken substantially along the line 2-2 of Figure 1.

It has been found that a uniform distribution of fibers in the air stream within the housing may be secured and agglomeration of fibers into bundles may be lessened when some of the air streams are introduced into the housing at angles varying from tangential, as before, to radial with at least some of the jets introducing streams of air in a substantially radial direction into the housing while most of the jets continue to be introduced substantially tangentially.

The fiber depositing head in which the concept of this invention has primary application comprises a cylindrical housing 10 which may be of variable width depending upon the width of the fabric to be formed. In a unit of medium capacity, the housing 10 may be 1 /2 feet in diameter and 4 feet in width. A feed opening 11 extends practically completely across the upper portion of the housing in communication with a feed duct 12 through which fibrous elements 13 in the form of sparated fibers of wood, cellulose, synthetic fibers, mineral fibers or pulp fibers, or fibrous elements of substantial dimension, such as thin wafers or cut strands, may be fed, preferably at a continuous and constant rate into the housing.

A foraminous separating wall 14 is provided in the lower portion of the housing through which fibrous elements entrained in air pass on their way towards a collecting wall 15 upon which the fibers are separated in interfelted relation to form a web 16 on the surface thereof. The foraminous separating wall may constitute a separable foraminous member secured in position across an opening 17 Within the housing in a manner to permit exchange so that the type of openings or an arrangement of openings 18 best suited for particular fibers may be used for most efiicient production. The openings in the separating Wall may comprise a plurality of spaced apart apertures controlled as to size and spacing for particular fibrous elements as described in the copending application Ser. No. 61,674, or the openings maye be in the form of one or more continuous slots extending across the housing in circumferentially spaced apart relation, as described in the copending application Ser. No. 313,316.

The collecting wall 15 is preferably formed of an end-. less screen adapted to be advanced in one direction con tinuously across the area beneath the foraminous separating Wall 14 or it may be in the form of a series of caul';

plates upon which the fibrous elements are deposited to pro'ducesaniinterfelte'd :structure for molding into panels while on. the, owl, plates. .The .foraminous ..collecting vwall which is preferred in the manufacture of webs of separated fibers, as shown, is supported upon a rigid surface 19 havingzlanr opening izflrinzthe areal lyingnbeneath: the separratzingrwlall. :AssuctionrboxflL isaprovide'd :in;cornmunica- ..-tiona :withrth opening; andsservesizforznse inuwith'drawing' .a ItMOlUIIICHOfJZZlI'ifIQm the: underside rof the .icollectionwwall which. atilleastiequalztto andepreferably: larger than .the Molume: f air-,which-upasses'with the'fibersthroughthe :separatingmvall with the resultthat .the. deficiency is made supbbyza ssl-ight .in'flow :of .-'.air .into :the space. between the aseparatingtwall and-the collectingv walli from the. surroundjngzatmosphere. when thiscdifference in air volumesis :small; the::inflow:of= -airwis;of such;character .as not to-inter- :tfere vwith: therz'substantially' linearsmovement of the fibers fromi theaseparating .rwall toithelcollecting wall withthe resultrthatithe fiber;depositing areamanlbe allowed to'remain open to the atmosphere without disturbingthe distributionszofcfiberssand without loss of'fibers into the atmosphere.

iuMarkedtimprovementshave:been foundto result with respect ate 3 the .distribution and separation. of the fibers within the housing when, instead of introducing all of the rairsstreamsitangentially into the housing, some oftheair streams are introduced radially While others are introduced at angles therebetween, although such inbetween jetsare snotmecessary. IIt is.-best rwhenzthegreatestnumber of inlets are positioned to introduceathe streamstangentially whilmfewerrare spaced across'the housing and positioned torintroduee the;streamsaradially, :while possibly still a few others arepositionedztointro duce' the air streams at angles therebetween.

:Oner satisfactory "arrangement is illustrated in the drawings' where eleven inletszareillustrated as extending across therhousing. zTheifirst, third, fifth, seventh, ninth and eleventhirilets: indicated by the letter -T .are positioned to introduce the streams .sof i'high velocity -air tangentially into: theihousiug. 'xThe'fourth and eighth, indicated by the letter Reareapositionedito introduce the streams of-air radially. into .the:housing,. and. thC'-S6CO1'ld,SiXth and tenth inlets,.indicated by the letter A, arepositionedto introdUCfiJIhfilIFStI'CfiIIIS of. air at:an..angle between radial and tangential.

:In:. theory,:it..is believed that. the tangential streams'of airsintroduced: into "the: housing: impart the forces forcircula'ting: movement of the air and fibers'about the housing to;providei.the= layer-which moves constantly under positive pressure.:across:the foramens'of the separating wall and from which a-smallspropor'tion entrained in air'peels off fortpassagewith the. air through thejforamens .of' theseparating wall to the collecting wall. While the radial streams ofn-airlintroduced into 'the housing would seem to interfere with .this'circulatingmovement,-they, in fact, do not impart such.interferencertand instead appear to improve the entrainment-and the distribution of the fibers -in the circulating streams of. air with theresult that fiber clumping iszmarkedlyareduced as compared'to that which exists in therabsence ofsuch:radial'streams. Because ofthe greater degreerofsseparat ion and reduced clumping, the productioniiof:a'moreiuniform -layer ofseparated fibers is secured withrless interference and interruptions to keep the foramensof the separating' wall clear for passage of uniform volumes of airand fibers therethrough.

:Thesainstreams:introducedatangles between radial and tangentialrarernotsalways necessary but they assist both in::circulating the air and fibers about the housing over the separatinggyalland maintaining more complete fiber separationrandz'distribution. The moreimportant function of the inbetweeninlets -.is:to-impinge upon the face of the separating wall and thereby assist-in the removalofany fiberstwhichvmight become entrapped and upon which agglomenates might form to interfere with the fiber depositingzproeess:or'toprovide clumps-which drop onto the fabrictandconstitutean impurity therein.

Various meansfor the adjustment of the angular relation ,of the .air..inlets.may .beprovided. As .illustratedwin Figure 1, one such means includes an arm 21 which engages the nozzle 22 outwardly of the housing and is pivoted at one end, as at 23, upon rocker arm 24 which is adapted to be secured in a vertical angle of adjustment by the screw and nut means 25 illustrated.

'Further-toiassist injthe smoothness ofoperationof the fibendepositinghead and the introduction offibers therein, a bafile plate 30 is provided of curvilinear construction which issecured .to the inner wall.of the housinginadvance. of the inlet opening to-provide'a'curvilinear wall therein which terminates ata levelbelow the inletopening so as to deflect the circulating air streamheyond the inlet opening 'during=circulating"movements. The effect of such deflection of the. air-stream'by the baffle 30 causes a negative pressure to exist at the inlet opening with the result that the fibers fed into the opening through the feed chute are positively drawn into the-housingand turbulence which ordinarily might exist in the feed openingis thus substantially. completely-eliminated.

i It will bexunderstood that furtherchanges may be made in' the. details of construction, arrangement and operation without departing from the :spirit of the invention, -'-espe- .ciallyasdefinedin the following claims.

We claim:

1.. Apparatus for the air: deposition of dry fibers in'the manufacture. of :fibrous structures comprising '-a substan- .tially "cylindrical housing having an' inlet -'-in 1 one *portion throughzwhich fibers-are fed: into "the-housing; arr-outlet in anotherportion v which :forms -a foraminous separating .wall through iwhich fibers -are=able 'to pass, a collecting wall spaced at short-distance from theseparating-wall having'foramens therein dimensioned to prevent passage of fibers, .means for feeding-dry' fibers through-the inlet into the housing and azplurality= of air:n0z'zles in the housing through which streams of air at high velocity are-directed into therhousing,'zsome'of said nozzles being posit-ionedto directnstreamssof airtangentially into the housing,others of saidznozzlesi'being positioned to direct theirstrearns of air radially into the'housingwhereby the'airrand contained fibers rare caused towc'irculate rapidly about the housing in one directionsasaa composite stream having a substantially uniform. distribution of the "fibers-entrained therein for passage with the air: through the separating wall to i the collecting wall.

'2. 'Apparatus for the-air deposition of'dryfibers in the manufacture of fibrous=structures comprising a substantially cylindricalihousing'havinga fiber i-r'rlet-in one portion: through which; fibers are fed-into the'housing, an outlet in another portion Which-forms -a-foraminous separating wall 'throughwhichfibers are able to=pass,-'acollectingwall spaced a :short distance from theseparating wall having foramens therein dimensioned to prevent passage ,offibers, means forfeeding dryifibers through the-.inletiinto the housingpan'da plurality of'air inlets'in the housing through which-streams of air at high velo'city are directed into =the' 'housing, .some of said air'in-lets being positioned to directtheir streams of'air tangentially into the housing,others ofsaidair=inlets being positionedto directtheir:streams ofair radially into the housing,uwhile still others are positioned to direct their streams of air into the housing+at angles between'tangential and radial whereby: the: air and entrained fibers are caused -.to circulate as a.composite-'stream rapidly about the housing-.and:entrain theifiberstherein in uniform distribution and maintain separation so .that aesmall portion of the air i and ,fibers contained :within the iuhousing =will pass together through the separating wall tothe collecting wall.

'3. Apparatus :for the air deposition of-dry fibers in the, manufacture of fibrous structures :zcornprising a 'substantiallyzcylindrical housing. having: aniinlet in oneaportion through which fibers are fed into the housinggan autlet sin anothenportion which "forms a 'foraminous separating wall through which fibers are able to pass, a collecting wall spaced a short distance from the separating Wall having foramens therein dimensioned to prevent passage of fibers, means for feeding dry fibers through the inlet into the housing at a rate to maintain a load of fibers within the housing, a plurality of air nozzles arranged transversely across the housing through which streams of air at high velocity are directed into the housing, most of said air nozzles being positioned to direct their streams of air tangentially into the housing, others of said nozzles being positioned to direct their streams of air radially into the housing, while still others are positioned to direct their streams of air into the housing at an angle between tangential and radial whereby the air and entrained fibers are caused to circulate rapidly as a composite stream about the housing in one direction and the fibers within the housing entrained in the air stream in uniform distribution and in a manner to maintain substantial sepaartion for passage with the air through the separating wall to the collecting wall.

References Cited in the file of this patent UNITED STATES PATENTS 2,317,895 Drill Apr. 27, 1943 2,589,008 Lannan Mar. 11, 1952 2,641,028 Steele June 9, 1953 2,651,812 Black Sept. 15, 1953

Claims

1. APPARATUS FOR THE AIR DEPOSITION OF DRY FIBERS IN THE MANUFACTURE OF FIBROUS STRUCTURE COMPRISING A SUBSTANTIALLY CYLINDRICAL HOUSING HAVING AN INLET IN ONE PORTION THROUGH WHICH FIBERS ARE FED INTO THE HOUSING, AN OUTLET IN ANOTHER PORTION WHICH FORMS A FORAMINOUS SEPERATING WALL THROUGH WHICH FIBERS ARE ABLE TO PASS, A COLLECTING WALL SPACED A SHORT DISTANCE FROM THE SEPARATING WALL HAVING FORAMENS THEREIN DIMENSIONED TO PREVENT PASSAGE OF FIBERS, MEANS FOR FEEDING DRY FIBERS THROUGH THE INLET INTO THE HOUSING AND A PLURALITY OF AIR NOZZLES IN THE HOUSING THROUGH WHICH STREAMS OF AIR AT HIGH VELOCITY ARE DIRECTED INTO THE HOUSING, SOME OF SAID NOZZLES BEING POSITIONED TO DIRECT STREAMS OF AIR TANGENTIALLY INTO THE HOUSING, OTHERS OF SAID NOZZLES BEING POSITIONED TO DIRECT THEIR STREAMS OF AIR RADIALLY INTO THE HOUSING WHEREBY THE AIR AND CONTAINED FIBERS ARE CAUSED TO CIRCULATE RAPIDLY ABOUT THE HOUSING IN ONE DIRECTION AS A COMPOSITE STRAM HAVING A SUBSTANTIALLY UNIFORM DISTRIBUTION OF THE FIBERS ENTRAINED THEREIN FOR PASSAGE WITH THE AIR THROUGH THE SEPERATING WALL TO THE COLLECTING WALL.