US2827668A - Apparatus and method for manufacturing fibrous structures - Google Patents

Description

March 25, 1958 J. DA. CLARK APPARATUS AND METHOD FOR MANUFACTURING FIBROUS STRUCTURES 2 Sheets-Sheet 1 Filed July 7, 1955 INVENTOR. yam aflfih/zh B) ATTORNEYS.

APPARATUS AND METHOD FOR MANUFACTURING FIBROUS STRUCTURES Filed July 7,. 1953 March 25, 1958 J. D'A. CILARK 2 Sheets-Sheet 2 JNVENTOR. I m fiw, A BY 7 Y ATTORNEYS.

19 Gaines. (Q3. Ila-156) This invention relates to the air deposition of dry fibers in the manufacture of fibrous structures, such as continuous Webs, non-woven fabrics or layers of fibers for use in the production of laminates, papers, and the like, and it relates more particularly to an improvement in the apparatus and method described and claimed in the copending application Ser. No. 313,316, filed on October 6, 1952, now Patent No. 2,720,005.

Briefly described, the method and apparatus of the aforementioned copending application embodies the use of an elongate cylindrical housing having a fiber feed opening in the upper end through which fibers are introduced and which has a forarninous separating wall in the bottom portion through which fibers entrained in streams of air circulating about the housing are carried through the separating wall in substantially linear fiow to a foraminous collecting wall which is spaced a short distance below the separating wall. The amount of air drawn through the collecting wall for purposes of bolding the fibers separated to form a Web on the surface of the separating wall may be greater than the amount of air which passes with the fibers through the separating wall so that the deficiency can be made up by a slow infiow of air from the surrounding atmosphere into the space between the walls in amount insufficient to interfere with the smooth flow of fibers but which permits the area between the separating wall and the collecting wall for the first time to be allowed to remain open to the atmosphere without blowing fibers out into the room and to permit the use of auxiliary processing elements for treatment of the fibers as they are deposited on the collecting wall.

The entrainment of separated fibers in the air stream circulating within the housing and the subsequent passage of substantially uniformly controlled volumes of air and fibers 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 contained therein to circulate rapidly in one direction about the housing. The circulating air and entrained fibers of which there is always a large excess available, over the face of the separating wall and under positive pressure, creates conditions within the housing similar to that which exists in a shower head which provides for passage of equal volumes of air and entrained fibers through each of the openings of the separating Wall for travel to the collecting wall. The amount of air and fibers passing through the openings of the separating wall are adapted to constitute a small proportion of the air and fibers circulating within the housing thereby to maintain the shower head effect which is believed to be responsible for the uniformity in the volumes of air and fibers and in the distribution of fibers passing through the separating wall.

It has been found that in the use of a fiber depositing head of the air scrabbler type described or of the mechan- 2,827,668 Patented Mar. 25, 1953 ical scrabbler type described in the copending applicain the copending application Ser. No. 61,674, to which this invention is also applicable as an improvement, some of the fibers inevitably become entrapped and build up to form clumps on the sides of the housing and on parts not directly being swept by the air streams or mechanical blades of the scrabblers. Some of these clumps build up on portions of the housing and the openings of the separating wall While others collect on the underside of the separating wall where they can break away to form defects in the fibrous structure.

it is an object of this invention, therefore, to provide an improvement in apparatus of the type described for the deposition of dry fibers in the manufacture of fibrous structures which Will prevent the aggregation of clumps of fibers in or upon the surfaces of the depositing means and it is a related object to provide apparatus for achieving same.

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

Figure l is a sectional elevational view of a fiber depositing system embodying features of this invention;

Figure 2 is a sectional elevational view taken substantially along the line 22 of Figure 1;

Figure 3 is a sectional elevational view of a modification in a fiber depositing head embodying features of this invention, and

Figure 4 is a sectional elevational view of a still further modification of a fiber depositing head embodying features of this invention.

Referring first to the application of this invention to an air scrabbler system, in accordance with the practice of this invention, if the air is introduced tangentially at high velocity as a substantially continuous blade across the cylindrical housing, as defined in application Ser. No. 313,316, or in the event that the air is introduced tangentially into the housing from a plurality of separate inlets or nozzles, at least one or more air inlets are arranged intermittently to impinge directly but preferably indirectly upon the surfaces of the housing where fiber bundles might form, such as on the face or on the underside of the separating wall, as by the introduction of air intermittently in high velocity streams from one or more of the inlets or preferably where the effect of such intermittent introduction may be secured more readily by a reciprocating movement of one or more air streams crosswise of the housing. This intermittent or sweeping action of air streams introduced within the housing prevents the aggregation of fibers in the areas anected by the intermittently applied high velocity air streams also enhances fiber separation and distribution to the end that a more uniform concentration of fibers in air is tained and a more desirable product free of fiber bundles is produced. The main effect, however, is to sweep the separating wall rapidly with the directly or indirectl aimed jets of air which serve to prevent any appreciable building up of fiber bundles inside or outside the separating wall which might subsequently be released and fall on the web being formed. Such reaction with the intermittent streams of air seems to keep the openings of the separating wall substantially free of blocking fibers with the result that the distribution of fibers passing through the openings in the separating wall and deposited on the collecting wall remains more uniform and clumps of fibers no longer attempt to form or build up on microscopic rough spots on the upper surface of the wall and the tendency for them to form beneath the wall is also greatly reduced. In some applications it is desirable to place one or more intermittently operating or oscillating the outer surface of the separating wall .free from accumulating aggregates or hangers, as illustrated in Figures 3 and 4 of the drawings.

. As;shown in the drawings, indicates acylindrical housing-which, ina unit of medium capacity, may be dimensioned from l /2' to 2 feet in diameter and of any desired Width. An inlet openingll is provided across the upper portion of the housing in communication with a feed duct 12 into which the fibers 13' are blown or otherwise introduced. Depending uponthe type of structure that is to be produced, the fibers introduced into the duct .maybe fibers-which have previously been substantially completely separated into their individual elements or they may be inthe form of coarse fibers or aggregates or woody elements of sufiiciently low specific gravity and size as topermit flotation and entrainment in the high velocity streams of air circulated within the portion'of the housing 10. The separating wall may constitute an integral part of the housing but it is preferred to construct the separating wall as a separate plate of similarcurvilinear contour which may replaceably be secured in position to seat within the opening across the lower end portion ofthe cylindrical housing so as to adapt the fiber depositing'head for use with fibers of different character and 'of different dimensions. The openings 16 in the separating wall may be formed of spaced apertures, as described in the copending application'Ser. No. 61,674, or may constitute spaced slots extending across the separating wall and dimensioned to permit passage of fibers therethrough, as illustrated in the air scrabbler described in application Ser. No. 313,3 16. Since certain types of openings are preferable for use to the atmosphere. This avoidsthe necessity for nip rolls or other sealing means which have, heretofore been required in processes for the deposition of dry fibers entrained in air. This also'permits the use of auxiliary devices for processing the fibers during deposition onto the collecting Wall and it also permits the deposition of one layer of fibers onto another in interfelted relation to prevent delamination, without special. precautions or the like.

Even though conditions relating to a showerhead are maintained with the air or mechanical scrabbler, somefibers invariably become entrapped on'surfaces or edges within the housing or on theface or outer'surface of the separating wall. These are not always displaced but tend to build up into clots or bundles which may ulti- V mately find their way to the collecting wall to form a defeet in the fibrous structure that is formed. The improvement herein resides in the elimination of such difiiculties by a construction whereby, in' an air scrabbler system, one or more streams of high speed air are introduced tangentiallyinto the" housing or obliquely againstfthe.

can be generated by the oscillating members described" assist in causing the" desired circulation around the housing and the-crosswisemovement of the'air streams pro vides a sweeping action which tends'to equalize. thedistribution of'fibers' in the housing and providea more uniform entrainment of fibers with a corresponding more uniform deposition of fibers across the collecting wall.

. The main function of the intermittent or oscillating with one type of fibers while openings of another size or collecting wall may be a stationary member for use in the manufacture of preformsor it'may be anendless member adapted to travel continuously in one direction to collect the fibers on the surfaces thereof in the form of a continuous Web 18 having a thickness depending upon the concentration of fibers passing through the separating wall and the linear speed of travel of the collecting Wall.

Cooperating with the underside of the collecting wall 17 in the area immediately beneath that defined by the separating wall 16 is a suction box 19 in communication with a fan or other means for withdrawing air through the collecting wall to create a suction" which holds the separated fibers in position on the surface thereof. When, as is preferred, the volume of air withdrawn through the collecting wall is greater, by'a small amount, than the volume of air passing with" the fibers through the separating wall, the difference in volume will be made upby a slight'fiow 'ofair from the surroundingatmospliere into the space between the separating and collecting 'walls. When the difi'erence is properly balanced, the

inflow from the surrounding atmosphere is so slight and "gentle as to avoid interference with the linear flow. and

the distribution of fibers during passage from the separating wall to the collecting wall. At the same time, the slight inflow of air prevents fibers from blowing out into the atmosphereand thus permits the area between theseparating wall and the collecting wall to remain open streamsof'air is to scan directly or indirectly the inside surface'of the housing and the foraminous separating wall to prevent the aggregation of clumps of fibers, many of whicb,.and indeed all of those clumps formed on the outside of the plate, find their way to the structure being felted. Someof the advantages of having jets of air oscillating within the housing are that the clumping of fibers is minimized by' breaking up incipient or formed clumps byshearing action caused by the impingement ofa' localized high velocity stream of air upon the fiber clamps and which moves through and severs' them, the openings; in the separating wallremain free of blocking aggregates, and most important, the build-up of fiber aggregates is' substantially completely eliminated from the inside of the housing and" sometimes completelyfrom beneath theseparating'wall. In consequence, a more uni form web ,of separated fibers is secured, free of fiber clots and bundles and which thereby provides for an improved fibrous structure: While it is preferred to make use" of oscillatingjets'of thetype described; somewhat comparable results maybesecuredby the use of stationary jets" set at various angles and preferably set at an angle so as to impinge uponthe' separating wall indirectly and adapted for intermittent operation so as to introduce pulsing jets into thehousing to effect the desired cleansing and other results;

The intermittent or oscillating jets may be joined: with between; Therecipro'cating' nozzle 26 in this modifica tion is positioned at a level below the stationarynozzles' and cemprises 'an elongate tubing 27, having its inlet end 28 attached to a conduit 29 in communication with a source of air high pressure. The outlet end portion of the tubing extends through the wall of the housing, and is downturned at its end 30 to issue the stream of air in a tangential direction. The tubing is supported intermediate its ends in a journal 31 in the form of a bushing secured to the outer Wall of the housing. Various conventional means may be provided for effecting turning movement of the tubing to cause the nozzle end portion 30 to reciprocate or rock in a manner to cause the tangential stream of air to sweep crosswise of the housing. One such means, as illustrated, comprises a plate 32 which is fixed about an intermediate portion of the tubing 27 and is engaged at an ofiset portion by one end of a rocker arm. The other end of the rocker arm is pivotally joined to one end of a link 34 which is, in turn, pivotally mounted onto a pin 35 oifset from the center of a disc 36 adapted to be located so that reciprocating movement will be imparted to the link 34 and rocker arm 33 thereby to impart rocking movement of the nozzle 3%} in response to rotation of disc 36.

As previously pointed out, the air inlets may all be positioned at the same level or at various levels within the housing with some of the inlets directing their streams of air tangentially into the housing while the streams issuing from others are radial, some angular, and some reciprocating. It is preferred to balance the air streams so as to provide for most efiicient operation of the fiber depositing head. One arrangement wherein the inlets are located at a uniform level and spaced crosswise of the housing is illustrated in Figure 4- wherein the nozzles are stationarily fixed in various angular positions. One suitable arrangement in a housing about 2 feet wide makes use of nine inlets in fixed angular position across the housing. The first, fifth and ninth, represented by the numeral 49, are arranged to introduce the air streams tangentially within the housing. The third and seventh, represented by the numeral 41, may be positioned to direct the streams of air substantially radially into the housing so as better to disintegrate the circulating clumps of fibers by applying blasts perpendicular to their movement. The second, fourth, sixth and eighth, represented by the numeral 42, are positioned at various angles therebetween and are adapted by suitable controls to introduce their streams of air intermittently into the housing to provide intermittent jets which impart a type of displacing action to prevent the accumulation of fibers on various surfaces within and without the housing.

Instead of mounting the inlets 42 in fixed position for introducing jets of air intermittently into the housing, such inlets may be adapted for reciprocating movement 42 as previously described, continuously to introduce the air streams into the housing at various angles which sweep across the surfaces Within the housing and are preferably directed to engage the housing just prior to the face of the separating Wall to maintain the surfaces thereof substantially free of clinging or clogging fibers without afiecting the fibers deposited on the collecting wallbeneath.

The fiber agglomerates have also been found to form on the underside of the separating wall where they are able to fall with the fibers passing through the separating wall and form blemishes in the structure that is formed on the collecting wail. While this accumulation of fibers on certain points on outer surfaces of the separating wall will be reduced materially in response to the intermittent indirect action of jets upon the inner interior surfaces of the separating wall, it may be expedient to avoid such possibilities for blemishes and interference with fiber deposition substantially completely by the use of similar jets operating exterior of the housing to impinge tangentially upon the exterior side of the separating Wall preferably synchronized in its movements with jets operating intermittently or oscillating within the housing to enable increased blow with less disturbance of fiber flow.

As inthe system previously described, the jet or jets or air may issue from stationary nozzles 44 with narrow bores spaced laterally across the housing in spaced relation with the underside thereof but positioned to direct the air streams at high velocity intermittently across the surface of the separating Wall so as to sweep the surface for the removal of fibers which might cling thereto and form incipient clumps. A system of this character is illustrated in Figure 4 of the drawings.

Instead, one or more nozzles as, adapted for reciprocation as previously described, may be positioned in spaced relation with the underside of the housing for sweeping the underside of the separating wall with a high velocity stream of air as the nozzle is reciprocated. Fiber accumulation Will be minimized by reaction wiLh the air stream intermittently sweeping across the surfaces of the wall Without the need for so much air as might interfere with the flow of fibers and air in uniform volume and in the desired distribution in normal operation from the separating wall to the collecting wall.

A system based upon reciprocating nozzles Within and without the housing is shown in Figure 3 of the drawings. Reciprocation to direct the air stream laterally across the housing may be achieved by means Within the skill of the art, as illustrated by the means shown in Figure 1.

It will be apparent from the description that the reciprocal movement of some of the streams of air crosswise of the housing provides for improved operation in the development of a better distribution of fibers in the air stream and more rapid and uniform transfer of fibers from the fiber depositing head onto the collecting wall in the manufacture of fibrous structures. The intermittent action of the induced localized hi h velocity air streams upon the separating wall serves to keep it relatively free from aggregates both on the ingoing and outgoing surfaces and thus avoid the serious problem of build-ups and releases of clots of fibers which constitute a severe draw-back to the satisfactory operation of all kinds of equipment adapted to deposit fibers by way of an air stream.

By the use of nozzles having openings of small dimension, a much higher air velocity and thus a greater cleansing eifect may be had instantaneously over localized areas of the separating Wall with a given volume of free air than could otherwise be tolerated without interference or effect on the uniformity of distribution and deposition of fibers to form the web. Moreover, the crosswise movement of the jets across the surfaces of the housing serves very effectively to dislodge aggregates which might otherwise be pinned down by the blasts from fixed or non-interrupted jets.

It will be obvious that this invention may be adapted for use with other types of fiber felting heads through which fibers are transported to be laid down into a structure such as by providing suitable means to intermittently impinge jets of high velocity air across surfaces uponv which fibers may aggregate and from which such aggregates might fall or be carried to the structure to cause blemishes therein.

t will be understood that changes may be made in d tails of construction, arrangement and operation, and in the arrangement of air nozzles for the processes described without departing from the spirit of the invention, especially as defined in the following claims.

I claim:

1. In apparatus for the air deposition of dry fibers in the manufacture of a fibrous structure comprising a felting head having an inlet in one portion through which fibers are fed into the head and an outlet in another portion in the form of a foraminous separating wall through which fibers are able to pass, a collecting wall spaced a short distance from the separating wall having forarnens therein dimensioned to prevent passage of fibers, means for feeding dry fibers into the felting head, air nozzles in the felting head through which streams of air at high .manufacture of fibrous structures comprising a felting velocity are directed into-the; head; and meansfor. rocking some of. said nozzles crosswise ofthe head. whereby the: streams. of air are caused to sweep across thezhead: to -free fibers entrapped onthe surfaces thereof.

2. Apparatus for the air deposition of dry fibers in the manufacture of fibrous structuresxcompri'sing a felting head in the form of a cylindrical housinghaving an inlet, in one wall portion through. which fibe'rss are fed into thehousing, an outlet in another Wall portion in V the form of a foraminous separating wall throughwhich the foramens of the separating wall'free from aggre- 3. Apparatus for the air deposition of dry fibers in the manufacture of fibrous structure's comprising a feltinghead in the form of a housing having-an inlet in one portion through which. fibers are fed into the housing, an outlet in another portion which forms a foraminous separating Wall through which fibers 'are able to pass and a collecting. Wall spaced a short distance from the separating wall having foramens therein dimensioned .toprevent passage of fibers, means for feeding dry fibers through the inlet into the housing, a plurality of air nozzles'arranged crosswise of the housing through which streams of air at high velocity are directed into the houscome entrained in the air stream-in: uniform distribution ing, some of said nozzles being positioned todirect their 7 air streams tangentially into the housing to cause the air and fibers entrained therein to circulate rapidly about the housing, and means for causing air streams issuing from some of said nozzles intermittently to engage the surface of the housing whereby the surfaces and the fora- 'mens of theseparating wall are kept free from aggregates of fibers.

wise of the housing to free fibers entrapped on the sur faces thereof.

5. Apparatus as claimed in claim 3 in which the means for causing'air streams issuing from some of said nozzlesintermittently to engage the surfaces of said hous- 7 ing comprises means for intermittently introducing streams of air through some of said nozzles within the housing. a

6 Apparatus as claimed in claim a in which said streams of air intermittently engaging the surfaces ofthe housing comprise fine streams of air'of higher velocity than issue from the remainder of the air nozzles so as not-3m interfere with the circulating movements of the air and fibers about the housing and'their'passage through thes'eparating wall to the collecting wall.

7. Apparatus for the 'depositionof dry fibers in the 8 7 head: including a. cylindricali housing: having an inlet: in one portion throughrwhich fibersarefedintothe housing, an outlet' in. another portion which: forms aforarn-q inousl separating; wallthr'ough. whichfibersl are abletov pass, and includes: a. collectingwall. spaced ashort; distance from theseparating'wallhaving foramens therein dimensionedfto prevent passage.-of.fibers;.means for. feeding: dry fibers; through theinlet intov the housing,- a plurality of inlets through which streams of. air atv high velocity aredirected into the housing,v some. of the air inlets. being positioned to direct their-streamsof air tangentially intorthe. housing; others-of said air inlets'being;

positioned to direct their streams radially intothe housing, while still others are positionedito direct their streams at'angles between radial and tangential, and means for rocking someof said air'inle'ts'. crosswiseof the housing other than those which are positioned. to direct their streams of: air radially into the housing to. C3l1$ ilil6 streams. of air issuing therefromtosweep across thesur faces of" the; housing. whereby the surfaces and the foramens of the separating wall are kept fre'e'from aggregatesof fibers; whereby the fiberswithin. the housingbeand in' substantial separation for. passage with the air through the. separating wall to. the collecting wall.

8. Apparatus as claimed in claim 3 which includes air" inlets positioned exteriorly of the housing and; at an angle. todirect the streams of air issuing therefrom onto the separatingwa'll, andimeans for causing theair streams issuing therefrom intermittently to 'engagefportionsl ofthe separating'wa'll to freenthe surfaces from agglomerates of. fiberswhich might collect thereon.

9. In themanufacture of fibrous structures by: the deposition of fibrous elements entrained in an air stream wherein. the air' stream and entrained'fibers are passed through a felting head having a foraminouswall through V which air and entrained fibers are able to pass, the im-' provement which comprises intermittently sweeping 'theinterior of the felting head with a jet of high velocity'air directed intothe stream ofair entrained fibers circulating about thezfelting head to' prevent the aggregation of fibers onto. the surfaces thereof, and sweeping the exterior ofthe' foraminous wall through which the fibers pass with a fine jet of high velocity air directed substantially toward said wall.

. 10. In the deposition of dry fibersentrained in an-air i stream wherein the air stream and entrained fibers are passed through a felting head through openings toa collectingmember in the formation of a fibrous structure,

the method of subjecting at least some of the surfaces of the head 'to the effect of the intermittent application of jets of. high velocity air separate and apart fron'rthe' air stream entraining the-fibers for preventing the aggregation'of fibers on the interiorsurface of the felting head acted upon by the jets and the openings-leading to the collecting member;

References Cited in the file of thispaten t UNITED STATES PATENTS Clark et a1. o r. 11, 1955

Claims (1)

10. IN THE DEPOSITION OF DRY FIBERS ENTRAINED IN AN AIR STREAM WHEREIN THE AIR STREAM AND ENTRAINED FIBERS ARE PASSED THROUGH A FELTING HEAD THROUGH OPENINGS TO A COLLECTING MEMBER IN THE FORMATION OF A FIBROUS STRUCTURE, THE METHOD OF SUBJECTING AT LEAST SOME OF THE SURFACES OF THE HEAD TO THE EFFECT OF THE INTERMITTENT APPLICATION OF JETS OF HIGH VELOCITY AIR SEPARATE AND APART FROM THE AIR STREAM ENTRAINING THE FIBERS FOR PREVENTING THE AGGREGATION OF FIBERS ON THE INTERIOR SURFACE OF THE FELTING HEAD ACTED UPOM BY THE JETS AND THE OPENINGS LEADING TO THE COLLECTING MEMBER.

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