US3740797A

US3740797A - Method of forming webs and apparatus therefor

Info

Publication number: US3740797A
Application number: US00108545A
Authority: US
Inventors: A Farrington
Original assignee: Johnson and Johnson
Current assignee: Johnson and Johnson
Priority date: 1971-01-21
Filing date: 1971-01-21
Publication date: 1973-06-26
Anticipated expiration: 1990-06-26
Also published as: AR199763A1; NL174377B; NL7200917A; US3772739A; FR2122595A1; JPS556747B1; FI51961C; FI51961B; AU3817072A; FR2122595B1; BR7200366D0; NL174377C; DE2202986A1; SE373169B; GB1375584A; IT948267B

Abstract

A process and apparatus for forming an air-laid, nonwoven web from separate supplies of individualized fibers, such as textile and papermaking fibers. Supplies of fibers are fed to oppositely rotating lickerins that are rotated at speeds which are optimum for the fibers being individualized by the lickerins. The individualized fibers are doffed from the lickerins by centrifugal force and high velocity air streams directed against the fibers clinging to the lickerin clothing. The fibers from each supply are entrained in their respective air streams, which are impelled at high rates of speed toward each other, and the air streams come together in a mixing zone. The doffed fibers are given an initial trajectory as they leave their respective lickerins, and the inertia of the fibers in the air streams is sufficient to bring the fibers to the mixing zone and effect blending of at least a portion of the fibers from each supply in the mixing zone. In communication with the mixing zone is a suction actuated condensing means where the fibers are deposited to produce a nonwoven web of fibers, for example, an isotropic nonwoven web. The process and apparatus can be varied to form a variety of nonwoven webs, using as the fibers of these webs two different fibers of the same, or of different lengths. A variable that can be introduced to vary the web construction includes a baffle that can be interposed between the two separate air streams to control the location where the two air streams are intermixed.

Description

United States Patent [191 Farrington June 26, 1973 METHOD OF FORMING WEBS AND APPARATUS THEREFOR Allan P. Farrington, Englishtown, N.J.

[73] Assignee: Johnson & Johnson, New Brunswick,

[22] Filed: Jan. 21, 1971 ['21] Appl. No.: 108,545

[75] Inventor:

Primary Examiner-Dorsey Newton Attorney-Michael Q. Tatlow, Harold L. Warner and Robert L. Minier I [57 ABSTRACT A process andapparatus for forming an air-laid, nonwoven web from separate supplies of individualized fibers, such as textile and papermaking fibers. Supplies of fibers are fed to oppositely rotating lickerins that are rotated at speeds which are optimum for the fibers being individualized by the lickerins. The individualized fibers are doffed from the lickerins by centrifugal force and high velocity air streams directed against the fibersclinging to the lickerin clothing. The fibers from each supply are entrained in their respective air streams, which are impelled at high rates of speed toward each other, and the air streams come together in a mixing zone. The doffed fibers are given an initial trajectory as they leave their respective lickerins, and the inertia of the fibers in the air streams is sufficient to bring the fibers to the mixing zone and effect blending of at least a portion of the fibers from each supply in the mixing zone. In communication with the mixing zone is a suction actuated condensing means where the fibers are deposited to produce a nonwoven web of fibers, for example, an isotropic nonwoven web.

The process and apparatus can be varied to form a variety of nonwoven webs, using as the fibers of these webs two different fibers of the same, or of different lengths. A variable that can be introduced to vary the web construction includes a baffle that can be interposed between the two separate air streams to control the location where the two air streams are intermixed.

17 Claims, 11 Drawing Figures June 26, 1973 Unfitefi States Patent Farrington METHOD OF FORMING WEBS AND APPARATUS THEREFOR This invention relates to an improved apparatus and process for air-laying fibers to produce nonwoven webs consisting of a more or less uniform intermixture of randomly oriented fibers. It is particularly directed to producing a substantially homogeneous blend of long and short fibers, i.e., textile length and paper-making fibers.

Fibers are usually classified according to length, with relatively long or textile length fibers being longer than about one-fourth inch and generally between 7% and 2% inches in length. The term long fibers, as used herein, refers to textile fibers having a length greater than one-fourth inch, and the fibers may be of natural or synthetic origin. The term short fibers, as used herein, refers to papermaking fibers, such as wood pulp fibers or cotton linters having a length less than about one-fourth inch. While it is recognized that short fibers are usually substantially less costly than long fibers, it is also recognized that for some uses it is desirable to strengthen a nonwoven web of short fibers by including a blend of long fibers therein.

Nonwoven fabrics are structures consisting of a random assemblage or web of fibers which are bonded together with an adhesive to provide the desired strength. Nonwoven fabrics have gained considerable prominence within the last two decades because of their low cost to manufacture, as compared to the cost of making more conventional textile fabrics by weaving or knitting. This has come about since nonwoven fabrics can be made with physical properties and appearance more or less comparable with the more expensive woven fabrics. Nonwoven materials have been used for hand towels, table napkins, curtains, hospital caps, draperies, etc. They are usually available in a wide range of fabric weights of from as little as about 100 grains per square yard to as much as about 4,000 grains, or more, per square yard.

Nonwoven fabrics may be made up of webs in which the fibers are either more, or less oriented, or randomly disposed. Webs in which the fibers are oriented generally have the major proportion of their fibers aligned in one direction, i.e., in the machine, or long direction, with the result that these webs are anisotropic. Such webs are relatively strong in the machine direction. On the other hand, isotropic webs are made up of randomly disposed fibers which extend in all directions andthus have substantially uniform strength in all directions.

There have been many different processes and apparatuses for producing nonwoven webs. One of the well known ways for producing nonwoven webs of textile length fibers is by employing a conventional carding process which results in an anisotropic web, since the fibers are aligned predominantly in the machine direction. Another method that could be used is a garnetting process, in which the fibers have less orientation than carded webs. These webs are generally of unsatisfactory uniformity and are also limited to textile length fibers. The ways in which webs can be produced by either of these techniques is limited, and these techniques do not lend themselves for use in making very low cost nonwoven fabrics,'especially embodying the use of relatively inexpensive wood pulp fibers.

Another current way for producing a random web of textile length fibers is the Rando-Webber" process, wherein pre-opened textile length fiber material is delivered as a loose mat to a web-forming unit. The web is brought into contact with a lickerin that further opens the fibers and introduces them into a high velocity, low pressure air stream. The fibers are subsequently deposited in random fashion on a condensing screen to produce a substantially isotropic web. While this process is generally satisfactory to provide a relatively uniform random web of textile length fibers, it is generally not suitable for use with short fibers, nor with blends of short and long fibers. Also, this machine has limited throughput capacity.

As described in Langdon U.S. Pat. No. 3,512,218, granted May 19, i970, air-laid, isotropic, nonwoven webs may be formed by placing two lickerin and rotary feed condenser assemblies in parallel. In the process of this patent, individual fibers deposit as a mat on the condenser and are then fed to the lickerins, where the fibers are individualized. These parallel systems use a single air stream that is split into two parts to doff the fibers from the lickerins and deposit them as streams of fibers onto a suction box where the final web is formed. The same fibers are processed in each assembly and there is no blending of the fibers in advance of the suction box. While the apparatus of this patent doubles the fiow rate that can be obtained with a similar single system, it has deficiencies in that it cannot be employed to homogeneously blend two streams of fibers.

Wood U.S. Pat. No. 3,535,187, granted Oct. 20, 1970, discloses an apparatus for producing a nonwoven web comprised of two or more separate layers of different randomly oriented fibers apparently joined at the interface of adjacent layers by a relatively small mixture of the fibers. The webs produced by this apparatus are comprised essentially of textile length fibers, although the patent contemplates that continuous filaments and wood pulp fibers can also be included. In the webs produced by the process of this patent, textile length fibers extending generally perpendicularly between the opposed faces of the web serve to knit or tie the fiber layers together.

The apparatus of the Wood patent, as in the apparatus of Langdon U.S. Pat. No. 3,512,218, includes two lickerin and rotary feed condenser assemblies. Individualized fibers from each lickerin are deposited as layers on separate cylindrical condenser screens, each related to a lickerin. The two condenser screens are positioned closely adjacent one another and the layers of fibers on the condensers are compressed between the condensers to form a composite nonwoven web having some blending of the fibers at the interface between the layers.

In the process of the Wood patent, the fibers are doffed from their respective lickerins by high-speed turbulent air streams that move faster than the peripheral speeds of the lickerins. The fibers are entrained in the air streams moving past the lickerins. The velocities of these air streams are controlled so that when they are in the vicinity of the condensers, the velocities are reduced to where the entrained fibers will not be forcibly impacted on the condensers. A balance must be achieved in the air flows in each of the condensing chambers so that the individual fibers have only just enough kinetic energy to deposit themselves in isotropic web formation. Due to the low velocity of the air streams carrying entrained fibers from the lickerins to the condensers, there is a minimum of blending of the fibers in their passage in the regions adjacent the condensers, and hence the resulting composite nonwoven web has only a minimal region of intermixed fibers.

The method and apparatus of the present invention can be used to form nonwoven webs that are a blend of randomly oriented long and short fibers. This is in sharp contrast to the prior art processes and apparatuses that were capable of forming nonwoven webs made up of only all short fibers or all long fibers, or a composite web made up of layers of both long and short fibers.

In general, the desired characteristics of the nonwoven end product, as well as its utility dictate the type of fibers and the relative proportions of long and short fibers to be used. Thus, for example, the product may require one or more characteristics, such as tear resistance, abrasion resistance, washability, and stretchability, burst strength, absorption or nonabsorption to dif-' ferent liquids, heat scalability, ability to resist delamination, etc., all of which will influence the type of fiber or mixture of fibers to be used. Thus, by way of specific example, absorbent products requiring strength'characteristics may be a combination of two or more different fibers, such as wood pulp fibers and rayon, or similar fibers in varying percentages.

Likewise, again depending on the nature of the fabric desired, the mixed fibers in the fabric may possess substantially random characteristics as opposed to oriented fiber characteristics in order to provide for balanced properties in both the machine and cross direction of the fabric. For example, in the case of products intended for surgical, or similar, uses requiring absorbency characteristics, such as covering layers for sanitary napkins, absorbent layers for surgical drapes, etc., mixtures of randomly oriented short and long fibers are required to provide improved mechanical characteristics; while in the case of nonwoven materials suitable for use as disposable items in the field of diapers, short fibers are generally employed.

Typical of the short fibers in the mixtures of fibers obtained by the process of the present invention are wood pulp fibers from various types of woods, cotton linters, asbestos fibers, glass fibers, and the like; with wood pulp fibers being those which find most frequent use in a large variety of products due to their ready availability and economical attributes. Wood pulp fibers are commercially available in the form of pulpboards, which come in varying thicknesses and lengths.

Typical of the long or staple length fibers are synthetic fibers, such as cellulose acetate fibers, vinyl chloride-vinyl acetate fibers, viscose staple rayon, and natural fibers, such as cotton wood or silk.

In the case of staple orlong length fibers, such as rayon, forexample, they, are normally commercially available in bale form in various fiber lengths. In the present invention, the staple fibers are generally introduced in a pre-opened oriented condition, such as in the form ofa carded web or carded batt, but these fibers may be presented to the machine by other means, such as a chute. If desired, in place of using a carded batt of only rayon, a mixture of rayon and other fiber, or fibers, or for that matter, a mixture of any two, or more different lon'g fibers can be employed.

Combinations of any of the short and staple or long fibers may be employed in this invention. The denier of the fibers used may vary over a wide range and may be from one-half to 100, depending on the type of fiber employed and the requirements of the nonwoven material. Commonly, when using staple fibers; such as rayon, the denier will vary from 0.75 to 5 or 6 denier.

Those skilled in the art have long recognized the need for a process and apparatus that can economically produce a non-woven web of a mixture of long and short fibers, especially one wherein the mixture of long and short fibers is randomly oriented more or less uniformly throughout the web, so that the web has substantially uniform strength characteristics lengthwise and crosswise thereof. Of particular interest has been the desire to obtain an air-laid nonwoven web of homogeneously blended, randomly oriented short and long fibers which combines the cheapness of short fibers with the strength of long fibers together with substantially uniform strength characteristics throughout the long and short dimensions of the web. There has also been the need for a single apparatus that is flexible enough to produce air-laid nonwoven webs of a mixture of long and short randomly oriented fibers in which the webs have a variety of fiber distribution patterns, including, (1) webs that have outer layers made up each of two different fibers and an intermediate layer that is a homogeneous blend of the two fibers, (2) webs that have a predominance of one fiber at one face of the web and a predominance of a second fiber at the other face of the web and a mixture of the two fibers in a transition zone between the faces, wherein the fiber which predominates at one face diminishes progressively from that face towards the other face, and vice versa, and (3) a web made of two separate layers of different fibers that are interlaced only at the region of their interface.

There have been a number of attempts to produce non-woven webs made of a homogeneous mixture of randomly oriented short and long fibers, but these webs, while generally satisfactory for some uses, are not of sufficiently high quality to permit them to be used without an outer facing layer. The reason for this is that in the apparatus used, clumps or hardened particles of broken or compacted fibers commonly referred to as salt, were formed and remained distributed throughout the web. With these clumps and salt, the webs were not suitable for making products, such as surgical towels, dressings, disposable diapers, sanitary napkins, cloths, cosmetic pads, and the like, although in some instances they could be used in conjunction with a high quality facing layer.

One apparatus used to make a nonwoven web of a homogeneous mixture of randomly oriented long and short fibers includes the use of a milling device, such as.

a hammer mill, to individualize the short fibers and a lickerin to individualize the long fibers. The individualized short fibers are entrained in an air stream leading to a mixing zone into which the long fibers are introduced, where the fibers are intermixed. The mixture of fibers is deposited on a condenser to form a web of a random mixture of long and short fibers. In these webs, the intermixed fibers are not homogeneously blended; in fact, in such webs, there is more or less of a stratification of the fibers in layers, with the long fibers predominating on one side of the web and the short fibers predominating on the other side. A particular disadvantage of this apparatus was that the hammer mill did not completely individualize the wood pulp fibers and, in

consequence; clumps of fibers and/or salt resulted.

Another method used to blend a mixture of long and short fibers into a nonwoven web of randomly oriented fibers involves the step of introducing a mixture of preopened long and short fibers to a single lickerin where the mixture of long and short fibers is individualized. The individual fibers, but still in admixture, are introduced into an air stream and conveyed to a condenser where they were formed into a web. This method has a significant disadvantage in that in order to prevent degradation of the long fibers, it is necessary to operate the lickerin at the optimum speed for the long fibers, which is much below that which is optimum for short fibers. This necessary compromise seriously limited the rate at which the fibers could be processed through this system and this economic disadvantage militates against its use.

A recent development in this field of air-laying webs has overcome a number of the aforementioned problems in the apparatus previously used and makes possible production of a non-woven web of a homogeneous mixture of long and short fibers, free from consequential amounts of clumps and salt. The apparatus and method of this development are described and claimed in a commonly owned application Ser. No. 108,547 filed in the name of Ernest Lovgren on even date herewith.

In the Lovgren apparatus and process, long and short fibers to be blended are individualized separately and simultaneously byseparate high speed lickerins, one for each type of fiber, that are operated at speeds optimum for the specific fibers acted upon. For example, in the case of pulpboard, the lickerin is operated in the order of 6,000 rpm. to individualize the wood pulp fibers, and the long fibers, the staple length fibers, for example, rayon, are individualized by the lickerin acting on these fibers, operated at a speed in the order of 2,400 rpm. At a speed of 6,000 rpm., rayon fibers are damaged.

In the Lovgren'apparatus, individualized fibers are doffed from their respective lickerins by separate air streams. The fibers are entrained in the separate air streams and the air streams are subsequently intermixed in a mixing zone to homogeneously blend the fibers entrained therein. The homogeneous blend of fibers is then deposited in random fashion on a condenser disposed in proximity to the mixing zone. The air streams generated by the high speed operation of the lickerins and by a suction fan located in the condenser, which acts to draw air past the lickerins, convey the fibers to the condenser.

While the Lovgren apparatus represents a substantial advance in the art, the apparatus has limitations in that it does not lend itself for use in making a wide variety of webs. I

In accordance with the present invention, there is provided a novel method and apparatus that can be practiced to produce a wide variety of nonwoven, airlaid isotropic webs made up of a substantially uniform mixture of long and short fibers, or of two different kinds of long or short fibers. Included in these webs are webs which cannot be made in the Lovgren apparatus, such as, for example, (1) webs that have outer layers made up of each of two different fibers and an intermediate layer that is a homogeneous blend of the two fibers, (2) webs that have a predominance of one fiber at one face of the web and a predominance ofa second fiber at the other face of the web and a mixture of the two fibers in a transition zone between the faces, wherein the fiber which predominates at one face diminishes progressively from that face towards the other face, and vice versa, and (3) a web made of two separate layers of different fibers that are interlaced only at the region of their interface.

An embodiment of the present invention illustrates an apparatus in which two sources of fibers, such as pulp and rayon, are individualized by separate lickerins and formed into a web. Each of the sources of fibers is guided by a nose bar into engagement with its respective lickerin, each being rotated at a high speed suitable for the fibers it is to act on, to individualize the fibers directed thereto. The lickerins are disposed parallel to each other and are rotated in opposite directions, i.e., toward each other. When the web is to be made up of long and short fibers, the lickerin for the short fibers is rotated at the maximum speed it can be operated without damaging the short fibers. The lickerin used for individualizing the long fibers is, of necessity, operated at a much slower speed to prevent degradation of the fibers. The nose bar and lickerins are set to obtain the optimum opening relationship for the fibers being processed, by known techniques.

The fibers that are individualized by the lickerins are acted on by separate high-velocity, turbulent air streams that are directed against the lickerin clothing at a junction adjacent its respective nose bar. The flow of air to each lickerin is regulated to control the quantity and uniformity thereof. The high velocity air streams are directed past the lickerins at a faster speed than the peripheral speed of the lickerins to assist the centrifugal forces imposed on the fibers by the lickerins in the doffing of the fibers from the lickerins, and entrain and convey the individualized fibers. The separate air streams are impelled toward one another and are subsequently brought together into a common highspeed air stream in a centrally disposed mixing zone defined by and between the spaced lickerins. In the mixing zone, the entrained fibers, still under the inertia set up by the high-velocity air streams and the centrifugal forces imposed on the fibers due to the high speed operation of the lickerin, are intermixed uniformly, so that they can later be air-laid into a nonwoven web of intermixed, randomly oriented, long and short fibers.

In the process of the present invention, the fibers entrained in the separate gaseous streams have a trajectory including a component impelling them toward one another, as well as a component directing them toward the mixing zone. Although the fibers are transported by the separate gaseous streams to the mixing zone, the fibers have sufficient kinetic energy by virtue of their mass and velocity, so that the fibers continue to travel at least in part in the direction of the initial trajectory because of their inertia. In consequence of this, the component of motion of the fibers toward one another causes them to combine in an intimate mixture of fibers when the air streams collide and intermix in turbulence into a common stream.

The common air stream is produced by the cooperative action of the fast moving air streams drawn through the system by a large suction generated within a fiber condensing means located at the terminal end of the mixing zone plus the air generated by the rotary action of the oppositely rotating high-speed lickerins. The combined stream in a state of turbulence transports the mixed fibers through the mixing zone to a condensing means where the fibers are deposited to build up a web of the desired thickness.

Different types of webs can be obtained with the apparatus of the present invention by introducing a baffle into the flow paths of the separate air streams in advance of the intermingling thereof. The baffle may be positioned to partially block the intermixing of the air stream and thus affect the blending of the entrained fibers in the mixing zone.

In one embodiment of the instant invention where the apparatus is fed wood pulp and rayon fibers and the air volume to fiber volume ratio in the common air stream is in the order of 5,000 to l, and the baffle does not block the separate air streams, a nonwoven web of randomly oriented pulp and rayon fibers, in substantially homogeneous intermixture is formed. With the same operating parameters, except with the baffle partially blocking the intermixing of the separate air streams, a web is formed having a layer of randomly oriented wood pulp fibers on one side, a layer of randomly oriented rayon fibers on the other, and an intermediate layer that is a homogeneous blend of randomly oriented wood pulp and rayon fibers.

The position of the baffle in the fiber mixing region determines the thickness of each of the aforementioned layers. It is possible to operate the apparatus of the present invention with the baffle fully extended, i.e., into a position immediately adjacent the condenser. With this arrangement, there will be no intermediate layer of homogeneously blended fibers and a web made up of two separate layers of different fibers that are interlaced only at the region of their interface will be formed.

The apparatus of the present invention can also be used to form still different types of webs, depending on the ratio of the volume of air to the volume of fiber in the duct carrying the common air stream through the system and the position of the baffle. It has been found that with the apparatus of this invention used with the baffle retracted, i.e., so that it does not block the mixing of the fibers, and a volume of air to volume of fiber ratio in the order of l2,000 to 1, or greater, a web is formed that has a predominance of one fiber at one face and a predominance of a second fiber at the other face of the web and a transition zone between the faces, wherein the fiber, which predominates at one face diminishes progressively from that face towards the other face, and vice versa. When the baffle is introduced into the system and the volume of air to volume of fiber ratio is in the order of 12,000 to l, or more, homogeneously blended, and other types of nonwoven webs can be formed. The process utilizing such high volume of air to volume of fiber ratios, i.e., 12,000 to l, or more, and the novel products formed thereby are disclosed and claimed in an application entitled Web bent characteristics, and so forth. The thickness and weight of the nonwoven products being produced by the novel apparatus and method disclosed herein can vary depending on conventionally commercial requirements, but typically they will in the order of 700 grains to several thousand grains per square yard and with a thickness of from about one thirty-second to aboutl inch, or more, prior to any post-treating operation. The web thickness will vary depending on the feeding rate of the fibers and the speed at which the web is removed from the condensing zone.

The foregoing advantages and numerous other features and advantages of the invention will be more readily understood and appreciated in light of the following specification, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a cross-sectional view showing the main components ,of the apparatus forming part of the instant invention as taken along line 11 of FIG. 2;

FIG. 2 is an end elevational view of the apparatus illustrated in FIG. 1;

FIG. 3 is a fragmentary perspective view, partially in section, showing a portion of the condenser;

FIG. 4 is an enlarged sectional view taken along line 44 of FIG. 3;

FIG. 5 is a schematic view of the apparatus showing the baffle partially extended;

FIG. 6 is a view showing the baffle in a more fully extended position;

FIG. 7 is a view showing the baffle in the fully extended position wherein it is located immediately adjacent a condenser;

FIG. 8 illustrates a randomly oriented, fully homogeneous web;

FIG. 9 shows a web having outer layers made of separate fibers and an intermediate homogeneous mixture of the two fibers;

FIG. 10 is a view showing a two-layered web; and

FIG. 11 is a web having a preponderance of a different type of fiber on each of the faces and a transition zone, such that the fiber type which predominates at one face diminishes in predominance from the face at which it predominates to the face at which the other fiber type predominates.

DETAILED DESCRIPTION OF THE INVENTION While this invention is susceptible of embodiment in many different forms, there are shown in the drawings and will herein be described in detail only preferred embodiments of the invention and modifications thereof, with the understanding that the present invention is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiments illustrated. The scope of the invention will be pointed out in the'appended-claims.

Referring first to FIG. 1, there is illustrated a crosssectional view of the web forming apparatus with parts broken away to show the relationship between the various components thereof. The apparatus will be illustrated and described as being used for blending wood pulp fibers and rayon, but it could obviously be used to blend two different fibers, or identical fibers.

In the drawings, the apparatus includesa main frame and subframe components, which, for the sake of simplicity and brevity, will be identified by reference letter F.

Reference will first be made to the left-hand, or wood pulp side of the system.

Wood pulp is introduced into the system in the form of a pulpboard 310, which is directed between a plate 311 and a wire wound feed roll 312. Connected to the lower part of the plate 311 is a nose bar 313 for providing an anvil against which the pulpboard is directed during the individualizing step. The nose bar 313 has a sidewall 314 that can be made relatively flat, since, due to the integrity of the pulpboard, it is unnecessary that the nose bar 313 be designed to more precisely direct the pulpboard to the lickerin 317 that is used to individualize the pulpboard into short fibers. The bottom wall 315 of the nose bar 313 is angularly disposed relative to the sidewall 314 and is spaced a short distance from the teeth 316 of the lickerin 317 to define a passage 318 through which the pulpboard is moved during the individualizing operation. The pulpboard is individualized into short wood fibers by the teeth 316 of the lickerin 317 acting on the pulpboard directed into position to be contacted by the teeth by the nose bar 313.

The feed roll 312 is journalled in a bracket 319 that is eccentrically mounted at 320 to permit adjustment of the feed roll relative to the pulp lickerin 317 and nose bar 313. The bracket 319 and feed roll 312 are resiliently biased to direct the pulpboard toward the nose bar 313 by a spring 322 that is located between bracket 319 and head 324a of bolt 324 that extends through a hole in the bracket 319, and is secured in place in plate 311. The pivotal movement of the bracket 319 is limited by a set screw 328 that is threaded into and through bracket 319 and engages plate 311. The spring 322 biases feed roll 312 into contact with pulpboard 310 to insure that the pulpboard is fed into position to be engaged by lickerin teeth 316. This design accommodates varying thicknesses of material that can be used in this system.

The feed roll 312 is secured to a shaft 330 that is suitably supported for rotation by a variable drive means, a portion of which is shown schematically in FIG. 2. The details of the drive means are not important to the present invention. The speed at which the feed roll is operated is determined by the rate at which pulp is to be fed into the system. A number of the mechanisms employed for supporting the rolls, lickerins, and so forth, are shown generally in FIG. 2 and they will be referred to when they will aid in understanding the present invention.

During the operation of the novel apparatus, the pulpboard 310 is fed into position to be engaged by the lickerin teeth 316 adjacent the nose bar 313. The lickerin 317 is mounted on shaft 331, which is driven at a very high speed by suitable drive means to individualize the pulpboard into short fibers. The drive means, to-

gether with shaft 331, comprises means for rotating lickerin 317. In an exemplary embodiment, the lickerin 317 is driven at a speed of 6,000 rpm. and produces a large throughput of pulp fibers without adversely affecting the fibers. v

The lickerin teeth 316 fray the pulpboard until the fibers are loosened therefrom, after which the teeth comb the short fibers out of the board. The clothing on the lickerin is designed to act on the'particular fiber and has the optimum tooth profile for the specific material it is processing. Each successive tooth has more opening action than the one before, which facilitates individualizing and when operated at an optimum speed greatly minimizes, if not totally prevents, clumps and salt from being extracted from the board.

The pitch and height of the teeth used on the lickerin for the pulpboard may vary, good results being obtained with a tooth pitch of about three thirty-seconds inch to about one-half inch and a tooth height of about three thirty-seconds inch to about one-half inch. The angle of the teeth of the lickerin for the pulpboard may also vary, generally within the limits of about l0 to about +l0. A positive angle for the teeth of the pulpboard lickerin which is standard in the industry, viz., +10, may be used in accordance with the invention, but this is not preferred. In general, it is preferred that the angle of the teeth be positive and be below +l0.

After the wood fibers are individualized by the lickerin 317, they are entrained in a turbulent air stream and directed through a duct 332 formed between the lickerin teeth 316 and a sidewall 333, which duct 332 leads into a mixing zone 334.

Referring now to the rayon fiberizing system which i is illustrated on the right side of FIG. 1, there are shown mechanisms that control the feeding of the rayon to the system. A number of the mechanisms used in processing the rayon are similar to those used on the pulp side of the system and where they are identical they are given the same numbers.

The rayon, which usually comes in the form of a carded batt 335, has no integrity and must be positively directed to the clothing of the rayon lickerin 338 to insure that the rayon lickerin teeth 339 will pick the rayon up from a rayon source 335. To this end, the nose bar 336 used with the rayon wire wound feed roll 337 differs from the pulp nose bar 313. The nose bar 336 is curved at 336a to essentially conform to the adjacent circumference of the rayon feed roll 337. The rayon fibers picked up from the rayon source are positively maintained in position relative to the feed roll 337 until the fibers are disposed immediately adjacent the teeth 339 of the rayon lickerin 338, which teeth will then serve to comb the fibers from the rayon source. The rayon lickerin is mounted on shaft 341, which is driven at a high speed by suitable drive means (not shown). The drive means, together with shaft 341, comprises means for rotating lickerin 338. A speed which can generally be used without seriously adversely affecting the fibers is 3,000 rpm.

The teeth of the rayon lickerin usually have a lower tooth height and pitch than the pulp lickerin. The pitch and height of the teeth used on the lickerin for the rayon may vary, good results being obtained with a tooth pitch of about one-eighth inch to about onefourth inch and a tooth height of about one-eighth inch to about one-fourth inch. The angle of the teeth of the lickerin for the rayon may also vary, generally within the limits of about l0 to about +20. The individualized rayon fibers are then air-conveyed into duct 340 located between sidewall 342 and lickerin 338, which duct 340 leads into mixing zone 334. The randomly oriented wood pulp and rayon fibers in the mixing zone 334 are then directed through duct 352 onto a condenser 350 where they form a web.

The movement of the air streams flowing through the system and its action on the fiber particles to effect the doffmg, blending and condensing that takes place subsequent to the individualizing will be covered in detail hereinafter.

In the process of the present invention, the length of the fibers in the condensed nonwoven web may be varied as desired by varying one or more conditions in the process. These conditions include, (a) the method used to open the fibers, as by adjusting the height and angle of the teeth, (b) the rate at which the fibers are opened and entrained, and (c) the method and rate of feeding the fiber source to the fiber opening and entraining step.

While the lickerins, nose bars, and fiber receiving means have been shown in a fixed position, These mechanisms may also be made adjustable relative to the frame F if this is desired.

The doffing of the fibers from the

lickerins

317, 338, the air entrainment of the previously individualized fibers, the conveying of the fibers through the

ducts

332, 340 into the mixing zone 334, and the conveying of the intermixed fibers through duct 352 to condenser 350 are accomplished by high velocity, turbulent air that is introduced into the systemby being pulled in through

parallel passages

344, 346 by a suction fan (not shown).

The .

parallel flow paths

344, 346 lead to lickerins 31-7, 338, respectively, to direct high velocity turbulent air in a uniform flow pattern against the

lickerin teeth

316, 339, respectively, to doff the fibers clinging thereto. The air with entrained particles therein then flows through

ducts

332, 340, respectively, into mixing zone 334 from where it flows through duct 352 and condenser 350. The blended randomly oriented fiber particles entrained in the air stream are deposited on the condenser in the form of a web.

The condenser 350 on which the fibers are formed into a web consists of an endless movable mesh screen conveyor 381 that is directed over four

pulleys

382, 384, 386, and 388. The position of pulley 388 can be adjusted to provide suitable tension on the screen. The conveyor is driven by suitable drive means (not shown). The conveyor 381 slides over the housing 348, which contains an aperture 349, through which the air is sucked into the housing and through conduit 389 that leads to the suction fan. The speed at which the condenser is moved will determine the thickness of the web being formed. For example, the thickness of the web will be increased by decreasing the web take-away speed, and vice versa.

The screen conveyor 381 leads to another conveyor belt 390 on which the web is carried to Another station for further processing. For example, the nonwoven webs' obtained by the process of the present invention may be post-treated by any suitable conventional bonding technique, e'.g., mechanical, or chemical, to bond the web and provide the requiredstrength and coherency characteristics for a given product. The particular type of bonding technique chosen will dependon various factors well-known to those skilled in the art, e.g., the type of fibers, the particular use of the products, etc. To this end, typical of the conventional techniques are web saturation bonding, suction bonding, foam bonding, print bonding, fiber bonding, fiber interlocking, spray bonding, solvent bonding, scrim bonding, viscose bonding, mercerization, etc.

For further details of the various bonding techniques, including the binders that can be employed, reference may be made to the aforementioned Lovgren application.

In order to help seal off duct 352 and maximize the efficiency of the suction fan being used, a pair of vertically extending

plate members

366, 368 are employed to define two outer wall portions of the duct 352 between the lickerins and the condenser. The lower portiorrof the duct 352 between the

plates

366, 368 and the condenser 350 are essentially sealed off by rollers 369 that are rotatably mounted on pivotally mounted

arms

370, 372 that are connected at their upper arms to a shaft 374. The weight of the rollers and arms tends to maintain the rollers in a sealing condition to minimize the introduction of air between the rollers 369 and the

plates

366, 368, and condenser 350.

Referring now to FIG. 4, there is illustrated a sealing mechanism that acts to seal the flow duct 352 along the edges of the web being formed. On each side, there is provided a floating seal 376 that is biased into contact with the web by a spring 378. The seal 376 is reciprocately mounted in a recess 379 defined in a side plate 380. This mechanism is duplicated on the opposite side to prevent introduction of air into the suction fan other than down through the flow ducts 352.

The condition and direction of the air flowing through the system has a very significant effect on the particular webs being formed. The air must have a uniform flow pattern through the system to aid in the formation of a uniform web. Also, the air should be in a turbulent condition and have a velocity greater than the peripheral speed of the lickerin which aids in doffing the fibers from the lickerin and prevents fiber clumping.

The ratio between the volume of air and volume of fibers passed through the system also has a significant bearing on the type of web that will be formed by the system. The air flow plays the important role that it does since it is in effect a pneumatic conveyor that deposits the fibers onto a condenser where they are formed into a'web. The quantities of fibers to be conveyed determine the amounts of air to be directed against the particular lickerin used for fiberizing a given material. Thus, for example, when forming a web of 90 percent (by weight) of wood pulp fibers and 10 percent (by weight) of rayon, a substantially higher quantity of air is needed to convey the wood pulp fibers than is needed to convey the rayon fibers.

In order to control the relative quantities of air directed to the pulp and rayon lickerins while insuring that the air so introduced aids in doffing the fibers from the lickerins, the

air passages

344, 346 are appropriately designed and located.

Air passage 344 is vertically disposed and the lower end is located immediately adjacent the teeth 316 of the pulp lickerin 317. The webs being formed by this system have substantial width and thus it is important that the-air flow across the axial length of the lickerin be uniform, so that the thickness of the .web will be constant. Also, the air acts to more effectively doff the fibers'from the lickerin if it is in a generally turbulent condition. To provide for turbulence while insuring that the air is uniformly distributed across the lickerin a wedge-shaped restrictor 354, secured to plate 356 that forms a sidewall of passage 344, is provided at the lower end of passage 344. The restrictor 354 defines a throat 358 through which the air pulled through the passage 344 must pass. This throat portion 358 brings about a low pressure drop and raises the velocity of the air before it contacts the pulp lickerin teeth 316. The

high velocity turbulent air directed into duct 332 from passage 344 in conjunction with the centrifugal forces imposed on the fibers due to the high speed of rotation of the lickerin 317 doffs wood pulp fibers from the lickerin teeth. The air in duct 332 entrains the fibers therein and conveys them to a mixing chamber 334. The duct 332 is directed downwardly at an approximately 45 angle and the high velocity air flowing therethrough will be directed into collision with the high velocity air flowing past the rayon lickerin, the path of which will be described below.

In a system where there is substantially less air needed to process the rayon fibers than to process the wood pulp fibers, it will be necessary to provide a substantial obstacle to the flow of air through the passage 346 to provide for the desired unbalanced air flow through the system.

In the passage 346, there is a restrictor provided in the form of an adjustable block 360, which has a substantial length and fills up a major part of passage 346. Between the plate 311 and block 360 there is defined anarrow passage 362. The block 360 results in setting up a turbulent condition for the air flowing into duct 340 and severely limits the quantity of air flowing thereto, as compared to the air flowing through the passage 344 and into duct 332. The position of block 360 can be adjusted by mechanism 364. The width of the

passageways

344, 346 can also be adjusted by the insertion of blocks by varying widths therein.

The high velocity turbulent air in duct 340 is moving faster than the peripheral speed of lickerin 338 and acts to doff the fibers from the rayon lickerin teeth 339 and entrain the fibers therein. Duct 340 is directed downwardly at a 45 angle with the result that the high velocity turbulent air flowing therethrough comes into impelling relationship with the entrained wood pulp fibers in the air stream moving downward through duct 332 into the mixing chamber 334. These air streams are moving at a very high rate of speed and the air is in a turbulent condition, with the result that when these two streams intermix, the fibers entrained therein will form a homogeneous blend of randomly oriented fibers. As the fibers are accelerated and entrained in the air streams flowing through

ducts

332, 340, they possess substantial kinetic energy because of their mass and velocity, and the inertia of the fiber tends to keep them moving along a path generally in the direction of their initial trajectory. The blended fibers then move down through the duct 352 onto the condenser 350, where a job made up ofa mixture of wood pulp and rayon fibers is randomly oriented more or less uniformly throughout the web, so that the web has substantially uniform strength characteristics lengthwise and crosswise thereof.

In practicing the present invention with the illustrated apparatus, a nonwoven web of homogeneously blended, randomly oriented fiber has been formed with a volume of air to volume of fiber ratio in the system being in the order of 5,000 to 1. Other types of webs can be formed with the illustrated apparatus by introducing a flow controlling member such as a baffle into the mixing zone, or by changing the volume of air to volume of fiber ratio.

The baffle 400, when introduced into the mixing zone 334, acts to at least partially block the intermixing of the separate air streams flowing through the

ducts

332, 340. With the baffle extended into the mixing zone, the entrained fibers in

ducts

332, 340 are prevented from intermixing until they pass below the bottom of the baffle. This controls the mixing of the high velocity air streams being impelled towards each other down

ducts

332, 340. The webs that are formed with the baffle extending into the mixing zone will vary depending on the depth of penetration of the baffle into the mixing zone.

The baffle 400 is in the form of a plate that extends the full width of the machine and, as shown, intersects the space between the lickerins. The baffle 400 is positioned through the action of a pair of gears 402 that mesh with racks 406 secured to the baffle 400 (FIG. 2). Leakage of air into the system past the baffle is prevented by sealing and guide

members

408, 410. The particular location of the baffle will determine how much blending will take place between the streams of fibers in

ducts

332 and 340. With the baffle located at an intermediate position in the mixing chamber and the volume of air to volume of fiber ratio in the order of 5,000 to 1, an isotropic web will be formed in which the bottom layer consists of substantially all wood pulp fibers, the upper layers consists of substantially all rayon fibers, and the intermediate layer is a homogeneous blend of the two fibers. As the baffle is moved further and further down toward the condenser, the intermediate layer of homogeneously blended fibers will become thinner and thinner and the outer sections of the web proportionately thicker. With the baffle all the way down, as shown in FIG. 7, a two-layered web of short and long fibers will be formed with the separate layers of different fibers interlaced only at the region of their interface.

The apparatus of the present invention can also be used to form still different types of webs, depending on the ratio of the volume of air to the volume of fiber in the duct carrying the common air through the system and the position of the baffle. It has been found that the apparatus of this invention used with the baffle retracted out of blocking relationship with the

ducts

332, 340 and the volume of air to volume of fiber ratio in the order of 12,000 to l, or greater, the fibers cross each other in the mixing zone and a web is formed having a preponderance of one fiber on one face of the web and a preponderance of a second fiber on the other face, and a mixture of fibers in a transition zone between the faces wherein the fiber which predominates at one face diminishes progressively from that face toward the other face, and vice versa. When the baffle is introduced into the system in which the volume of air to volume of fiber ratio is in the order of 12,000 to l, or greater, other types of nonwoven webs can be formed. For example, in the position shown in FIG. 5, where the baffle is in line with a plane drawn through the axis of the lickerins, a homogeneous, randomly oriented web is formed. The process of utilizing such high volume of air to volume of fiber ratios and the novel products formed thereby are disclosed and claimed in the aforementioned commonly owned Ruffo and Goyal application.

FIGS. 8-10 schematically illustrate some of the various types of webs that can be formed with the illustrated apparatus. FIG. 8 is intended to be a graphic illustration of a fully homogeneous web W. FIG. 9 illustrates a cross section of a nonwoven web 412 that is made up of three layers that are interlaced at their interface to form a web. The web 412 includes a layer 414 that contains essentially all staple fibers, a layer 416 of pulp fibers and a layer 418 which is a homogeneous blend of staple and pulp fibers. FIG. 10 illustrates a cross section of a web 434 made up of separate layers of staple fibers 436, and pulp fibers 438 which are interlaced at their interfaces. FIG. 11 illustrates a cross section of a web 440 in which the upper layer 442 has a predominance of pulp fibers and the bottom layer 444 has a predominance of staple fibers, and a transition zone therebetween in which the predominance of staple fibers decreases as it approaches the predomi nantly pulp layer 442 and the predominance of pulp fibers decreases as it approaches the predominantly rayon layer 444.

The following examples apply to the illustrated apparatus.

Example 1. A nonwoven web of a homogeneous blend of randomly oriented short pulp fibers and staple rayon fibers was formed in which, by weight, 90 percent of the fibers were pulp and 10 percent of the fibers were rayon.

The short fibers were extracted from pulpboard and the rayon fiberscame from a rayon picker lap in which the average fiber length was l-9/l6 inches, with a denier of 1.5.

Lickerins

317 and 338 were approximately 9% inches in diameter and were rotated at about 6,000 and 3,000 rpm., respectively, and the lickerins were spaced from one another by about 1% inches.

Lickerins

317 and 338 were spaced from duct walls 333 and 342, respectively, by about three-fourths inch.

Lickerins

317 and 338 were about l8 inches long and a total of 700 pounds per hour of .fibers were fed to the lickerins.

Deflector plates

366 and 368 were spaced from one another by about 4% inches. The average volume ratio of air to fiber was approximately 5,000 to l in the common air stream.

With the web take-away mechanism operated at a speed of 125 feet per minute, and with baffle 400 in the withdrawn position, a homogeneous web of randomly oriented fibers was produced having a weight of approximately 4,000 grains per square yard.

Example 2. The basic machine parameters of Example l were repeated, with the exception that the fiber feed was controlled to provide a feed rate of 180 pounds of fibers per hour 50:50 (by weight) mixture of wood pulp and rayon fibers, and the process employed a 70,000:l volume ratio of total gas to total fiber in the combined stream as disclosed in the above mentioned Ruffo et al. application. Also, lickerin 317 was rotated at about 5 ,000 rpm. The resulting web weighed approximately 550 grains per square yard, and was removed from the condensation zone at approximately 150 feet per minute.

With the above volume of air to volume of fiber ratio, and the divider plate 400 withdrawn, the resulting web was found to'consist of a predominance of rayon fibers at one face of the web and a predominance of wood pulp fibers at the opposing face of the web, with a decreasing amount of wood pulp and rayon fibers from the faces at which they predominate, respectively, to the opposed faces. This transition feature was found to be substantially uniform from face to face.

Example 3. The machine parameters of Example 3 were essentially the same as those in Example 2, except that an 80:20 (by weight) mixture of short wood pulp fibers and staple rayon fibers were fed to the respective lickerins. The wood pulp feed rate was approximately 1,000 pounds per hour and the rayon feed rate was approximately pounds per hour. Also, the baffle 400, having a thickness of about one-fourth inch, was positioned with the lower end thereof essentially located at the level of the plane defined by the axes of the lickerins. The combined air stream had a total air to total fiber volume ratio of approximately 30,000 to 1, as disclosed in the above mentioned Ruffo et al. application. The take-away mechanism was adjusted to provide a take-away speed of approximately 550 feet per minute, and the resulting web had a weight of approximately 1,400 grains per square yard.

The resulting web was found to be a homogeneously blended nonwoven web of randomly oriented fibers. The crossover product, such as that obtained in Example 2, was prevented because of the degree of interference of the baffle 400 with the separate gas streams.

I claim:

1. The method of forming a nonwoven web comprising the following steps:

1. providing at least two separate sources of fibers,

2. feeding each fiber source to the inlet of a confined separate fiber flow path, said paths converging toward one another and being in communication with a common fiber mixing zone and each fiber flow path having a fiber outlet leading to said common fiber mixing zone,

3. individualizing the fibers received from each separate source and introducing the individualized fibers from each separate source into one fiber flow path through the fiber inlet thereof,

4. providing a restricted opening upstream of the fiber outlet of each fiber flow path for directing a separate gaseous stream through each of said restricted openings with an impelling force to (a) entrain the individualized fibers in their respective streams while the fibers are in their respective flow paths, and (b) convey the entrained fibers with an impelling force along said converging flow paths and beyond said outlets and into said mixing zone to forcibly intermingle at least some of the fibers in one gaseous stream with at least some of the fibers in another gaseous stream,

S. applying centrifugal forces to the fibers from each source in each fiber flow path and in said mixing zone to aid in entraining the fibers in their respective gaseous stream and to aid in the intermingling of the fibers in the common mixing zone,

6. applying a driving'force to said gaseous streams to (a) cause said gaseous streams to flow through said restricted openings, (b) accelerate the movement of the entrained fibers through their respective flow paths and impel-the'fibersinto said mixing zone with at least some of the fibers from each flow path having a component of motion directed toward fibers from another flow path, and (c) accelerate the fibers through said mixing zone to a de positing zone, and

7. collecting the fibers in the depositing zone to form a web of nonwoven fibers.

2. The method of claim 1 wherein the separate gaseous streams are controlled so that each stream is in a turbulent condition when it is directed through its respective restricted opening.

3. The method of claim 1 wherein one source of fibers is textile length fibers, and the other source of fibers is short fibers.

4. The method of claim 1 including the further step of controlling the location of the fiber outlet of each separate fiber flow path relative to said depositing zone to control the configuration of the common fiber mixing zone and the degree of intermingling of said at least some fibers and to thus determine the type of web to be formed.

5. The method of forming a nonwoven web comprising the following steps:

1. providing at least two separate sources of fibers,

2. feeding each fiber source to the inlet of a confined separate fiber flow path, each path being in communication with a common fiber mixing zone and each fiber flow path having a fiber outlet leading to said common fiber mixing zone,

3. individualizing the fibers received from each separate source and introducing the individualized fibers from each separate source into a fiber flow path through the fiber inlet thereof,

4. introducing a separate high speed gaseous stream into each fiber flow path upstream of the fiber outlet thereof to (a) entrain the individualized fibers in their respective streams while the fibers are in their respective flow paths, and (b) convey the entrained fibers with an impelling force beyond said outlets, into said mixing zone, and to a depositing zone, with at least some of the fibers in one gaseous stream entering said mixing zone with a component of motion directed toward at least some of the fibers in another gaseous stream to forcibly intermingle said at least some fibers,

5. controlling the location of the fiber outlet of each separate fiber flow path relative to said depositing zone to control the configuration of the common fiber mixing zone and the degree of intermingling of said at least some fibers and to thus determine the type of web to be formed, and

6. collecting the fibers in the depositing zone to form a web of nonwoven fibers.

6. The method of claim 5 wherein said controlling step is performed by at least partially blocking the intermixing of said gaseous streams.

7. The method of claim 5 wherein the step of introducing said gaseous streams is performed by independently controlling individual gaseous streams for each source of fibers.

8. The method of claim 5 in which one fiber source is a source of textile length fibers and the other fiber source is a source of short fibers.

8. The method of claim 5 in which the collecting step is performed by applying a suction to a foraminous fiber receiving member at said depositing zone, whereby said fibers are retained at a relatively high velocity prior'to depositing on the fiber receiving member.

10. Web forming apparatus comprising: frame means; means for feeding a fibrous material to a first fiberizing station at a first location on said frame means; means for feeding a fibrous material to a second fiberizing station at a second location on said frame means; means defining a mixing zone between said fiberizing stations, said mixing zone having a fiber inlet end and a fiber outlet end; a first lickerin located adjacent the inlet end of said mixing zone; a second lickerin located adjacent the inlet end of said mixing zone; means mounting said lickerins in spaced parallel relationship on said frame means; means rotating each lickerin at its respective fiberizing station in fiber-removing relationship with respect to its respective fibrous material to open said fibrous materials and produce supplies of individualized fibers through the inlet end of said mixing zone; means for providing air streams for doffing the fibers from the lickerins and for initially directing said supplies of doffed fibers toward one another and to said mixing zone; a flow controlling member; means mounting said flow controlling member for movement relative to said mixing zone to control the extent to which said gaseous streams intermix, including means for moving said flow controlling member along a path that bisects the space between said lickerins; and fiber collecting means adjacent the fiber outlet end of said mixing zone for accumulating fibers to form a web.

11. Apparatus for forming a non-woven web of nonwoven fibers from at least two sources of fibers: a pair of lickerins; means rotatably mounting said lickerins in spaced parallel relationship with one another, so that the adjacent facing surfaces of said lickerins define boundary walls of a fiber mixing zone; means for rotating said lickerins in opposite directions; means for feed ing each source of fibers into contact with its respective lickerin whereby each lickerin individualizes fibers it receives from its respective source; means, including a portion of the periphery of each of said lickerins upstream of the facing surfaces of the lickerins that define the boundary walls of the mixing zone, defining separate duct means having a fiber inlet adjacent the positionwhere the fibers are individualized and a fiber outlet opening into said fiber mixing zone; means providing a restricted opening adjacent each lickerin, each restricted opening communicating with one of said separate duct means upstream of the fiber outlet thereof; means for impelling separate gaseous streams through each of said restricted openings and for directing said gaseous streams into its respective duct means and against the associated lickerin to (a) doff at least some of the fibers from each lickerin, (b) entrain the doffed fibers within the said duct means, and (c) convey the entrained fibers beyond the fiber outlet of each duct means and into said fiber mixing zone to forcibly intermingle at least some of the fibers from one gaseous stream with at least some of the fibers in the other gaseous stream; and collecting means including a movable foraminous member communicating with said fiber mixing zone to collect said fibers and form a web of non-woven fibers.

12. Apparatus as set forth in claim 11 including passage means in communication with each of said restricted openings, and means in each-of said passage means for controlling the flow therethrough to insure that the required quantity of gas in turbulent condition is uniformly provided to its respective lickerin.

13. Apparatus as set forth in claim 11 including generally parallel wall members located adjacent the source of fibers for its associated lickerin defining passage'means in communication with each of said restricted opening, and flow restricting means in each of said passage means for controlling the flow of the gaseous stream to the lickerin to insure that the required quantity of gas in the prescribed condition is uniformly provided to its respective lickerin.

14. Apparatus as set forth in claim 13 including means for varying the position of at least one of said flow restricting means.

15. Apparatus as set forth in claim 11 including means for providing a flow control member at a preselected position between said lickerins to control the intermixing of said gaseous streams and the intermingling of fibers.

16. Apparatus for forming a now-woven web of fibers from at least two sources of fibers comprising: means rotatably mounting a lickerin for each source of fibers; means for rotating said lickerins; means for feeding each source of fibers into contact with its respective lickerin whereby each lickerin individualizes fibers from its respective source; means defining a mixing zone between said lickerins having a fiber inlet end and a fiber outlet end; fiber collecting means adjacent the fiber outlet end of said mixing zone; means for causing gas to flow against each lickerin, through said mixing zone and to said fiber collecting means to (a) doff the individualized fibers from each lickerin, (b) introduce the doffed fibers into the mixing zone through the inlet end thereof, and (c) to forcibly intermingle at least some of the fibers in the mixing zone prior to deposition on the fiber collecting means; a flow controlling member; and means mounting said flow controlling member at least for vertical movement relative to said mixing zone between said lickerins to control the degree of intermingling of said fibers.

17. Apparatus as set forth in claim 16 wherein the mounting means for said lickerins locates the lickerins with the axes thereof in a common plane, and wherein the flow controlling member is mounted for movement perpendicularly with respect to said common plane.

Claims

1. The method of forming a nonwoven web comprising the following steps: 1. providing at least two separate sources of fibers, 2. feeding each fiber source to the inlet of a confined separate fiber flow path, said paths converging toward one another and being in communication with a common fiber mixing zone and each fiber flow path having a fiber outlet leading to said common fiber mixing zone, 3. individualizing the fibers received from each sEparate source and introducing the individualized fibers from each separate source into one fiber flow path through the fiber inlet thereof, 4. providing a restricted opening upstream of the fiber outlet of each fiber flow path for directing a separate gaseous stream through each of said restricted openings with an impelling force to (a) entrain the individualized fibers in their respective streams while the fibers are in their respective flow paths, and (b) convey the entrained fibers with an impelling force along said converging flow paths and beyond said outlets and into said mixing zone to forcibly intermingle at least some of the fibers in one gaseous stream with at least some of the fibers in another gaseous stream, 5. applying centrifugal forces to the fibers from each source in each fiber flow path and in said mixing zone to aid in entraining the fibers in their respective gaseous stream and to aid in the intermingling of the fibers in the common mixing zone, 6. applying a driving force to said gaseous streams to (a) cause said gaseous streams to flow through said restricted openings, (b) accelerate the movement of the entrained fibers through their respective flow paths and impel the fibers into said mixing zone with at least some of the fibers from each flow path having a component of motion directed toward fibers from another flow path, and (c) accelerate the fibers through said mixing zone to a depositing zone, and 7. collecting the fibers in the depositing zone to form a web of nonwoven fibers.

5. The method of forming a nonwoven web comprising the following steps:

5. applying centrifugal forces to the fibers from each source in each fiber flow path and in said mixing zone to aid in entraining the fibers in their respective gaseous stream and to aid in the intermingling of the fibers in the common mixing zone,

6. applying a driving force to said gaseous streams to (a) cause said gaseous streams to flow through said restricted openings, (b) accelerate the movement of the entrained fibers through their respective flow paths and impel the fibers into said mixing zone with at least some of the fibers from each flow path having a component of motion directed toward fibers from another flow path, and (c) accelerate the fibers through said mixing zone to a depositing zone, and

8. The method of claim 5 in which the collecting step is performed by applying a suction to a foraminous fiber receiving member at said depositing zone, whereby said fibers are retained at a relatively high velocity prior to depositing on the fiber receiving member.

11. Apparatus for forming a non-woven web of non-woven fibers from at least two sources of fibers: a pair of lickerins; means rotatably mounting said lickerins in spaced parallel relationship with one another, so that the adjacent facing surfaces of said lickerins define boundary walls of a fiber mixing zone; means for rotating said lickerins in opposite directions; means for feeding each source of fibers into contact with its respective lickerin whereby each lickerin individualizes fibers it receives from its respective source; means, including a portion of the periphery of each of said lickerins upstream of the facing surfaces of the lickerins that define the boundary walls of the mixing zone, defining separate duct means having a fiber inlet adjacent the position where the fibers are individualized and a fiber outlet opening into said fiber mixing zone; means providing a restricted opening adjacent each lickerin, each restricted opening communicating with one of said separate duct means upstream of the fiber outlet thereof; means for impelling separate gaseous streams through each of said restricted openings and for directing said gaseous streams into its respective duct means and against the associated lickerin to (a) doff at least some of the fibers from each lickerin, (b) entrain the doffed fibers within the said duct means, and (c) convey the entrained fibers beyond the fiber outlet of each duct means and into said fiber mixing zone to forcibly intermingle at least some of the fibers from one gaseous stream with at least some of the fibers in the other gaseous stream; and collecting means including a movable foraminous member communicating with said fiber mixing zone to collect said fibers and form a web of non-woven fibers.

12. Apparatus as set forth in claim 11 including passage means in communication with each of said restricted openings, and means in each of said passage means for controlling the flow therethrough to insure that the required quantity of gas in turbulent condition is uniformly provided to its resPective lickerin.

13. Apparatus as set forth in claim 11 including generally parallel wall members located adjacent the source of fibers for its associated lickerin defining passage means in communication with each of said restricted opening, and flow restricting means in each of said passage means for controlling the flow of the gaseous stream to the lickerin to insure that the required quantity of gas in the prescribed condition is uniformly provided to its respective lickerin.