US3281902A

US3281902A - Methods for producing fibrous webs

Info

Publication number: US3281902A
Application number: US206308A
Authority: US
Inventors: Kalwaites Frank
Original assignee: Johnson and Johnson
Current assignee: Johnson and Johnson
Priority date: 1962-06-29
Filing date: 1962-06-29
Publication date: 1966-11-01
Anticipated expiration: 1983-11-01

Description

Nov. l, 1966 F. KALwAnTl-:s 3,281,902

METHODS FOR PRODUCING FIBROUS WEBS Filed Jue 29, 1962 5 Sheets-Sheet 2 T1# j f\\ T1 .Ir-""'MT INVENTOR. @14A/K KM WA/rfs BY 20 uw 77/wf/f ATTORNEY Nov. 1, 1966 F. KALWAITES 3,281,902

METHODS FOR PRODUCING FIBROUS WEBS Filed June 29, 1962 5 Sheets-Sheet 1 INVENTOR. /CAA/A/ /fm 1444/755 BY @ffm 7m ATTORNEY Nov. l, 1966 F. KALWAITES METHODS FOR PRODUCING FIBROUS WEBS 5 Sheets-Sheet 5 Filed June 29, 1962 INVENTOR.

fw 1Min-5 Fal/VK BY @am 7 M United States Patent O 3,281,902 METHODS FOR PRODUCING FIBROUS WEBS Frank Kalwaites, Somerville, NJ., assignor, by direct assignments, to Johnson & Johnson, New Brunswick, NJ., a corporation of New Jersey Filed June 29, 1962, Ser. No. 206,308 8 Claims. (Cl. 19-106) This patent application is ya continuation-impart of copending patent application Serial No. 783,869, filed December 30, 1958, and now abandoned.

The present invention relates to fibrous Webs and to methods and appa-ratus for making the same. M-ore particularly, the present invention is concerned with methods and .apparatus for making fibrous webs having enhanced drafting characteristics, increased cross strength and irnproved uniformity `of fiber distribution and web density.

Fibrous webs may be classified in many ways but the most common division is into two general classes namely: (1) carded webs in which the fibers are lmore or less generally aligned lin one direction, with .a predominant direction of fiber orientation in the machine or long direction; and (2) isotropic Webs in which the fibers are not aligned or predominantly oriented in any `one direction but are `disposed at random. Such isotropic webs have substantially the same physical properties and characteristics in all directions.

Carded webs, due to the alignment of the fibers in the long direction, have fair strength in that direction and, for example, may be processed or otherwise manipulated at low draft lby being pulled or drawn through textile finishing apparatus and the l-ike, without substantial loss of uniformity of fiber distribution or web density and without developing an excessive number of light, thin, weak spots in the web. No very serious production problems are therefore created in that respect. The cross `strength of such carded webs, unfortunately, is not as high as desired and is only a fraction of the long strength. This ydisparity of long and `cross strengths thus represents one of the drawbacks to the use of such carded webs.

Isotropic webs, on the other hand, have approximately equal Astrengths in the long and cross directions and thus do not have the ygreat disparity of directional strength which is present in carded webs. These webs, however, normally do not have the long directional strength present in carded webs and thus, for example, cannot be as readily pulled or drawn through textile finishing apparatus and the like. Substantial loss of uniformity of fiber distribution and web density occur and an excessive number of light, thin, weak spots in the web are formed even at low draft. Thus, a very serious production problem is created in that respect and the Ihandling of such isotropic webs is therefore rendered very diicult. Additionally, the uniformity of fiber distribution and web density in isotropic webs, particularly in the lighter grain weights, is not as good as the uniformity of carded webs. It is thus -seen that each type -of fibrous web lhas its own individual advantages and disadvantages.

It is therefore a principal object of the present invention to provide methods and apparatus for improving the properties of fibrous Webs by improving the drafting characteristics `and cross strength thereof, lessening the disparity between the long and cross directional strengths, and improving the uniformity of fiber distribution and web density, particularly in the lighter lgrain weights, whereby t-he advantages of each type of fibrous web will be `available in Vone web.

It has Ibeen found that 4such objects may be accompl'ished by `initially forming a carded fibrous web on a rotatable surface, such as the dof-ling cylinder of a carding machine, the carded fibrous web having at least a predetermined minimum Weight per square yard, and then transferring the carded fibrous web from that rotatable surface to a second rotatabk: surface, such as a worker roll, which is accurately spaced from the first rotatable surface and which has a much lower peripheral surface linear velocity of 4less than 45% of the peripheral surface linear velocity of the first rotatable surface.

As ya result of the abrupt reduction in velocity of the carded fibrous web, the individual fibers, which are in a massed condition on the d-offing cylinder, are even further crowded together and are curled and puffed up out of the planes in which they originally existed. As a consequence, these fibers become intertwined and intermeshed in many plane-s, whereby a three-dimensional bulky fibrous web of high loft and low density is created. This threedimensional fibrous web has many times the thickness normally associated with a fibrous web of the same weight per :square yard made lby other processes and is found to possess the desired properties and c-haracteristics previously mentioned.

When the fibrous web is removed from the second rotatable surface and is carefully studied, it is found that there is substantially no predominant `direction of fiber orientation, that the drafting characteristics have been enhanced, that the cross strength has been increased, and that the uniformity of fiber distribution and web density is excellent. Additionally, it has ibeen found that such procedures lend themselves to the manufacture of fibrous webs which can be more easily handled in subsequent finishing operations in that they can be pulled or drawn through textile apparatus without substantial loss of uniform-ity of fiber distribution or web density and without developing an excessive number of li-ght, thin, weak spots in the web, even at higher web tension and resulting higher web draft.

It has further been found that, if t-he improved fibrous web is transferred from the worker roll to another rotatable surface, such as a stripping or drafting roll which is accurately spaced from the worker roll and has a peripheral surface linear velocity greater than the peripheral surface linear velocity of the Worker roll, the over-all manufacturing production rate of the fibrous web may be increased to `such yan extent that the linear velocity or manufacturing production rate of the fibrous web, at the point -it leaves the stripper or drafting roll, may equal or even be greater than the linear velocity it possessed on the ldofiing cylinder. As =a consequence, very high linear manufacturing production rates for the fibrous webs are possible.

The fibrous web or layer which is processed to form the products of this invention may contain natural or synthetic, vegetable, animal or mineral fibers such as cotton, silk, wool, vicuna, mohair, alpaca, fiax, ramie, jute, abaca, etc.; synthetic or man-made fibers such as the cellulosic fibers, notably cuprammonium, viscose or regenerated cellulose fibers; cross-linked cellulosi-c fibers such as Corval and Topel; cellulose ester fibers such as cellulose acetate (Celanese) and cellulose tri-acetate (Arnel); the saponified cellulose ester fibers such as Fortisan and Fortisan-36; the polyamide fibers such as nylon 420, nylon 6 (polycaptrola-ctam), nylon 66 (hexamethylene diamine-adipic acid), nylon 610 (hexamethylene diamine-seb'acic acid), nylon 1l, (ll-amino undecanoic acid-Rilsan); protein fibers such as Vicara; halogenated hydrocarbon fibers such as Teflon (polytetrafiuoroethylene); hydrocarbon fibers such as polyethylene polypropylene, polybutadiene and polyisobutylene; polyester fibers such as Kodel and Dacron, vinyl fibers such as Vinon and saran; dinitrile fibers such as Darvan; nitrile fibers such as Zefran; acrylic fibers such as Dynel, Verel, Orlon, Acrilan, Creslan, etc.; mineral fibers such as glass, metal; etc.

The lengths of the fibers in the starting fibrous web may vary from about inch up to about 21/2 inches or more in length, depending upon the particular properties and characteristics required or desired in the resulting fibrous web. If desired, the fibrous layer may have added thereto from about l or 2% by weight up to a minor proportion, say, less than about 50% by weight and preferably less than about 25% by weight, of fibers other than those of textile length. These other fibers may be of papermaking length, which extend from about 3/8 inch in length down to about 1/16 of an inch or less in length, which shorter fibers normally are not used in convention-al methods of producing fibrous webs.

Illustrative of these short papermaking fibers rare the natural cellulosic fibers such as woodpulp and wood fibers, cotton linters, cotton hull shavings fibers, mineral fibers such as asbestos, glass, rock wool, etc., or any of the hereinbefore-mentioned natural or synthetic fibers in lengths less than :about As inch and down to about 1/16 of an inch or less.

The denier of the individual synthetic fibers referred to above is preferably in the range of the approximate thickness of the natural fibers mentioned and consequently deniers in the range of from about 1 to about 5 are preferred. Where greater opacity or greater covering power is desired, special fiber deniers of down to about or even about 1/2 may be employed. Where desired, deniers of up Ito about 5.5, 6, 8, l0, l5, or higher, may be used. The minimum and maximum denier are naturally dictated by the desires or requirements for producing a particular fibrous web, by the machines and methods for producing the same, and so forth.

The weight of the fibrous web or layer of starting material on the doffing cylinder may be varied within relatively wide limits above a predetermined minimum value, depending upon the requirements of the intermediate or the final products. A single, thin web of fibers, such 'as produced by a card and as presented by the doffing cylinder, may have a weight of from about 30 to about 250 or more grains per square yard and may be used in the application of the principles of the present invention. Within the more commercial aspects of the present invention, however, web weights on the dofiing cylinder of from about 30 grains per square yard to about 150 grains per square yard are contemplated. If heavier weights are desired, such as up to 1800 grains, for example, several of the individual webs may be combined into a laminated structure to obtain the desired weight. The product of one doffing cylinder may be doubled, tripled, etc., on itself to reach the heavier weight, or a pluralit of cards may be used for a similar purpose.

The invention will be more fully understood from the description which follows, taken in conjunction with the accompanying drawings in which there are illustrated preferred designs of machine and modes of operation embodying the invention. It is to be understood, however, that the invention is not to be considered limited to the constructions disclosed except as determined by the scope of the appended claims. In the drawings:

FIGURE 1 is a simplified, fragmentary, schematic view in elevation showing the general principles of operation of the present invention;

FIGURE la is a fragmentary plan view, showing the mechanical drive for the apparatus of FIGURE 1;

FIGURE 2 is a simplified phantom representation in plan view of an improved fibrous web of the present invention in which merely a few of the individual fibers are dyed and are shown, with the majority of the individual fibers undyed and not shown for purposes of clarity;

FIGURE 3 is a simplified phantom representation in perspective of an improved fibrous web of the present invention in which merely a few of the individual fibers are dyed and are shown, with the majority of the individual fibers undyed and not shown for purposes of clarity;

FIGURE 4 is a polar graph showing a comparison of the tensile strengths in arbitrary -units of (l) the invention fibrous web, compared to (2) a conventional isotropic web and (3) a conventional card web, all of the same web density and at 0% draft, taken at 15 increments around the circle; and

FIGURE 5 is a simplified, fragmentary, schematic View in elevation showing a modification of the apparatus of FIGURE 1.

In the embodiment of the invention illustrated in the drawings, a conventional textile card is used and comprises a conventional rotatable main cylinder (not shown) which is used to provide for the normal carding of the fibers fed to the card whereby the fibers are disentangled and the bunches or tufts of fiber are separated into individual fibers. The initial attenuating of the fibers into an aligned condition takes place on the surface of Athe main cylinder and the individualized fibers are sparsely spread over the rotating surface in an amount weighing but a few grains per square yard.

These substantially individualized fibers which do not constitute a self-sustaining fibrous web are presented to a dofiing cylinder 10 which rotates at a much lower peripheral surface linear speed than the main cylinder. This speed differential creates a condensing of the individual fibers on the main cylinder into a thin, fibrous carded web weighing from about 30 grains to about 250 grains per square yard on the peripheral surface of the rotatable doffiing cylinder 10.

Immediately adjacent the dofing cylinder 10, and approximately at the position where the fibrous web formed thereon is conventionally removed by the usual textile doffing comb, is a cylindrical, rotatable worker roll 12, This worker roll 12 is the same width as the dofiing cylinder 10 but has a much smaller diameter which is in the range of from about 2 inches to about l2 inches and preferably from about 3 inches to about 8 inches. The worker roll is preferably covered with metallic clothing, although card fillets are satisfactory for some operations.

The worker roll 12 is adjustably and accurately positioned with respect to the dofiing cylinder 10 and the clearance between their peripheral surfaces is on the order of from about 0.005 inch to about 0.175 inch and preferably from about 0.007 to about 0.100 inch. The direction of rotation of the worker roll 12 is opposite to the direction of rotation of the dofiing cylinder 10 and is counterclockwise, as illustrated by the directional arrow.

The purpose of the worker roll is to remove the fibrous web from the surface of the dofiing cylinder and work the fibers thereof into a desired condition. In order to do so and accomplish the desired objects of the present invention, it has been established that, not only must the clearance between the rotatable peripheral surfaces be accurately maintained but the ratio of the peripheral surface linear velocity of the dofiing cylinder 10 to the worker roll 12 must be at least 2%zl, or putting it in reverse fashion, the peripheral surface linear velocity of the worker roll 12 must be less than 45% of the peripheral surface linear velocity of the dofiing cylinder 10.

If the clearance between the rotatable surfaces is not maintained and the peripheral surface linear velocity of the worker roll 12 is increased above the values specified above, the fibers of the web on the dofiing cylinder will not be satisfactorily transferred to the worker roll nor will they be properly worked during such transfer and the objectives of the present invention will not be obtained.

The exact mechanism whereby the carded we'b is transferred from the dofiing cylinder to the worker roll 12 and worked during such transfer whereby the objectives of the present invention are realized has not been definitely established. However, it has been established that, when the clearance between their rotatable peripheral surfaces is accurately maintained and the speed differential is sufficiently great, the objectives are obtained. It is known, however, that the carded fibers are transferred and are curved or puffed up and formed into circular, helical, spiral, or sinusoidal shapes during such transfer whereby they assume three-dimensional configurations which extend out of the plane of the web whereby the bulk and loft thereof are increased and the web density is decreased. Simultaneously, the cross strength of the resulting web is increased and the uniformity of fiber distribution and web density is improved.

The extent of the curling or puffing up of the fibers is illustrated in phantom, FIGURES 2 and 3. In these figures, merely a few individual fibers in the fibrous web are dyed and act as tracer fibers whereby individual fibers can be inspected even when intermeshed and intertwined with many other similarly curled fibers. The fibers which are undyed are not shown for purposes of clarity but it can `be safely assumed that they, too, are curled like the dyed fibers.

It is to be noted that the individual fibers are highly curled and twisted and that major portions thereof do not lie on any particular surface or in any particular plane.

One end of the fiber quite often is located at one side of the fibrous web with the main body of the fiber extending to the other side of the fibrous web and then back to the original side, etc.

Such a configuration is to be contrasted to the fibers which are present in a conventional carded web. In such a web the fibers have a predominant direction of fiber orientation and, although the fibers do not lie in perfectly straight lines, they are aligned when considered in gross. The major portion of these individual fibers each lie essentially in a s-ingle plane and do not meander back and forth within the fib-rous web in the manner of the fibers in FIGURES 2 and 3.

The curled and twisted fibers of the fibrous web of the present invention are Ialso to 4be contrasted to the fibers in a conventional isotropic web. In such a web, the individual fibers are disposed at `random and do not have any predominant direction of fiber orientation. The major portion of these individual fibers each lie essentially in a single plane and do not meander back and forth in the manner of the fibers of FIGURES 2 and 3.

It is believed that the meandering configuration of the fibers of the fibrous web shown in FIGURES 2 andr3 is responsible for the desired properties and characteristics. For example, a conventional isotropic fibrous web not made by the present invention may be drafted only a very small amount, say up to about or 50%, before light, thin, weak spots appear and there is a substantial loss of uniformity of fiber distribution and web density. Holes quite often appear in which there are substantially no fibers at all. Such a non-uniform fibrous web is -of little or n-o commercial value.

In the case of a conventional carded web, drafting is also possible only to a low degree, say to about or 70%, at which time light, thin, weak spots or even holes appear in the fibrous web and there is a loss of uniformity -of fiber distribution and web density. On the other hand, in the case of the fibrous web illustrated in FIGURES 2 and 3 made |by the processes and apparatus of the present invention, such a web may be drafted to at least about 200% in the cross or long directions without developing 6 any light, thin, weak spots or holes or without developing non-uniformity of fiber distribution and web density. In some cases, satisfactory drafting, particularly in the case of long or machine direction, [has been accomplished to a degree as high as about 400%.

The importance of this improved drafting characteristic particularly in the machine direction is to Ibe appreciated when it is realized that substantially every fibrous web is subjected to a certain amount of tension whenever it is processed through textile apparatus. In the event that the fibrous web is weak and cannot resist deformation due to tension, the manufacturing process must be slowed dovm and precauti-on-s taken to avoid the application of undue tension and the resulting excessive draft. However, if a fibrous we'b is lsufficiently strong and can resist deformation -due to the application of tension, such a fibrous web can be processed at considerably greater speeds through textile apparat-us without requiring precautions to avoid undue draft.

It is to be observed, however, that, at this point in the operation, the linear manufacturing production rate has been drastically reduced inasmuch as the fibrous web on the worker roll 12 is moving forwardly at merely a small fraction, less than 45%, of the peripheral surface linear velocity of the carded web on the dofiing cylinder 10.

One way to compensate for this relative loss in linear production rate is to increase the feed of fibrous materials to the rnain cylinder `of the card and to increase the rotational velocity of the 4dofiinig cylinder proportionate-ly or to any desired speed, whereby the rotational velocity of the worker roll may similarly be increased up to 45% of the new velocity of the dofiing cylinder, provided the ratio of the linear velocities of the main cylinder to the doffing cylinder is maintained at a value satisfactory to give fiber transfer. In this way, the linear velocity of the web leaving the worker roll 12 may be increased su* stantially.

It is to be observed that such a procedure of increasing the feed of fibrous materials to the main cylinder and increasing the velocity of the dofiing -cylinder would lead t-o difficulties if a conventional dofiing comb were used. Such a doffing comb would, -most likely, not -be able to keep up with the increased -mass of fibers being forwarded by the dofiing cylinder at its increased velocity. A Worker r-oll, however, can keep up with such increased throughput and, as a consequence, the use of the worker roll 12 leads to advantages and benefits not available when a conventional dofiing comb is used.

Another method of increasing the linear production rate is also available and has the advantage that it combines an increased linear production rate with drafting of the web. .A stripper and/ or drafting roll 14 is provided immediately adjacent the side of the worker r-oll 12 opposite the dofiing cylinder. The ranges of the physical dimensions of the stripper and drafting roll may be similar to the physical dimensions of the worker roll. For example, the stripper roll 14 is also the same length as the doffing cylinder 10 and also has la diameter in the range of from about 2 inches to about 12 inches, and preferably from about 3 inches to about 8 inches. The stripper roll 14 is preferably covered with metallic clothing, although card fillets are satisfactory for some operations.

The stripper roll is independently driven and rotates in a counterclockwise direction, as illustrated, with a peripheral surface linear velocity which is equal to or preferably greater than the peripheral surface linear velocity of the worker roll 12. The peripheral surface linear velocity of the stripper roll may be increased, if desired, for example, to a value (1) eqn-a1 to or (2) greater than the peripheral surface linear velocity of the dofiing cylinder in which case the over-all production rate of the machine is maintained (1) unchanged or (2) even increased.

As a consequence, any web linear velocity or manufacturing production rate which is momentarily lost when the carded web is removed from the dofiing cylinder by the worker roll is regained when the fibrous web is transferred from the worker roll to the stripper roll. The ratio of the peripheral surface linear velocity of the stripper roll to the peripheral surface linear velocity of the worker roll is, of course, Iat least and preferably greater than 1:1 and is usually at least about 21/zz1. Within the more commercial aspects of the present invention, however, a range of from about ll/ztl to about 31/2z1 has been found advantageous, with ratios as high as about 5:1 being desirable in some cases.

The stripper roll is adjustably yand accurately positioned with respect to the worker roll and the clearance between their peripheral surfaces is on the lorder of from about 0.005 inch to about 1A inch and preferably from about 0.007 inch to about 0.100 inch. These clearances are irnportant in starting-up operations; once operations are in full force, the clearance may be increased, perhaps to l1/2 inch or more.

In the event that it is desired to remove the fibrous web from the worker roll and to process it further without involving the use of -a stripper roll, a downwardly directed conveyor belt 16 is provided and is mounted upon rotatable driving pulleys 18 and 20` and is so positioned with respect to the worker roll that it is capable of receiving the fibrous web therefrom and conveying it to a main conveyor belt 22 to be carried onwardly to be combined with other webs or other materials, or otherwise processed, as desired.

Such a procedure in which the fibrous web is removed from the worker roll results in relatively low linear manufacturing production rates, because of the necessary low speed of the worker roll 12. It is therefore preferred to remove the fibrous web from the stripper roll 14 which rotates at a considerably higher surface peripheral linear velocity. A second conveyor belt 24 mounted on driving rotatable pulleys 26 `and 28 is therefore provided and is so positioned with respect to the stripper roll 14 as to be capable of receiving the fibrous web therefrom and conveying it to the main conveyor belt 22 whereon it may be combined with other Webs or other materials, or otherwise processed, as desired.

In FIGURE 1a, there is illustrated a conventional mechanical driving arrangement for driving the dofling cylinder l0, the worker roll 12, and t-he stripper roll 14.

A eXible belt 11, driven by a suitable source of power (not shown) drives a pulley 13 mounted on a rotatable stub shaft 15. A pinion 17 mounted on the shaft 115 meshes with a gear 19 secured to the periphery of the doffing cylinder and drives the same. A sprocket 21 is also mounted on the shaft Iand drives a sprocket 23 by means of a sprocket chain 25. The sprocket 23 is mounted on a rotatable shaft 27 upon which the worker roll 12 is mounted. A gear 29 is also mounted on the shaft 27 and drives a gear 31 by means of an idler gear 32. The gear 31 is mounted on a rotatable shaft 35 upon which the stripper roll 14 is mounted.

The sprocket 21, the chain `25, and the sprocket 23 are removable and may be replaced by other sprocket and chain drives whereby the worker roll 12 may be driven at any desired linear speed relationship with respect to the dofiing cylinder 10. As pointed out previously, the peripheral surface linear speed of the worker roll must be less than Iabout 45% of the peripheral surface -linear speed of the doing cylinder, or, stating this in reverse fashion, the peripheral surface linear speed of the doffer cylinder must be about 2% times the peripheral surface linear speed of the worker roll. If desired, this multiplier ratio may be increased so that the doffer cylinder has a peripheral surface line-ar speed y10 or 25 times, or even 50 or 100 times, that of the worker roll. In such -a case, the openings and clearances of cooperating rotatable parts and the like are usually increased so that the heavier weight and thicker webs can be properly handled.

The weight and thickness of the fibrous web on the Worker roll is, therefore, increased so that it is considerably more than the weight and thickness of the fibrous web on the doffer. The increase in weight and thickness will always inherently be at least about 2% times as a minimum value, due to the peripheral surface linear velocity reduction from the doffer to the worker roll. The increase, however, may be greater than 21A times and may increase to 10 or 25 times, or even 50 or 100 times, depending upon the ratio of the peripheral surface linear velocity of the doffer and the Worker roll. Stating this in terms of percentages, the peripheral surface linear velocity of the worker roll may be less than about 45% of the peripheral surface linear -velocity of the dofling cylinder and be as low as 10% or 4%, or even 2% or 1%, depending upon the desires and requirements of the particular situation.

In a similar way, the

gears

29, 31 and 32 may be replaced by 4other gears whereby the speed relationship of the worker roll and the stripper roll may be changed within the speed relationships indicated previously. This, of course, changes the yardage production rate of the apparatus.

Such ya mechanical driving arrangement is a conventional mechanical driving arrangement and it is to be appreciated that substantially any other conventional mechanical driving arrangement can be substituted therefor Without affecting the essence of the inventive concept.

It is not essential `that the rolls employed in handling the fibrous web subsequent to its removal from the doffinig cylinder be provided with either metallic clothing or with card fillets. In FIGURE 5, there is illustrated a modification of the present invention in which some of the rolls are smooth. In FIGURE 5, there is illustrated a dofiing cylinder S0 and a Worker roll 52 which cooperate with each other and function in substantially the same manner as the dofiing cylinder 10 and the worker roll 12 of FIGURE 1. I-n IFIGURE 5, the dofling cylinder 50 and the worker roll 52 are covered with metallic clothing. The clearance between the rotatable peripheral surfaces of the doffing cylinder 50 and the worker roll 52 must also -be accurately maintained within th'e limits previously described. Additionally, the ratio of the peripheral surface linear velocity of the dofhng cylinder 50 to the worker roll 52 must also be at least about 2% to 1, or putting it in reverse fashion, the peripheral surface linear velocity of the Worker roll 52 must 'be less than about 45% of the peripheral surface linear velocity of the doing cylinder.

Immediately adjacent to the Worker roll 52 is a pair of relatively smooth-faced nip rolls 54 and 54' which cooperate to handle and ladvance lthe fibrous web after it has been removed from the worker roll 52. These nip rolls S4 and 54 have the same length as the d-ofiing cylinder 50 and the worker rol-l 52 but have much smaller diameters which are in the range of from about 2 inches to about 8 inches and preferably from Iabout 21/2 inches to about 6 inches. It is not essential that the nip` rolls 54 and 54 lhave the same diameters but, if they do have different diameters, arrangements should be made so that they rotate with substantially the same peripheral surface linear speed. The nip rolls 54 are preferably made of some relatively firm, metallic, material, usually steel, ibut any material having sufiicient strength, rigidity or generally similar surface characteristics may be used.

The nip rolls 54 and 54 are independently driven and rotate in the direction illustrated, with a peripheral sur face linear velocity which is equal to or preferably greater than the peripheral 'surface linear velocity of the worker roll 52. The peripheral surface linear velocity of Ithe nip rolls 54 and 54 may be increased, if desired, Ifor example, to la value either equal to or even ygreater than the peripheral surface linear speed of the dofling cylinder 50 in which case the overall yardage production rate of the machine is either maintained unchanged or even increased.

A pair of

doctor blades

56 and 58, mounted on doctor blade assemblies 60 .and 62 is provided to prevent the lapping of fibers on the nip rolls 54 and S4. 'Ilhese doctor blades 56 and 53 are in sliding contact with the nip rolls 54 and 54', in accordance with conventional practice. The doctor blade assembly 60 is mounted on a shaft 61 and is biased by light spring-means or otherwise, in the direction of the nip roll 54. The doctor blade assembly 62 is mounted on a shaft 63` and is biased by light springmeans or otherwise, in the direction of the nip roll 54.

Brush 64 is mounted adjacent the `doctor blade assembly `62 and is in light brushing contact with the worker roll 52 and serves to clean or clear the same. A rotatable scavenger roll -66 mounted Ion a lever 68 pivoted on a shaft 70 may also be used to contact the worker roll 52 to help in keeping it clear tof fibrous materials. A light spring 67 presses the scavenger roll 66 against Ithe worker roll 52. If desired, a slide yor apron 72 may be employed t receive .the brous web after it has passed through the nip rolls 54 and 54 to direct and guide it as required. 'Ilhe invention will tbe further illustra-ted in greater detai-l by the following specific examples. It should be understood however, that, lalthough these examples may describe in particular detail some of the more specific features of the invention, they are given primarily for purposes of illustration and the invention in its broader aspects is not to be construed .as limited thereto.

EXAMPLE I The starting fibrous material, as delivered from the doliing cylinder, is a 40-incl1 wide card web of viscose rayon staple fibers, weighing about 120 Igrains per square yard and contain-ing fibers having a length of -about 1%@ inches .and a denier of about ll/z. The peripheral surface linear velocity of the doffing cylinder is 80 yards p'er minute. The doing cylinder is covered with metallic clothing having 11 points per inch with 26 wraps per inch of cylinder.

The fibrous web is transferred to -a worker roll which is accurately spaced 0.035 inch from the dofling cylinder. The worker roll has a peripheral surface lin'ear velocity of 32 yards per minute. This is equivalent to .a 2l/2 :1 ratio. The diameter of the worker troll is 31/2 inches and it is covered with metallic Iclothing having 71/2 points per inch with about 22 wraps per inch of roll.

Examination of the fibrous web reveals that the cross strength thereof has a value of 1.4 pounds, as compared to the cross strength of 0.9 pound for a ysimilar fibrous web prepared from similar materials 'on similar equipment but removed from the dong cylinder by a conventional doiiinlg comb. Additionally, the product of this example `has excellent uniformity of liber distribution and web density therein, high bulk and loft and low density. Th'e web is capable of being drafted 200% in the long direction and in the cross direction without loss of uniformity of fiber distribution and web density and without developing light, thin, weak spots 'or holes.

The fibrous web is then transferred from the worker roll to a stripper roll which has a diameter of 31/2 inches and a peripheral surface linear velocity of 80 yards per minute. The stripper roll is covered with metallic clothing having 71/2 points per inch with 22 wraps per inch of roll.

The web is then removed from the 'stripper roll, positioned on a downwardly-directed conveyor belt `and carried to a main conveyor belt Whereon it is `combined with another similar l-grain web and consolidated with four 1Z0-grain carded webs, two on each side. The fibrous webs are then processed lby printing with a binder and drying on heated cans inthe usual manner. The resulting product is an excellent interlining fabric.

EXAMPLE II The procedures set forth in Example I lare followed substantially as set forth therein with the exception that the 31/2 inch diameter worker roll is replaced by a 7- inch diameter worker roll having a peripheral surface l0 linear velocity of 32 yards per minute. The worker roll is covered with metallic clothing having 71/3 points per inch and 24 wraps per -roll inch.

The results are similar to those obtained in Example I and the fibrous web is found to be similarly improved.

EXAMPLE III The procedures set forth in Example I are carried out substantially as set for-th -therein with the exception that the 31/2 inch diameter stripper and drafting roll is replaced by a 7-inch diameter stripper `and drafting roll having a peripheral surface linear velocity of y yards per minute. The stripper and drafting roll is cove-red with metallic clothing having 71/3 points per inch and 24 wraps per roll inch.

The results are similar to Ithose obtained in Example I and the fibrous web is found to be similary improved.

EXAMPLE 1V The procedures set forth in Example I are followed substantially as set forth the-rein with the exception that the peripheral surface linear velocity of the dofling cylinder is 80 yards per minute, the peripheral surface linear velocity of the stripper roll is y65 yards per minute and the peripheral surface linear velocity of the worker roll is 80 yards per minute.

The operation is unsatisfactory and -only partial dofing is accomplished. The bers are not completely transferred from the dofling cylinder to .the worker roll but accumulate and wrap on the dofng cylinder.

EXAMPLE V The procedures of Example I are followed supstant-ially as set forth there-in except that the liber feed is increased fand a velocity ratio lof 31/2 :1 is used.

The resulting web is doubled .as it `leaves the drafting roll and has a weight of 400 grains per squa-re yard. The long strength is 1.4 pounds and the cross streng-th is 1.4 pounds, measured at 0% draft. At 50% d-raft in the mach-ine direction, the long strength is 1.5 pounds and the cross strength is 1.0 pound. The drafting is continued Ito 156%, 270% 330% and 430% in the long direction and the drafted web is still visually uniform as regards fiber distribution and density. The-re are no streaks, holes, or thin, weak, light spots.

This improved isotropic web is to be contrasted to a conventional card web made of the same fibers and having the same web weight. The Ilong strength of the card web is 1.9 pounds but the cross strength is only 0.7 pound, measured at 0% draft. At 50% draft, the long strength is 1.96 pounds and the cross strength is only O M pound, .a commercially unacceptable value. rPhe drafting .is continued to 100% in the long direction. Streaks develop in the card web and uniformity of fiber distribution and web density is lost.

The comparison is continued w-ith the improved isotropic web being `contrasted to a conventional isotropic web such as made by `air deposition techniques described in U.S. Patents 2,676,363 and 2,676,364. The fibers used are the same as used previously and the web weight is the same. The long strength of the conventional isotropic web is 1.3 pounds and the cross strength is 1.2 pounds, measured at 0% draft. At 50% draft, the conventional isotropic web `has developed streaks; light, thin, weak spots have appeared; and uniformity of fiber distribution and web dens-ity is lost.

1 l EXAMPLE v1 The procedures -of Example V `are repeated, with the following results, as illustrated in FIGURE 4.

INVENTION ISOTROPIC WEB EXAMPLE VII The starting fibrous material, as delivered by the 27 inch diameter dofiing cylinder, is a 40 inch wide card web of greige unbleacfhed cotton fibers, weighing about 55 grains per linear yard. The apparatus illustrated in FIGURE 5 is employed. The peripheral surface linear velocity of the doffer is about 96 feet per minute.

The fibrous web is transferred to a .3l/z inch diameter worker roll which is accurately spaced 0.005 inch from the doffer. The worker roll is covered with metallic card clothing `and has a peripheral surface 'linear velocity of 12.8 feet per minute. This is equivalent to a web-condensing ratio of about 71/2 to 1.

T-he weight of the fibrous web on the worker roll is about 412 grains per linear yard and i-ts thickness is considerably increased. There is no predominant direction of fiber orientation but the fibrous web has increased cross strength and enhanced drafting characteristics. Additionally, lthe fibers have been individual-ized very well and the web uniformity is excellent.

The fibrous web is carried upwardly on ya portion of the periphery of the worker roll and then is drawn upwardly between the nip of two smooth-faced, springloaded nip rolls having diameters of 2 inches and 3 inches. The peripheral surface `linear velocity of the nip rolls is 16 feet per minute whereby some drafting is accomplished between the worker roll and the nip rolls. The overall reduction in peripheral surface linear velocity from the doffer to the nip rolls is 6 to l.

The fibrous web removed from the nip rolls weighs approximately 330 grains per linear yard. Upon examination, it is determined that the fibrous web has substantially no predominant direction of fiber orientation but has increased cross strength and enhanced drafting characteristics. The fibers are very well individualized and the web uniformity is excellent.

EXAMPLE VIII The starting fibrous material, as delivered by the 27 inch diameter dofiing cylinder, is a 40` inch wide card web of greige unbleached cotton fibers, weighing about 55 grains per linear yard. The apparatus illustrated in FIGURE 5 is employed. The peripheral surface linear velocity of the doffer is about 96 feet per minute.

The fibrous web is transferred to a 3l/2 inch diameter worker roll which is accurately spaced 0.010 inch from the doffer. The Worker roll is covered with metallic card clothing and has a peripheral surface linear velocity of about 3.2 feet per minute. This is equivalent to a web-condensing ratio of about 30 to 1.

The weight of the fibrous web on the worker roll is about 1650 grains per linear yard and its thickness is very much increased. There is no predominant direction of fiber orientation but the brous web has increased cross strength and enhanced drafting characteristics. Additionally, the fibers have been individualized very well and the web uniformity is excellent.

The fibrous web is carried upwardly on a portion of the periphery of the worker roll and then is pulled upwardly between the nip of two smooth-faced, springloaded nip rolls having diameters 0f 2 inches and 3 inches. The peripheral surface linear velocity of the nip rolls is 4 feet per minute whereby some drafting of the web is accomplished between the worker roll and the nip rolls. The overall reduction in peripheral surface linear velocity from the doffer to the nip rolls is 24 to 1.

The fibrous web removed from the nip rolls weighs approximately 1320 grains per linear yard. Upon examination, it is determined that the fibrous web has substantially no predominant direction of fiber orientation but has increased cross strength and enhanced drafting characteristics. The web has excellent fiber individualization and distribution and the web uniformity is very good.

All long and cross strengths are referred to in units of pounds for comparison purposes. More precisely, these units are pounds per inch of width per grains per square yard.

Although no motors, pulleys, belts, gears, or like means have been illustrated or described for driving the various cylinders and rolls at their desired or required speeds or with the rotations indicated by their directional arrows, it is to be appreciated that such has been done to keep the illustrations and description succinct and to avoid the introduction of matters which are well-known expedients in the art. Such driving means which are used are conventional and merely involve the application of well-known mechanical driving principles.

Although several specific examples of the inventive concept have been described, the same should not be construed as limited thereby nor to the specific values mentioned therein or the constructions described, but to include other values and other constructions as set forth in the claims appended hereto. It is to be understood that any suitable changes, modifications and variations may be made without departing from the spirit and scope of the inventive concept.

What is claimed is:

1. In a method of improving the cross strength and drafting characteristics of a fibrous web which comprises the steps of continuously carding fibers on a rotatable carding surface and transferring said carded fibers directly from said rotatable carding surface to projections lying in a rotatable surface having a much lower peripheral surface linear speed than that of said rotatable carding `surface to form a carded fibrous web on said rotatable surface, said carded fibrous web having a predominant direction of fiber orientation along the longitudinal axis thereof, the improvement which comprises: transferring said carded fibrous web directly from said rotatable surface to projections lying in a second rotatable surface closely adjacent to but spaced from said first-mentioned rotatable surface by a clearance of from about 0.005 inch to about 0.175 inch, said second-rotatable surface moving in the same direction as said first-mentioned rotatable surface at the point of closest adjacency and having a peripheral surface linear.velocity less than about 45% of the peripheral surface linear velocity of said first-mentioned rotatable surface to condense the fibrous web on the second rotatable surface so that it has at least about 21A times the weight it had on the first-mentioned rotatable surface but has increased cross strength, en-

hanced drafting characteristics, and substantially no predominant direction of fiber orientation.

2. In a method of improving the cross strength and drafting characteristics of a fibrous web which comprises the steps of continuously carding fibers on a rotatable carding surface and transferring said carded fibers directly from said rotatable carding surface to projections lying in a rotatable surface having a much lower peripheral surface linear speed than that of said rotatable carding surface to form a carded fibrous web on said rotatable surface, said carded fibrous web having a predominant direction of fiber orientation along the longitudinal axis thereof, the improvement which comprises: transferring said carded fibrous web directly from said rotatable surface to projections lying in a second rotatable surface closely adjacent to but spaced from said first-mentioned rotatable surface by a clearance of from about 0.005 inch to about 0.175 inch, said second rotatable surface moving in the same direction as said first-mentioned rotatable surface at the point of closest adjacency and having a peripheral surface linear velocity less than about 45 of the peripheral surface linear velocity of said first-mentioned rotatable surface to condense the fibrous web on the second rotatable surface so that it has at least about 21A times the weight it had on the first-mentioned rotatable surface but has increased cross strength, enhanced drafting characteristics, and substantially no predominant direction of fiber orientation; and transferring said fibrous web to a third rotatable surface closely adjacent to but spaced from said second rotatable surface and having a peripheral surface linear velocity at least equal to the peripheral surface linear velocity of said second rotatable surface.

3. In a method of improving the cross strength and drafting characteristics of a fibrous web which comprises the steps of continuously carding fibers on a rotatable carding surface and transferring sa-id carded fibers directly from said rotatable carding surface to projections lying in a rotatable surface having a much lower peripheral surface linear speed than that of said rotatable carding surface to form a carded fibrous web on said rotatable surface, said carded fibrous web having a perdominant direction of fiber orientation along the longitudinal axis thereof, the improvement which comprises: transferring said carded fibrous web directly from said rotatable surface to projections lying in a second rotatable surface closely adjacent to but spaced from said first-mentioned rotatable surface by a clearance of from about 0.005 inch to about 0.175 inch, said second rotatable surface moving in the same direction as said first-mentioned rotatable surface at the point of closest adjacency and having a peripheral surface linear velocity less than about 45% of the peripheral surface linear velocity of said first-mentioned rotatable surface to condense the fibrous web on the second rotatable surface so that it has at least about 2% times the Weight it had on the first-mentioned rotatable surface but has increased cross strength, enhanced drafting characteristics, and substantially no predominant direction of fiber orientation; and transferring said fibrous web to a third rotatable surface closely adjacent to but spaced from said second rotatable surface and having a peripheral surface linear velocity greater than the peripheral surface linear velocity of said second rotatable surface.

4. In a method of improving the cross strength and drafting characteristics of a fibrous web which comprises the steps of continuously carding fibers on a rotatable carding surface and transferring said carded fibers directly from said rotatable carding surface -to projections lying in a rotatable surface having a much lower peripheral surface linear speed than that of said rotatable carding surface to form a carded fibrous web on said rotatable surface, said carded fibrous Web having a predominant direction of fiber orientation along the longitudinal axis thereof, the improvement which comprises: transferring said carded fibrous web directly from said rotatable surface to projections lying in a second rotatable surface closely adjacent -to but spaced from said first-mentioned rotatable surface by a clearance of from about 0.005 inch to about 0.17-5 inch, said second rotatable surface moving in the same direction as said first-mentioned rotatable surface at the point of closest adjacency and having a peripheral surface linear velocityv less than about 45% of the peripheral surface linear velocity of said first-mentioned rotatable surface to condense the fibrous web on the second rotatable surface so that it has at least about 2% times the weight it had on the first-mentioned rotatable surface but has increased cross strength, enhanced drafting character- `istics, and substantially no predominant direction of fiber orientation; and transferring said fibrous web to a third rotatable surface closely adjacent to but spaced from said second rotatable surface and having a peripheral surface linear velocity greater than and up to about five times the peripheral surface linear velocity of said second rotatable surface.

S. In a method of improving the cross strength and drafting characteristics of a fibrous web which comprises the steps of continuously carding fibers on a rotatable carding surface and transferring said carded fibers directly from said rotatable carding surface to projections lying in a rotatable surface having a much lower peripheral surface linear speed than that of said rotatable carding surface to form a carded fibrous web on said rotatable surface, said carded fibrous web having a predominant` direction of fiber orientation along the longitudinal axis thereof, the improvement which comprises: transferring said carded fibrous web directly from said rotatable surface to projections lying in a second rotatable surface closely adjacent to but spaced from said first-mentioned rotatable surface by a clearance of from about 0.005 inch to about 0.175 inch, said second-rotatable surface moving in the same direction as said first-mentioned rotatable surface at the point of closest adjacency and having a peripheral surface linear velocity less than about 45% of the peripheral surface linear velocity of said firstmentioned rotatable surface to condense the fibrous web 0n the second rotatable surface so that it has at least about 2%, times the weight it had on the first-mentioned rotatable surface but has increased cross strength, enhanced drafting characteristics, and substantially no predominant direction of fiber orientation; and transferring said fibrous web to a third rotatable surface closely adjacent to but spaced from said second rotatable surface and having a peripheral surface linear velocity at least equal to the peripheral surface linear velocity of said firstmentioned rotatable surface.

6. In a method of improving the cross strength and drafting characteristics of a fibrous web which comprises the steps of continuously carding fibers on a rotatable carding surface and transferring said carded fibers directly from said rotatable carding surface to projections lying in a rotatable surface having a much lower peripheral surface linear speed than that of said rotatable carding surface to form a carded fibrous web on said rotatable surface, said carded fibrous Web having a predominant direction of fiber orientation along the longitudinal axis,` thereof, the improvement which comprises: transferring said carded fibrous web directly from said rotatable surface to projections lying in a second rotatable surface closely adjacent to but spaced from said first-mentioned rotatable surface by a clearance of from about 0.005 inch to about 0.175 inch, said second-rotatable surface moving in the same direction as said first-mentioned rotatable surface at the point of closest adjacency and having a peripheral surface linear velocity less than about 45% of the peripheral surface linear velocity of said first-mentioned rotatable surface to condense the fibrous web on the second rotatable surface so that it has at least about 21A times the weight it had on the first-mentioned rotatable surface but has increased cross strength, enhanced drafting characteristics, and substantially no predominant direction of fiber orientation; and transferring said fibrous web to a third rotatable surface closely adjacent to but spaced from said second rotatable surface and having a peripheral surface linear velocity greater than the peripheral surface linear velocity of said first-mentioned rotatable surface.

7. In a method asdened in claim 1, the improvement wherein the second rotatable surface has a peripheral surface linear velocity of less than about 45% down to about 4% of the peripheral surface linear velocity of the first 10 mentioned rotatable surface to increase the weight of the web on the second rotatable surface by a multiple of from about 2% times up to about 25 times its weight on the first mentioned rotatable surface.

8. In a method as defined in claim 1, the improvement wherein the second rotatable surface has a peripheral surface linear velocity of less than about 45% down to about 1% of the peripheral surface linear velocity of the first mentioned rotatable surface to increase the weight of the web on the second rotatable surface by a multiple ofV from about 2% times up to about 100 times its weight on the irst mentioned rotatable surface.

References Cited by the Examiner UNITED STATES PATENTS 46,120 1/1865 Lord et al. 19-106 166,578 `8/1875 Woodbury 19--106 206,510 7/1878 Whitcomb et al. 19--106 2,409,898 10/ 1946 Ramsdell 19-155 2,774,112 12/ 1956 Hopkinson 19-106 v3,081,499 3/1963 Goldman 19-99 FOREIGN PATENTS 1,144 of 1860 Great Britain.

2,716 of 1857 Great Britain.

3,168 of 1869 Great Britain.

ROBERT R. MACKEY, Primary Examiner.

20 DONALD W. PARKER,`Examner.

Claims

1. IN A METHOD OF IMPROVING THE CROSS STRENGTH AND DRAFTING CHARACTERISTICS OF A FIBROUS WEB WHICH COMPRISES THE STEPSS OF CONTINOUSLY CARDINGFIBERS ON A ROTATABLE CARDING SURFACE AND TRANSFERRING SAID CARDED FIBERS DIRECTLY FROM SAID ROTATABLE CARDING SURFACE TO PROJECTIONS LYING IN A ROTATABLE SURFACE HAVING A MUCH LOWER PERIPHERAL SURFACE LINEAR SPEED THAN THAT OF SAID ROTATABLE CARFING SURFACE TO FORM A CARDED FIBROUS WEB ON SAID ROTATABLE SURFACE, SAID CARDED FIBROUS WEB HAVING A PREDOMINANT