US2434887A - Method of cross laying - Google Patents

Description

Jan. 20, 1948. G. E. REPASS ET AL METHOD OF CROSS LAYING 2 Sheets-Sheet 1 Filed June 14, 1946 Jam 2% 394%; a. E. REPASS ET AL I 2,43%83? METHOD OF CROSS LAYING Filed June 1.4, 1946 I 2 Sheets-Sheet 2 OFFICE METHOD OF CROSS LAYING George E. Bcpass and James E. Bepass, Hopedale, Mass.

Application Jnne 14, 1946, Serial No. 676,824

1 'This invention relates to improved sheet materials and toe. method of forming a web of fibrous sheet material in which a plurality of layers of fibers are arranged upon one another with the fibers in at least one of the layers extending angularly with respect to the fibers of the remaining layers. When fibers, for example in the form of cotton slivers, are passed through drawing rolls,- there is obtained a thin web of sheeting material which may be quickly and cheaply produced. Eiforts have been made to utilize this cheap-material in various ways and especially as a retaining web for carrying impregnating bodies such as adhesives and the like. These attempts have not been entirely successful, due in part to lack of strength in the web. Such weakness makes it difiicult to handle the material before or during impregnation, while the impregnated productoftentimes does not have as great resistance to stretch and breaking as may be desired for some purposes. e

I 9 Claims. (01. 19-161) creasing the strength characteristics of such materials, while at the same time preserving to a much greater extent uniformity of thickness and smooth appearance. It-is' further an object of the invention to improve methods of combining cross lengths of fiber with other layers of fibers I andto avoid objectionable variation in thickness Then too there frequently arises a requirement that the retaining web which is to be impregnated present a relatively uniform thickness and appearance. Here another problem is encountered, owing to the fact that the drawing operation as commonly practiced, by its very nature tends to draw fibers in aweb to a greater extent at some points than at others, and hence there are frequently produced relatively thick and thin areas in the web of irregular and unsi htly appearance.

Attempts have been made alo g several lines to increase the strength of such webs. Thus the use of a plurality of layers to form a laminated body has been tried with some successand in this connection it has been suggested that one or more layers be so arranged that fibers'of adjacent layers extend angularly across one another in order that the composite web may present greater strength in two dimensions. v

In resorting to the use of cross lengths of drawn fiber, however, there is an increase in irregularity and non-uniformity of thickness of the composite web especially where adjacent sections of crosslaid layers of fibers are arranged in overlapping relation. The overlapping portions tends to produce an unsightly ridge or double thickness. For

some purposes this variation in thickness is quitenoticeable, affecting the sale of the product andbecoming especially troublesome in the impregnated -product.

An object of the invention is to deal with the v problems outlined, and to improve methods of forming cheap multilayer webs with a view to inresulting from applying the cross lengths in overlapping relation to one another.

. We have found that greatly improved results both in respect to strength characteristics and appearance, may be obtained by employing specific drawing and handling operations. An important feature of the invention therefore is a method of laminating a plurality of layers of fiber. immediately after the webs have been subjected to a drawing operation so that fibers of the respective webs, in seeking to return from a'somewhat straightened out position to a normally curled state, may become interlocked with one another, thus tending to induce integration of the adjacent layers and provide greater strength.

Another important aspect of the invention is a method of drawing the cross lengths in a more selective manner to produce relatively thin feathered edges, and then arranging the feathered edges of adjacent cross lengths in exact overlapping relation so as to provide a continuous layer of cross lengths at no point in which the thickness exceeds the maximum thickness of any one of the cross lengths.

Still another feature of the invention is a method of combining overlapping cross lengths of fiber with top and bottom webs of fibers in which the cross lengths are separated by the drawing rolls so as to present relatively thin broken ends. The

thin broken ends are clipped and arranged between relatively thicker side edges of the top and bottom webs to insure uniformity of thickness and appearance at these points also. Other objects and novel features will appear from the following description of the invention.

The accompanying drawings illustrate a preferred embodiment of the method oftion, in which Fig. 1 is a perspective view illustrating apparatus utilized to carry out web-forming operations from cotton fiber;

Fig. 2 is a fragmentary plan view of a single web of drawn fiber;

Fig. 3 is a cross section taken on the line 33 of Fig. 2;

Fig. 4 is a diagrammatic view further illustrating web-forming operations;

the inven- Fig. 9 is anotherfragnieritary plan view illus-.

trating a plurality of layers of iibers mounted one upon another;

Fig. 10 is a diagrammatic perspective view 11- lustrating cutting operations;

Fig. 11 is another plan view; and

Fig. 12 is a cross section taken on the line l2l2 of Fig. 11.

The method of the invention generally includes the lanunatmg or building up of a plurality of layers OI. freshly drawn fiber. A principal example of raw StOCK iS cotton SllVEIS. The'invention is particularly directed to treating this material and is for the sake of convenience described with reference especially to handling cotton fiber although it is not intended that the invention be limited to this particular material.

The several layers of fiber are delivered from separate drawing roll units and are rapidly brought into contact-with one another at a point just after the drawing operations have taken place, and at a time when the constituent fibers of each of the webs are in a relatively straightened out position from which they have some tendency to recoil upon themselves into a normal curled formation. By bringing the fibers of ad'- jacent layers into contact with one another at the precise point noted, they are given an opportunity to interlock with one another and yet are prevented from losing all of their straightened 15011113161011. Such an effect is further developed by imparting a firm pressure to the composite web by means of a calendering step.

To secure as much attenuation or straightening of the fibers as possible, we find that it is preferable to subject the cotton slivers to a preliminary drawing operation, using conventional type drawing rolls and winding the roughly drawn stock upon a drum. Then a plurality of webs thus obtained are again drawn and almost instantly thereafter are brought together and calendered.

In a preferred form of the invention three layers of drawn fiber are utilized although it is intended that a greater number of layers may be employed in some cases. A bottom layer is first drawn and disposed upon a moving conveyor belt which carries the web along to a point where it receives an intermediate layer made up of a plurality of cross lengths arranged transversely of the bottom layer in overlapping relation.

Carefully controlled drawing is employed in forming the cross lengths to provide a selective application of pressure and thus obtain gradually feathered thin edges at opposite sides of each cross length. The feathered edges are The bottom layer carrying the overlapping cross lengths of fibers is carried along by the 0011- veyor belt to a further point at which a top layer of freshlydrawn fiber is applied. Thereafterthe composite web is acted upon by shearing mechanism which clips the broken ends of the cross lengths just prior to the web passing through the calender rolls. From the calender rolls the web is wound upon itself on a drum in readiness for impregnatingoperations. j I

Withthis general description in mind, the process may be considered in reater detail and attention is directed to" Fig. l in which is illustrated a table or frame I at the opposite side of which is mounted a. conveyor belt 2, movingin the direction indicated by the arrow. Arranged above the conveyor belt in some convenient manner, as by adjustable suspension frames or brackets of conventional character, are three rolls of drawn cotton fiber 3, 4 and 5.

Drawn fiber is taken from the roll 5 and passed through a set of drawing rolls 6, which may be of the well known construction. From the drawing rolls 6, a web I is obtained which drops down upon the belt 2 and is moved toward the next roll. The web I as it comes from the drawing rolls 6 normally presents a substantially uniform cross sectional thickness along most of its extent. At its extreme edges, however, there is a tendency for the fibers to be disengaged and fray, thus leaving at some points thin irregular portions 8 and 9 indicated diagrammatically in Fig, 2.

In accordance with the invention, we subject the web to a slight compacting step carried out by passing the web 1 through curved guides I0 and H (see Fig. 2) which pack the loose fibers and tend to increase slightly the thickness of the web along the edge portions l2 and I3. The purpose of these relatively thick edges will be explained at a later point.

The roll 4 is arranged preferably with its axis extending at right angles to the axis of the roll 5. Material is taken from this roll and passed through drawin rolls l4 to produce a length N3 of fiber having forward free ends i6. These free ends of the cross length l5 are so positioned that they extend well beyond the edge of web I. The roll 4 and drawing rolls M are preferably supported in an adjustable member by means ofwhich the cross length i5 is laid across the web I in a right-angularly disposed manner. When a suflicient amount of drawn material has been delivered to extend across the web I, the drawing rolls break the material to separate the length 15 from the remainder of the web on roll 4. The break is timed so that there are formed projecting ends l8 which also extend well beyond the opposite side edge of the underlying Web, 'The caused to constitute an appreciable part of the cross lengths are united to form an intermediate layer denoted by numeral 2 I. I,

An important feature of this last drawing operation is a selective application of l the material coming from the roll 4 solth the central portion of the cross len'git formed with a normal thickness e tions are radually tapered out t ressure" to amass? tively thin feathered edges I! and II suchk are diagrammatically shown in Figs. and 6. we

have found that by suitably controlling the application of pressure to the top roll of set of-drawing rolls, for example by tightening conventional tension springs employed in su devices especially in' the case of relatively ion drawing rolls. we are enabled to secure a gradual feathering such as shown, and these feathered edges maybe caused to extend throughout a substantial portion of the width of a cross length of material.

'An exceedingly desirable improvement is derived from the feathered edges in connection with some points, which produced an unsightly seamlike or rigid appearance, materially detracting from the value of the product.

The relatively large feathered areas of the cross lengths of the invention on the contrary provide a marginal area in which such irregularlties are taken care of and the edges of two adjacent cross lengths complement one another so that almost all trace of the ridged effect is eliminated. By this means there is made available a rapid and accurate method of employing cross lengths of drawn fiber with all the advantages of two dimensional strength and without a faulty appearance. It should be observed also that a cross sectional thickness may thus be obtained which is substantially uniform throughout all points of the intermediate layer 2i and which corresponds to the maximum thickness of any one of the cross lengths.

The overlapping cross lengths thus assembled together with the bottom web I. next pass under a the roll 3 from which is taken again a freshly drawn web 22 delivered by drawing rolls 23. This web is carefully positioned so that its edges coincide as closely as possible with the edges of the bottom web I, thus leaving the broken ends of the cross lengths l5 projecting outwardly from either side. Preferably the edges of the top web 22 are compacted in the same manner as described in connection with web I. to form relatively thick portions.

. It will readily be seen that in breaking the cross lengths with the drawing-rolls in the manner described above, there will necessarily result thinned areas adjacent the brokenends and these thinned areas again may be-sufliciently pronounced so that a non-uniform appearance will result. For this reason we' have-provided the compacted edges of both the bottom and top webs 1 and 22 with their relatively thicker areas. These relativelythicker areas although extending transversely with respect to the thinned broken ends of the cross lengths, nevertheless produce a bodying effect which tends to maintain the thickness of-the composite web more nearly uniform along the side edges and thus produces a more pleasing appearance.

As soon as the top layer is applied, the comperformed by shears 24 and as which may be arranged in some suitable manner along the sides of the conveyor belt. The shears clip the straggling ends of the cross lengths along lines passing parallel and closely adiacent to the thickened edges of the top and bottom webs. to provide a uniformly trimmed edge as shown mm. 10. Thereafter the web is subjected to a light pressure such as is exerted by a' calender roll indicated at the left-hand side of Fig. 1, and the finished stock is then rolled up on a drum.

The method of the invention and the specific drawing operations described may be modified in various respects as for example in connection with making a web composed of a larger number of layers or in arranging the cross lengths in different positions and in various other respects. Similarly, it should be understood that the procedures outlined for handling fibrous material is not limited to cotton slivers, but may be practiced in respect tovarious other fibers, both natural and synthetic, and likewise the mechanical means for producing the results noted may be altered, and other structures employed.

From the foregoing description, it will be seen that we have provided a method of handling thin webs of drawn fiberto produce acomposite web in which increased strength is derived from bringing to'gether a plurality of layers immediately upon being delivered from drawing roll units. As a result of this, improved interlocking of adjacent fibers is carried out.

Further strength features are developed from having fibers of at least one layer running angularly with respect to the fibers of other layers, thus to provide resistance to stretching and breaking in two dimensions. In achieving these improved strength characteristics in the com-.

posite web, we have also been able to avoid to a'large extent the occurrence of relatively thick and thinareas which normally tend to produce an irregular and unsightly appearance. Especially along the side edges of the composite web and at points of overlapping of cross lengths,'

we have provided compensating factors which function to maintain a relatively uniform thickness at all points. It will be observed that the operations tending to bring about these beneficial results are subject to relatively high speed operation and thus further adapt themselves to rapid and cheap manufacture of a drawn fiber web, while suited to impregnating operations.

We claim:

1. Method of forming a multi-layer cross-laid fibrous web which includes drawing a web of fibrous material and applying relatively greater pressure to the side portions thereof so as to cause the sheeting to be drawn to a greater extent along its edges than at'adjacent midportions and thus form feathered edges; laying a plurality of lengths of the said feathered sheeting on a base web of drawn fibrous material with the feathered edges of adjacent cross lengths lying in overlapjfibrousmaterial in which a layer made up of ping relation and being so arranged as to present a cross-sectional thickness throughout points of overlap substantially corresponding to the thicknessof a midportion of any one of said cross lengths; and then laying a top layer of drawn fiber upon the overlapping cross lengths.

2. In a method of'forming a multilayer web of cross lengths of drawn fiber is'interposed between top and bottom layers of drawnfiber, the step which comprises forming the cross lengths with posite web is subjected to a shearing operation thin feathered edges and arranging the feathered edges of adjacent cross lengths upon one another so as to complement one another and provide a pniform thickness at all points of overlap.

3. Method of formin a multilayer web which comprises drawing fibrous material to form a bottom web, passing the edges of the bottom web through guides to compact these edges and produce relatively thick edge portions; drawing a second web of fibrous material so as to provide relatively thin feathered edges and relatively thicker intermediate portions; separating the second web into a plurality of cross lengths and laying the cross lengths transversely of the said bottom web, with the said feathered edges of adjacent cross lengths disposed in overlapping relation to prfsent an intermediate layer of fiber of substantial y uniform thickness; then drawing a third web of fiber with relatively thick compacted edge portions and laying it upon the said cross lengths.

4. Method of forming a fibrous web which comprises drawing a fibrous material to form a bottom web having relatively thick edge portions; drawing a second web of fibrous material so as to form relatively thin feathered edges and relatively thicker intermediate portions; separating the second web into a plurality of cross lengths and arranging them transversely of the said first web with free ends of fibers in the cross lengths extending beyond the said edges of the bottom web;

said feathered edges being disposed in overlapping relation to present an intermediate-layer of fiber of substantially uniform thickness at all points therealong, drawing a third web of fiber with relatively thick edge portions and laying it upon said cross lengths with its edges coinciding with the edges of the bottom web; and then cutting the said free ends of the cross lengths along lines passing parallel with and closely adjacent to the opposite edges of the said bottom and top webs of fiber.

5. Method of forming a composite fibrous web which comprises drawing cotton fiber to form a bottom web; compacting the edges of the web as it is passed along a conveyor member; drawing cotton fiber to form a web having relatively thin feathered edges; applying transversely of the bottom web a section of the feathered stock and separating the feathered stock to provide broken ends which extend beyond the sides of the bottom web; applying, transversely of the bottom layer, additional sections of separated feathered stock with adjacent feathered edges of said additional lengths occurring in overlapping relation to'provide a cross-sectional thickness at points of overlap of substantially the same thickness as inter- .mediate portions of a cross length; drawing a top web of fiber with compacted edges; laying the top layer of fiber over the overlapping cross lengths; and cutting those portions of the broken endsof the cross lengths which extend beyond the compacted edges of the said upper and lower webs.

6. In a method of forming a multilayer web of fibrous material in which an intermediate layer made up of cross lengths of drawn fiber is'combined with other layers of drawn fiber, the step which comprises forming the cross lengths with thin feathered edges and overlapping the feathered edges of adjacent cross lengths to complecurled position; said web having the feathered edge portions separated into cross lengths applied transversely of the web with feathered edges of adjacent cross lengths occurring inoverlapping relation, and then applying pressure to cause interlocking of fibers of respective webs.

8. Method of forming a fibrous web which comprises: drawing a web of fibers and thinning the opposite edges of the web; dividing the web transversely into a plurality of lengths of web forming material; and superimposing thinned edges of said lengths one upon another to form a continuous long web of uniform thickness whose fibers extend generally transversely of the long dimension of the web.

9. Method of forming a long cross-laid web of fibrous material which comprises: drawing a first long web of fibers; drawing a second, thin-edged web of fibers; dividing the second named web transversely into shorter lengths of web; and

placing said shorter lengths in edge-overlapped relation transversely upon said first web to produoe a long cross-laid web of uniform thickness in its length. I

, GEORGE E. REPASS.

JAMES E. REPASS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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