US 3749138 A
Description (OCR text may contain errors)
ABSTRACT 1 1 THICK FABRICS Fabrics in accordance with the invention are characterized by densely woven bodies of substantial thickness,
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substantially concentric or spiral fashion within the cylinder.
Primary Examinerl-1enry S. Jaudon AttorneyFraser and Bogucki 7 Claims, 5 Drawing Figures Patented July 31, 1973 3 Sheets-Sheet 1 INVENTORS WALTER A. RHEAUHE BY ARTHUR R. CAIIP'MN F tmaml A TTORNEYS Patented July 31, 1973 3 Sheets-Sheet 2 uvvsurons WALTER A. RHEAUME BY ARTHUR R. CANPIMN ATTORNEYS Patented July 31, 1973 3 Sheets-Sheet INVENTORS WALTER A. RHEAUME BY ARTHUR R. CAHPNAN ATTORNEYS THICK FABRICS BACKGROUND OF THE INVENTION l. Field of the Invention This invention relates to thick woven fabric structures, and more particularly to such structures, as related to thick walled, high strength fabric shapes of complex configurations.
2. Description of the Prior Art Many modern applications for fiber reinforced structural components demand particular characteristics substantially superior to those heretofore attainable by conventional techniques, such as filament winding or multiple layer laminates, or other comparable processes. Accordingly, there have previously been devised, as evidenced by U.S. Pat. No. 2,998,030, methods for making complex shapes in the form of bodies of revolution. In accordance with such methods curvilinear fabrics may be woven to conform with a relatively high degree of accuracy to a predetermined form, such as a cone shape. A number of such fabric constructions may be stacked to provide a thick walled laminated body having substantial structural advantages over other constructions, because of high strength and freedom from irregularities.
As stringent performance rquirements are imposed on such structures, however, it is found to be preferable to avoid laminations completely if possible. The problem of inadequate interlaminar shear strength is minimized if no distinctly laminated structure exists. Under exposure to high velocity and high temperature gases, for example, the outer portion of the structure is eroded and substantial interlaminar stresses are introduced. These factors in combination often result in severe damage to a structural system.
Independently ofa need for thick walled hollow 'bodies, there exists a need for thick walled fabrics having a regular fiber pattern that is extremely dense and has high strength in all directions. Somewhat thick fabrics have been employed in a number of different constructions, as in flexible conveyor belting, tires, drive belts and the like. Prior art constructions generally dispose the fibers in a maximum of three or four separate layers which are interwoven only to a limited degree. The weaving patterns moreover are essentially loose and open, with the woven fibers serving only as a central reinforcement for the principal matrix material, such as rubber or neoprene. Various workers in the art have suggested using weaves in which warp yarns zigzag between alternate broad faces of a fabric, as evidenced by U.S. Pat. No. 1,335,311 to Zeglen. The fabrics disclosed in this and related patents relate only to loosely woven fabrics, which are only small fractions of an inch in thickness and have only a few plies. It is known, as in the manufacture of tires, to make a thick body by using relatively few plies loosely woven within a matrix such as rubber. It is now desirable however, to form predominantly filamentary woven bodies having thicknesses of approximately one-half inch or more, and high fiber densities together with the non-laminar structural and omnidirectional strength characteristics previously mentioned.
Such thick fabrics have not heretofore been suggested or achieved, nor have any machines or methods for weaving such fabrics been suggested or achieved. The combination of such fabric characteristics in solid cylindrical shapes or in thick walled bodies of revolution of substantially continuous form presents even more severe problems. The various aspects of the present invention solve such problems in a manner whice permits relatively fragile high temperature fibers to be densely woven into thick walled bodies of selected shapes.
SUMMARY OF THE INVENTION Fabrics in accordance with the invention comprise thick walled surfaces or bodies which have a high proportion of filamentary material and are extremely dense and substantially homogeneous in that they are free of internal laminations or layers. Such woven bodies may have in excess of approximately warp ends per inch and 200 picks per inch, depending upon yarn size and fabric thickness, and a density in excess of about 20 percent of the density of the filamentary material from which it is woven. The warp yarns traverse a substantial part of the thickness of the fabric, along successively angled paths, with the fill yarns being disposed perpendicularly to the warp yarn planes in the interstices between the warp yarns. Longitudinal stuffer yarns may also be disposed within the body, parallel to the warp yarn planes but perpendicular to the fill yarns. Products in accordance with the invention also comprise solid cylindrical and hollow thick walled bodies of revolution such as cones and frustums substantially free of radial and circumferential discontinuities. In such products, the warp yarns lie along radially disposed planes relative to the central axis of the body. Varying diameters, in the case of a frustum, are provided by adding further warp yarn planes as the diameter of the frustum increases. In the solid cylindrical body the warp yarn planes are of varying length inwardly from the outer surface to provide a completely interwoven body of substantially uniform density throughout its interior.
BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of the invention may be had by reference to the following description, taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a sectional view of a portion of a thick walled fabric in accordance with the invention, viewing the warp yarn planes from the side;
FIG. 2 is an end sectional view of the fabric of FIG.
FIG. 3 is a perspective view, partially broken away, of a thick walled frustum in accordance with the invention;
FIG. 4 is a perspective view, partially broken away, of a portion of a solid cylindrical fabric in accordance with the invention; and
FIG. 5 is a perspective enlarged view of a fragment of the fabric of FIG. 4 showing the yarn relationships therein.
DETAILED DESCRIPTION OF THE INVENTION Machines and methods in accordance with the invention provide products with improved uniformity because of the absence of folds, edges and seams and because of the uniform fill yarn tension achieved with a continuously operating circular shuttle. The disposition of a plurality of Jacquard heads around the circular loom makes available an adequate number of warp yarns for thick, dense and large woven structures. Virtually continuous operation insures useful production rates.
Reciprocating shuttle systems cannot of course provide a part having the configuration of a closed loop, although a reciprocating shuttle system using Jacquard head control would be employed for weaving most flat fabrics. It will be appreciated, however, that continuous circular weaving of a circular part can result in an arc length which is essentially flat for a given distance if the diameter is great enough. Segments of such a product may be employed for applications in which a flat thick fabric is needed, if desired.
The method of weaving described herein has been directed to the preparation of woven fabric parts having the form of a body of revolution, specifically conical and frustum shapes. A great variety of other hollow shapes and solid shapes can however be woven. By the use of different mandrel and guide configurations, specialized forms such as ellipsoids, hyperboloids and elliptic paraboloids and rectangular or squareapproximating shapes can be woven. Nonsymmetrical shapes such as frustums having flat surfaces can also be woven by appropriate shaping of the mandrel segments.
Methods of weaving hollow bodies and solid cylindrical forms in accordance with the invention are both characterized by the establishment of warp yarn planes which lie along radial planes relative to the central axis of the part. In weaving a thick walled hollow body, the warp yarns traverse between the interior and exterior sides of the fabric along angled paths. Adequate interlocking is achieved if such warp yarns traverse a major part of the thickness, and they need not traverse the entire thickness although this is preferred. In weaving a part of varying diameter, new warp yarns are progressively added as the diameter increases, effectively inserting additional warp yarn planes to maintain the density of the material essentially constant. The same general characteristics are true of the warp yarns and fill yarns in a solid cylindrical member, but in this instance, the successive individual warp yarn layers have different and progressively varying inward lenghts from the outer surface of the part.
Thick fabric parts in accordance with the invention incorporate substantial interlock of warp and fill yarns through a plurality of fill yarn layers.
As shown in FIG. 1, warp yarns 82 pass in successively alternating diagonal paths between one side of the fabric and the other. A specific example of a flat fabric part is illustrated in FIGS. 1 and 2, such as may be provided by a reciprocating shuttle system. A circular loom system satisfies much more difficult criteria, but the thick fabrics produced by reciprocating shuttle and circular shuttle systems have a number of common aspects in accordance with the invention. As illustrated generally in FIG. 1, although this is not intended to be a pictorial depiction of the cross-sectional view, multiple warp yarns 82 following progressively displaced zigzag patterns define separate interstices within each region in which segments of four different yarns are adjacent. The fill yarns 51, perpendicular to the planes of the warp yarns 82, pass through the interstices to provide an extremely dense as well as thick part which is essentially homogeneous and non-laminar in nature. Any number of a variety of yarns may be utilized, including natural and synthetic fibers.
The above example relates to a heat and ablation resistant product, such as a rocket nozzle or heat shield, and the specific fibers discussed are graphite. For high temperature applications similar refractory fibers including carbon, silica, quartz or glass may be employed. Although the fill yarn 51 is essentially continuous so that it can be interchanged, on an economic basis, only at relatively long intervals, the warp yarns 82 can be intermixed in virtually completely arbitrary fashion, for specific strength and temperature properties. It is preferred for most applications to improve resistance to abrasion and permit the use of greater tension during weaving by modifying or treating the particular yarn. Thus in the specific example referred to above, the graphite yarn incorporates a nylon serving for better strength and abrasion-resistant properties. Separately or in combination, a sizing or coating may be applied to the yarn for like purposes. It is very'often found useful to employ a Teflon coating because of the low friction characteristics imparted to the yarn.
As further shown in FIG. 1, longitudinal stuffer yarns 97 may be disposed parallel to the plane of the warp yarns and perpendicular to the fill yarns. The stuffer yarns 97 not only serve to increase the density of the fabric, but additionally increase the strength of the fabric along the axis to which they are parallel. The longitudinal stuffer yarns 97 each lie in a different leven level are fed in during the weaving.
Viewed in the idealized section of FIG. 8, along the planes of the warp yarns, it will be seen that the fill yarn 51 alternates between successive levels. Those skilled in the art will recognize, however, that the fill yarns can also be interwoven between the different levels so as to achieve a further interlocking effect.
Fabric parts in the flat form of FIGS. 1 and 2, and in the form of hollow or solid bodies as described hereafter, have the dual characteristics of substantial thickness and high density in the uncompressed, as-woven form. The internal pores and interstices typically are filled by an impregnating resin or other matrix, and the part is rigidified and densified by high temperature curing under pressure. The density of the filamentary components of the as-woven part is extremely important, however, because of thecontribution imparted, in terms of physical properties and temperature resistance, to a composite part by the filamentary components. Densification by conventional techniques compacts or densifies the fabric itself only to a certain limited degree, and consequently high density in the aswoven form is critical.
Fabrics in accordance with the invention have densities, in the as-woven form of in excess of about 20 percent of the density of the material from which the fabric is woven, as well as substantial thickness. In practice, substantially higher densities have been achieved, as indicated below, but many different considerations govern the ultimate nature of a specific fabric. Total thickness, for example, decreases as yarn diameter decreases, whereas density increases. In weaving a flat part with a yarn of 0.025 inch diameter, approximately 300 picks per inch and 144 warp ends per inch, a fabric of approximately 1/2 inch thickness is provided. Under comparable conditions a 0.010 inch yarn provides a part approximately one-fourth inch thick, whereas a 0.040 inch diameter yarn yields a part approximately three-fourth inch thick. To achieve even thicker fabrics, recognition must be given to the fact that the number of ends that can be handled in a reciprocating shuttle loom are substantially greater. Thus to make an even thicker part, the number of heads, the number of levels, and the number of ends and picks per inch are increased along with the use of heavier yarns.
The closeness of the weave may also be viewed in terms of the percentage of fabric volume occupied by filamentary material, a figure which also varies with many factors, including the type of yarn, the ends and picks per inch, and the nature of the weave. Thick fabrics in accordance with the invention have filamentary constituents occupying in excess of about 20 percent of total volume, although as noted below, substantially higher values have been achieved.
In general, inclusion of stuffer yarns without reduction in the number of warp ends per inch substantially improves properties in determinable respects. Generally, properties are generally lowest in the warp yarn direction, but such properties may be materially enhanced to insure that the fabric body has substantial structural integrity in each of three mutually orthogonal directions, so that it may be regarded as omnidirectional in character. For example, a thick quartz fabric in a phenolic resin system using stuffer yarns, as'opposed to a non-stuffer yarn weave, had warp direction tensile strength'of 21,300 psi vs 4,600 psi, warp direction compressive strength of 27,000 psi vs 13,100 psi, and flexural strength of 43,500 psi vs 10,700 psi, plus substantial increases in modulus of elasticity.
Smaller yarns may of course be twisted or bunched to increase the effective diameterfor weaving. Utilizing such techniques together with a 24-leve1 weave with 300 picks per inch and approximately 230 ends per inch, fabrics approximately 1 1/4 inches in thickness have been woven.
Circular looms can be employed to permit substantial increases in the number of ends, such as 500 ends per inch, and thicknesses can be correspondingly increased. Although circular looms are not limited in the same way as a reciprocating shuttle system with respect to the number of ends per head, a limiting factor is encountered in terms of abrasion between yarns and between various parts of the mechanism. Use of finishes or serving assits substantially in minimizing inter-yarn abrasion. To prevent the lingos from rubbing together, separate comber boards used as expanders and contractors are of particular benefit. In addition, the use of wire type heddles limits contact between these particular elements.
As previously noted, the yarns are highly interlocked between different levels, and therefore terms such as ply" or layer are misdescriptive in denoting the extent of thickness. It is more appropriate to refer to fill yarn levels, because even where the weave is such that the fill yarn itself is used for inter-level interlock different levels can nonetheless be discerned. At least four levels are used, although in general 12-16 levels are employed in a flat fabric, using approximately 14 yarns per level.
Fabrics in accordance with the invention have a number of significant characteristics. For the first time densely woven yarns in a thick body may be so arranged as to provide a highly interwoven, essentially homogeneous construction. Using multiple fill yarn levels and angled warp yarns in multiple planes substantially normal to the face or faces of the fabric, the resulting body has a non-laminar character having substantially maximum resistance to delamination and inter-laminar shear problems under extreme conditions.
The figures given for the density of the filamentary constituents in the as-woven fabrics is the bulk density for the particular material used as the yarn. The density of pure quartz, for example, is approximately 137 lbs/ft and woven parts in accordance with the invention have densities in excess of about 20 percent of this figure despite the inherent porosity of the filaments and the yarn. The fabric density value is generally in excess of about 25 percent of the yarn material density when the fabric incorporates full angle interlock in the warp yarns e.g., when each warp yam traverses a zigzag path from one broad face of the fabrics to the other.
Using various yarns in different weaves, a variety of fabrics in accordance with the invention have provided unique strengths and densities. Although the physical properties of a given fabric will not be uniform in all directions, the fabric can be said to have omnidirectional properties in that no significant weakness exists in any direction. The-following specific examples of fabrics all relate for ease of comparison to flat fabrics:
EXAMPLE I A carbon 3 end VYB 1/2 type yarn with nylon serving was woven with a warp count of 168 ends per inch and a fill count of 256 picks per inch to give a fabric 0.740 inch thick with a density of 37.49 lbs/ft. The fabric density was 32.6percent of the density of carbon and the filamentary constituents were 30,9 percent of theoretical volume.
EXAMPLE 11 A quartz fabric of 0.530 inch thickness was woven of 3 end 300/4/4 warp yarn and 300 2/6/4 fill yarn, with a warp count of 144 ends per inch and a fill count of 300 picks per inch, to give a density of 76.8 lbs/ft. This fabric had a density equal to 56.0 percent of the density of quartz and 66.4 percent of theoretical volume. An I 1 end 300/2/2 nylon served quartz yarn with ends per inch and 200 picks per inch was by contrast woven to give a fabric 0.740 inch thick, with 35.63 lbs/ft density.
EXAMPLE 111 An 0.660 inch thick fabric of nylon yarn of 840 denier, 6 ply type was woven with a warp count of 144 ends per inch and a fill count of 282 picks per inch to have a density of 42.09 lbs/ft. This fabric had 59.2 percent of the density of nylon and 54.9 percent of theoretical volume. In contrast, the same yarn type woven with 72 ends per inch and 72 picksper inch resulted in a fabric having a density of 31.38 lbs/ft", 44.2 percent of the density of nylon and 46.1 percent of the theoretical volume.
EXAMPE IV A 0.585 inch thick fabric was woven of E glass fibers, using 4/2 3 ply yarn, a warp count of 144 ends per inch and a fill count of 300 picks per inch. This fabric had a density of 76 lbs/ft, which is 48.1 percent of the density of E glass. The filamentary constituent occupied 42.8 percent of theoretical volume.
EXAMPLE V A 0.730 inch thick fabric of 1,650 denier 4 ply rayon yarn was woven with a warp count of 144 ends per inch and a fill count Of 240 picks per inch, to give a density of 47.61 lbs/ft This fabric was 50.6 percent of the density of rayon and 55.96 percent of theoretical volume.
A thick walled body of revolution, is illustrated in FIG. 3 shows broadly the relative disposition of the warp yarns 82, the fill yarns 51 and the stuffer yarns 97. This essentially continuous structure has new warp end planes added into the body along its length in accordance with increased diameter. Thus the density of the filamentary components remains high and essentially constant throughout a non-uniform part. The new warp ends are so interlocked in the remainder of the structure that the entire produce is a single piece of essentially continuous construction requiring only a minor amount of trimming, followed by impregnation, molding including curing, and final machining.
A solid cylindrical body 100 in accordance with the invention is shown in FIGS. 4 and 5. A central core 102 of small diameter is disposed concentric with the central axis to provide a solid interior portion about which the fill yarn may be wrapped.
ln FIG. 4, the warp yarns are seen to lie in planes radial to the central axis of the cylinder 100, about the small central core 102. Successive warp yarn planes A, B, C, D, E, F, G, H are shown in broken away section, to represent one segment of the cylinder in idealized form. A solid cylindrical part approximately 12 inches in diameter, is disposed in twelve like segments in this particular example, each encompassing 30 of circumferential arc. Each segment includes the eight different planes A to H of warp yarns in the same predetermined sequence. The warp yarn planes each terminate at the outer surface of the cylinder 100, but the extent to which an individual warp yarn plane penetrates into the cylinder 100 is dependent upon its position in the pattern. The planes of longest radial length (A and E) are 24 levels or fill yarn ends deep. The planes of shortest radial length (D and F) are six levels or fill yarns deep. Through the eight segments the repetitive pattern varies in the sequence 24, 16, 12, 6, 24, 6, l2, 16 in this example. The inwardly directed depths of the planes thus vary repetitively in such fashion that the average warp yarn density at any radius remains substantially the same. The fill yarn may be considered to be woven within separate fill yarn planes at successive longitudinal increments along the cylinder. Within each plane, the fill yarn 104 travels in spiral fashion from the inside out or from the outside in, the spiral varying between adjacent planes. Each individual circular segment of fill yarn 104 may be regarded as substantially concentric with the central axis because of the very small expansion of the spiral from one turn to the next.
In weaving a solid shape such as the cylinder 100, therefore, individual warp yarn planes are interwoven during different intervals of time as the fill yarn 104 is woven in. At the innermost diameter, only the 24-deep warp yarn planes are woven in, but as the fill yarn 104 moves outwardly, it reaches the l6-deep planes and these are then added in along with the 24-deep plane. Thereafter, the l2-deep plane is reached and successively the 6-deep plane is reached, at which time all of the warp yarn planes are being woven simultaneously until the outer radius is reached, following which the operation reverses. Stuffer yarns (not shown) may be added in longitudinally along the body 100, parallel to the central axis, if greater strength is desired along this direction.
The yarn relationships are depicted in idealized form in the fragment of the cylinder 100 shown in FIG. 5. The circumferential fill yarn segments 104 are substantially concentric with the central axis of the cylinder, and pass between the interstices defined by the angled warp yarns 106. The warp yarns in the plane of least depth are designated 106, while those in planes of greater depth are designated 106" and 106" respectively.
While fabric products in accordance with the invention are generally impregnated and cured for use as relatively rigid bodies, no such limitation on use should be considered to apply. The fabrics may be employed as flexible conveyors, belts and the like with or without further treatment or the incorporation of an elastomeric matrix. As one example, an approximately hemispheric fabric shape finds application in high temperature, high velocity parachutes.
It should specifically be noted that a number of techniques can be utilized as desired to modify the characteristics of fabrics in accordance with the invention. The filaments themselves can be woven in one state, and thereafter converted to another state or chemical composition. Wool and like materials, for example, can be shrunk to much higher. density. Leaching and pyrolysis treatments can be used not only to shrink the fabric and thereby achieve higher density, but transform the starting material to another, essentially different material. Thus glass fibers may be leached to remove nonsiliceous constituents, or organic polymer fibers may be thermally decomposed to eliminate non-carbonaceous constituents. Both processes involve shrinkage, the former resulting in essentially silica fibers while the latter results in essentially carbon fibers.
Although the invention has been described above in terms of certain methods and machines for producing woven fabrics, and the woven fabrics produced thereby, it will be understood that the invention is intended to encompass all modifications and variations falling within the scope of the appended claims.
What is claimed is:
1. A thick walled, flat fabric body comprising:
a plurality of warp yarn planes disposed along the length of the fabric and normal to opposite, planar, broad faces of the fabric, each of the warp yarn planes defined by a plurality of warp yarns, each warp yarn traversing along angled paths across a substantial part of the thickness of said body between said opposite, planar, broad faces, successive warp yarns being incrementally displaced within a warp yarn plane to define interstices between locally intersecting segments of said warp yarns;
a plurality of fill yarn lengths disposed within the interstices defined within said warp yarn planes, said fill yarn lengths lying substantially normal to said warp yarn plane at the region of the intersection and substantially parallel to said opposite, planar, broad faces of said body, there being in excess of approximately four fill yarn levels;
and wherein said warp yarns and fill yarns comprise substantially quartz yarn material, wherein said fabric body has more than approximately 100 warp ends per inch and 250 picks per inch, and wherein the density in the as-woven form is above about lbs/ft.
2. A thick walled, flat fabric body comprising:
a plurality of warp yarn planes disposed along the a plurality of fill yarn lengths disposed within the interstices defined within said warp yarn planes, said fill yarn lengths lying substantially normal to said warp yarn planes, at the region of intersection and substantially parallel to said opposite, planar, broad faces of said body, there being in excess of approximately four fill yarn levels;
and wherein said warp yarns and fill yarns comprise substantially carbon yarn material, wherein the density of the body is above approximately 25 percent of the density of carbon, and wherein said fabric body has in excess of approximately 130 warp ends per inch and 200 picks per inch and wherein the density in the as-woven form is above about 30 lbs/ft.
3. A thick walled, flat fabric body comprising: a plurality of warp yarn planes disposed along the length of the fabric and normal to opposite, planar, broad faces of the fabric, each of the warp yarn planes defined by a plurality of warp yarns, each warp yarn traversing along angled paths across a substantial part of the thickness of said body between said opposite, planar, broad faces, successive warp yarns being incrementally displaced within a warp yarn plane to define interstices between locally intersecting segments of said warp yarns;
plurality of fill yarn lengths disposed within the interstices defined within said warp yarn planes, said fill yarn lengths lying substantially normal to said warp yarn planes, at the region of intersection and substantially parallel to said opposite, planar, broad faces of said body, there being in excess of approximately four fill yarn levels;
and wherein said warp yarns and fill yarns comprise substantially nylon yarn material, wherein the density of the body is approximately 50 percent of the density of nylon and in the as-woven form is above about 35 lbs/ftx", and wherein said fabric body has in excess of approximately 100 warp ends per inch and 200 picks per inch.
4. A thick walled, flat fabric body comprising: a plurality of warp yarn planes disposed along the length of the fabric and normal to opposite, planar, broad faces of the fabric, each of the warp yarn planes defined by a plurality of warp yarns, each warp yarn traversing along angled paths across a substantial part of the thickness of said body between said opposite, planar, broad faces, successive warp yarns being incremenetally displaced within a warp yarn plane to define interstices between locally intersecting segments of said warp yarns;
a plurality of fill yarn lengths disposed within the interstices defined within said warp yarn planes, said fill yarn lengths lying substantially normal to said warp yarn planes, at the region of intersection and substantially parallel to said opposite, planar, broad faces of 'said body, there being in excess of approximately four fill yarn levels; and wherein said warp yarns and fill yarns comprise substantially glass yarn material, wherein the density of the body in the as-woven form is above about40 percent of the density of glass and above about 65 lbs/ft, and wherein said fabric body has in excess of approximately warp ends per inch and 200 picks per inch. 5. A thick walled, flat fabric body comprising: a plurality of warp yarn planes disposed along the length of the fabric and normal to opposite, planar, broad faces of the fabric, each of the warp yarn planes defined by a plurality of warp yarns, each warp yarn traversing along angled paths across a substantial part of the thickness of said body be tween said opposite, planar, broad faces, successive warp yarns being incrementally displaced within a warp yarn plane to define interstices between locally intersecting segments of said warp yarns; plurality of fill yarn lengths disposed within the interstices defined within said warp yarn planes, said fill yarn lengths lying substantially normal to said warp yarn planes, at the region of intersection and substantially parallel to said opposite, planar, broad faces of said body, there being in excess of approximately four fill yarn levels;
and wherein said warp yarns and fill yarns comprise substantially rayon yarn material, wherein the density of the body is above approximately 40 percent of the density of rayon and above approximately 40 lbs/ft, and wherein said fabric body has in excess of approximately 100 warp ends per inch and 200 picks per inch.
6. A thick walled, flat fabric comprising:
a plurality of warp yarn planes lying substantially transverse to the thickness of the fabric between opposite, planar faces thereof, the warp yarns in the planes traversing diagonal paths of successively alternating direction along the paths, said warp yarns traversing at least the major portion of thickness of the fabric along each diagonal, fill yarns disposed transversely to the warp yarn planes substantially parallel to the opposite, planar faces of the fabric, the fill yarns filling the interstices between the warp yarns, the fabric being substantially homogeneous, the filaments establishing a density of the body in excess of approximately 20 percent of the density of the material of the fabric, the fabric being non-laminar in character and having in excess of about 100 warp ends per inch, about 200 picks per inch, and about 20 lbs/ft. density in the as-woven form.
7. A non-laminar, thick, flat fabric element comprising a plurality of warp yarn planes disposed along the length of said fabric, said warp yarn planes being substantially transverse to the broad faces of said fabric, each warp yarn plane being defined by a plurality of warp yarns disposed in successive zigzag paths along said fabric, said zigzag paths for each warp yarn being successively incrementally advanced relative to the other warp yarns, there being in excess of 10 warp yarns per plane and the warp yarns intersecting in multiple fashion to define a plurality of interstices within tire structure thus being interlocked, the thickness of the fabric being in excess of one-fourth inch, and the density of the filamentary constituent of the fabric in the as-woven form being in excess of 20 percent of the theoretical density of the material of the yarn.
l t =1 t t mg UNITED STATES PATENT OFFICE CERTIFICATE OF CO'RRECTEON Patent No. 3.742.138 Dated August 31. 1973 Inventor(s) Walter A. Rheaume and Arthur R. Campman It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: I
Column 1, line 6, strike out the comma, first and second Occurrence. Column 2, line 3, for "whice" read' which line 56, after "Fig. 4" insert a comma lines 60-67, delete in its entirety. Column 3, lines 1-24, delete in its entirety. Column 4, line 27, strike out "leven"; line 28, after "level" insert --and--' line 29, for "8" read --2-. Column 6, line 30, for "30,9" read -30.9+-'. Column 7, line 1, for "Of" read --,of-- line 4, delete the comma; line 13, for "produce" rea'd --product-- Signed and sealed this 25th day of December 1973.
RENE D. TEGTl [EYER EDWARD M .FLETCHER, JR.
Acting Commissioner of Patents Attesting Officer