US 3586063 A
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United States Patent Robert P. Bell, Jr.
Cary, N .C.;
Marvin A. Eaton, Decatur, Ala. 774,966
Nov. 12, 1968 June 22, 1971 Monsanto Company St. Louis, Mo.
Inventors Appl. No. Filed Patented Assignee FABRIC AND METHOD FOR WEAVING 5 Claims, 6 Drawing Figs.
US. Cl 139/425, 139/1 16 Int. Cl 003d 15/02 Field olSearch 139/116,
References Cited UNITED STATES PATENTS Rossmann Osterheld Hornbostel et al. Mackay Willmann Claya Primary Examiner-Henry S. .laudon Attorney-Robert L. Broad, Jr.
ABSTRACT: A woven fabric of relatively inextensible materials wherein the warp threads lie substantially straight and in a common plane, and the fill threads traverse a sinusoidal path alternating above and below the warp threads is produced by placing the fill thread in the warp shed at a fixed angle of inclination to the warp threads so that the length of fill is substantially greater than the width of warp.
PATENTEU JUH22 I971 FIG. 5.
INVENTORS ROBERT R BELL,JR MARVIN A. EAT 0g 76w; KM
ATTORNEY FABRIC AND METHOD FOR WEAVING BACKGROUND OF THE INVENTION This invention relates to a method for weaving fabrics, and more particularly to a method for weaving highly inextensible materials into fabrics having a straight warp and curvilinear fill.
Recent developments in the field of high strength, temperature resistant materials have included the use of inorganic refractory fibers such as boron, boron nitride, boron carbide, silicon, silicon carbide, alumina, alumina-silica, carbon, glass, and quartz to fabricate reinforced composite structures having outstanding stiffness and strength-to-weight ratios. These inorganic refractory fibers are characterized by high strength and modulus, brittleness, limited flexibility, and by essentially zero elongation as defined by the term inextensible.
Although many of these refractory fibers are presently available only in short lengths or as whiskers, efforts are being made to produce the materials in continuous filament form. Continuous filament boron formed by the vapor deposition of boron on a fine wire tungsten substrate is now commercially available.
High-strength reinforced structures are generally fabricated either by filament winding or by sheet layup. In filament winding, strands of reinforcement are oriented directly onto surfaces which control their form. In sheet layup, the strands are first formed into sheets, and the sheets are laid up and laminated to provide the desired form and orientation. While these methods are useful, composites made by these processes do not possess the cross-reinforcement provided by a woven structure. For this reason, it is desirable to prepare woven fabrics of the inextensible materials as reinforcement for composite structures.
Although the art of weaving is ancient, the inextensible and brittle nature of the inorganic refractory fibers precludes their processing on conventional weaving equipment. We have found that when attempting to weave two relatively inextensible materials such as continuous filament boron warp and a continuous filament fiber glass fill, the boron filaments are broken with great frequency due to the high stresses occurring at the point of weaving as a result of the inextensibility of the warp and fill yarns. In order to prevent the formation of high stresses and breakage of the boron filaments, it was necessary to introduce some slack into the fill yarn and thereby relieve the tension between the warp and fill material.
SUMMARY OF THE INVENTION It has been discovered that by laying the fill yarn obliquely through the warp shed at a controlled angle of inclination to the direction of the warp, it is possible to precisely control the length of the filling yarn when the yarn is relocated normal to the warp by the action of the beaters. The resulting fabric is characterized by having straight warp yarns lying in a single plane. with the filling yarn describing a sinusoidal pattern when viewed in cross section as it passes alternately over and under the straight warp yarns.
The warp yarns employed in the practice of this invention are commonly the inorganic refractory fibers which are brittle, highly inextensible and of limited flexibility, while the fill yarns are commonly fiberglass which although highly inextensible, is nevertheless very flexible.
It is therefore an object of this invention to produce a woven fabric of highly inextensible materials.
It is a further object of this invention to provide a method for controlling the filling length during weaving in order to provide slack in the fill yarn and relieve tension in the fabric.
Other objects and advantages of the invention will become apparent when the following detailed description is read in conjunction with the drawings.
DESCRIPTION OF THE DRAWING FIG. I is a representation illustrating the relationship between the warp and fill yarns during the shedding operation.
FIG. 2 shows a section of the uniform fabric produced in accordance with this invention.
FIG. 3 shows a cross section of this fabric in the warp direction.
FIG. 4 shows a section of the high tension fabric produced in accordance with the weaving processes of the prior art. FIG. 5 shows a cross section of this fabric in the warp direction.
FIG. 6 depicts one possible arrangement of the apparatus to accomplish the method of the instant invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now in detail to the drawings, there is shown in FIG. I a critical angle, I existing between the orientation of a warp l0 and fill yarn 11 during the filling operation and before the beating action. In the drawing, a given length of fill yarn AC exceeds the width of warp AB by an amount equal to 1 B (cos The optimum value of angle I is determined by a number of factors, such as the diameter of the warp threads, the diameter of the fill yarn, and the closeness of the weave. If angle I is too large, the fill yarn will lie slack and the fabric will lack dimensional stability. Ideally, the angle 1 adjusted experimentally for the particular fabric being woven by laying the fill yarn 11 at some predetermined angle to the longitudinal axis of the warp so that the fill yarns lie snuggly about the warp but do not impart any significant degree of stress or tension to the warp. As a practical matter, angle 4 will generally be between 30 and 60, whereby the length of fill yarn exceeds the linear width of the warp by 15 to percent.
When angle b is at an optimum value, the warp 10 of the woven fabric lie straight and parallel in a common plane as shown in FIG. 2, and the fill yarn 11 passes snuggly over and under alternate warp without deflecting the warp as depicted in FIG. 3. In contrast, FIGS. 4 and 5 show corresponding views of a typical fabric wherein failure to provide excess length of fill yarn 11 has resulted in deflection of the warp l0 and imparted high stresses to the fabric.
In the practice of this invention, provision must be made to provide slack in the fill yarn during the beating step in order to assure that the fill yarn is moved along the warp yarns with no lateral displacement. Referring to FIG. 1, the fill yarn I1 is placed between a warp shed along line AC. After beating, the fill is relocated along line AB, and point C is superimposed on point B.
One possible apparatus and method which may be successfully employed in the practice of this invention to control the angle 9 and provide the necessary slack in the fill yarn is depicted schematically in FIG. 6. The sequence of the weaving operation is as follows: (1) I-Ieddles 12 open to form a warp shed l4 (2) A shuttle 15 is passed through the warp shed 14 from position 6. (3) Fill yarn 11 is carried by the shuttle l5 and laid along path AEG. Rod 17 connected to the weaving apparatus at point E is a moveable guide rod which is positioned to control angle b, the rod 17 being stationary during the weaving operation. (4) A strip rod 13 slidably attached on the weaving apparatus and provided with means (not shown) for moving said rod 17 within a predetermined path from a position F to a position F, thereby stripping additional fill yarn from the shuttle l5 and imparting considerable slack in the fill yarn ll. (5) The heddles 12 close the warp shed 14 and beater I6 slides the fill yarn 11 down the warp to a position corresponding to AB. (6) The heater I6 returns to its original position, and the process is repeated in the opposite side where guide rod 18 and strip rod 19 corresponding to rods 17 and 13, respectively, await to engage the fill yarn.
The above mechanism can be used with good results, but any mechanical arrangement to provide the functions of rods 17 and 13 can be substituted with equal success. The instant invention is therefore not limited to any particular mechanical arrangement, but rather to the novel method involved in the practice thereof as defined in the following claims.
1. A method for weaving a fabric of essentially inextensible materials, said fabric being characterized by having a straight parallel warp and having a fill yarn traversing a sinusoidal path alternating above and below said warp, said method comprising the repeating steps of a. forming a shed in the warp,
b. laying a fill yarn through the shed at an angle to the longitudinal axis of the warp of between 30 and 60, whereby the length of fill yarn exceeds the linear width of the warp by 15 to 100 percent,
c. inducing slack into the fill yarn through stripping additional fill yarn from a shuttle while maintaining the angle between the fill yarn and the warp constant, and
d. slideably moving the fill yarn in a direction parallel to the warp until the longitudinal axis of the fill yarn is at substantially right angles to the longitudinal axis of the warp.
2. The method of claim 1 wherein the warp is inextensible filamentary material comprised of a tungsten core with a sheath selected from the group consisting of boron, boron carbide, and titanium diboride.
3. The method of claim 1 wherein the warp is highly inextensible inorganic refractory fibers selected from the group consisting of boron, boron nitride, boron carbide, alumina, alumina-silica, silica, and silicon carbide.
4. The method of claim 2 wherein the fill yarn is comprised of continuous glass fibers.
5. A highly inextensible woven fabric comprising a warp of straight and parallel inorganic refractory fibers selected from the groups consisting of boron, boron carbide and titanium diboride and a fill of continuous glass fibers describing a sinusoidal path alternately above and below the warp fibers.
UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3,586I 3 Dated June 22L 1971 Inventor(s) Robert P. Bell, Jr. et 31 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
C01. 1, line 55, after "yarn" insert --to exceed the width of the warp, and thereby provide for slack in the fill yarn-.
igned and sealed this 30th day of January 1973.
EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM powso 0459) USCOMM-DC scam-ps9 Q U 5 GOVERNMENT PRINUNG OFICE 1959 O-3G6 3ll