1. Field of the Invention
This invention relates generally to fabrics for forming sleeves for receiving and protecting elongated items such as wiring harnesses and optical fiber cables, and more particularly to warp knitted self-curling fabrics therefor.
2. Background of the Invention
Protective sleeving is used throughout the automotive, marine and aerospace industries to organize and protect elongated items, such as wiring harnesses and optical fiber cables, for example. The sleeving surrounds the elongated items and protects them against cuts, abrasion, radiant heat, vibration induced wear and other harsh environmental threats. When positioned within protective sleeving, the wiring or cables are also held together in a neat bundle, allowing a multiplicity of different items to be handled as a sub-assembly, thus saving time and effort during integration of the items into its end environment.
Protective sleeving may be made by weaving or knitting filaments into a substrate and then resiliently biasing the substrate into a tubular form to define a central space for receiving the elongated items. Biasing may be effected by heating the filaments when the substrate is wrapped about a cylindrical mandrel, wherein the filaments take on a permanent set conforming to the shape of the mandrel. In addition, filaments can also be resiliently biased into a curved shape by applying chemicals thereto, as well as by cold working.
When substrates are biased into a tubular shape via the mechanisms described above, monofilaments are typically oriented in the “hoop” or circumferential direction of the tube. Monofilaments provide excellent stiffness and provide strong resilient biasing that maintains the substrate in the tubular shape. The biased monofilaments also tend to restore the substrate to its tubular shape in the absence of a distorting force, which is generally applied when the sleeve is manipulated to an open state to insert or remove an elongated item.
A significant disadvantage associated with sleeves that are biased into a tubular shape is that the biasing is effected by a separate step in the process of making the sleeve. The filaments comprising the substrate may be biased by cold working before manufacture of the sleeve or may be biased afterward by heating the substrate when wrapped about a mandrel, but these actions constitute an additional process that adds to the cost and the time required to produce the sleeve. Accordingly, it would be advantageous to be able to manufacture a tubular sleeve from a substrate that negates the need for secondary processes to impart the tubular shape on the substrate.
The invention concerns a knitted self-curling fabric having warp stitches and a plurality of weft stitches. The fabric comprises a chain stitch of a first multi-filament yarn forming the warp stitches, a lay-in stitch of a second multi-filament yarn forming one of the weft stitches and a tricot stitch of a monofilament forming another of the weft stitches. The tricot stitch is positioned predominantly on one face of the substrate. The tricot stitch is knitted under tension and biases the substrate into a self-curled configuration about a central space. To facilitate imparting the bias, the tricot stitch is preferably knitted as a satin stitch.
Another embodiment of a self-curling fabric according to the invention comprises a chain stitch of a first multi-filament yarn forming the warp stitches, a first tricot stitch of a second multi-filament yarn forming one of the weft stitches and a second tricot stitch of a monofilament forming another of the weft stitches. The second tricot stitch is positioned predominantly on one face of the fabric. The second tricot stitch is knitted under tension and biases the fabric into a self-curled configuration about a central space.
Yet another embodiment of a self-curling fabric according to the invention comprises a first chain stitch of a first multi-filament yarn forming the warp stitches, a second chain stitch of a second multi-filament yarn also forming the warp stitches, a lay-in stitch of a third multi-filament yarn forming one of the weft stitches and a tricot stitch of a monofilament forming another of the weft stitches. The tricot stitch is positioned predominantly on one face of the fabric. The tricot stitch is knitted under tension and biases the fabric into a self-curled configuration about a central space.
Another aspect of the invention provides a method of fabricating a self-curling sleeve having a longitudinal axis extending between opposite ends. The method includes warp knitting a plurality of warp yarns and a plurality of first weft yarns together, and inserting a plurality of second weft yarns with the warp yarns and the first weft yarns during the warp knitting step. The second weft yarns cause the first weft yarns to curl about the longitudinal axis.
The embodiments described above may further comprising a filamentary member knitted with the warp and weft stitches. The filamentary member may be positioned predominantly on one face of the substrate and be a heat fusible yarn, an electrically conducting yarn, a thermally insulating yarn, an abrasion resistant yarn, and combinations thereof for tailoring the sleeve to perform a particular function in addition to protecting and bundling of the elongated items.
These and other aspects, features and advantages of the invention will become readily appreciated when considered in connection with the following detailed description of the presently preferred embodiments and best mode, appended claims and accompanying drawings, wherein:
Referring in more detail to the drawings,
The fabric 14 of the sleeves 10, 12 can be made through weft insertion of filaments during warp knitting, or also by warp knitting alone, to produce the force imbalance necessary to induce the fabric 14 to self-curl. The fabric 14 is knitted, preferably using crochet techniques, wherein the movement of needles and guides is horizontal, such as on an Acotronic 400 Crochet machine, for example. As such, the fabric 14 is knitted as a crochet flat knit structure that self-curls into the tubular sleeve 14 upon release of the yarns from the knitting needles. Accordingly, the sleeve 14 takes on its tubular shape wherein the free edges 18 are arranged in overlapping relation with one another without need for secondary processes, such as heat setting, for example. The fabric 14 is preferably warp knitted with the warp-wise direction being substantially parallel to the longitudinal axis 16 and the weft-wise direction being substantially perpendicular to the warp-wise direction.
The fabrics 14 are formed using a combination of filamentary members including both multi-filament yarns and monofilaments. The multifilament yarns are generally the basis of the knit fabric 14 and provide flexibility to the fabric 14 and form the basis for coverage of the elongated items 22. The monofilaments are generally stiffer elements and are knitted under tension, with the tension preferably being maintained constant throughout the knitting process, such that the tension on the monofilaments is greater than any balanced tension imparted on the multifilament yarns. Being predominantly located on one face 24 of the fabric 14, the tension imparted by the monofilaments provides a bias affecting the self-curling characteristics of the fabric 14. The one face 24 on which the monofilaments are located becomes an inwardly facing concave surface 25 of the sleeve 10, 12.
Various example embodiments of the fabric 14 are described below with reference to specific stitch types, needle notation and materials used. It should be recognized that the resulting self-curling fabric 14 is not limited to these specific examples. The schematic stitch illustrations show the presently preferred stitches used to construct the fabric examples, with the various stitches being illustrated separate from one another for clarity. It is to be understood that the various stitches are not formed separate from one another, but are knitted with one another to form the fabric 14 on the crochet machine.
Each stitch diagram represents a separate bar on the crochet knitting machine that carries a plurality of yarns or monofilaments knitted in the stitch that is illustrated. In the first two fabric examples illustrated in
In a related example to Example 1, the plurality of closed chain stitch yarns 28 may comprise one or more monofilaments in place of some of the multi-filament chain stitch yarns over a plurality of wales 29, thereby creating one or more wales of close chain stitch monofilament yarns extending along the length of the sleeve fabric 14. Such circumferentially spaced monofilament wales 29 enhance the abrasion resistance and provide increased protection to the adjacent multifilament yarns. Accordingly, the sleeve 10, 12 could contain both monofilament and multifilament warp-wise chain stitches 28, 29 on the outer convex surface 27. As mentioned above, this example embodies the classic crochet techniques and tends to have less end fray when cold-cut due to aforementioned reasons.
Although specific deniers for the yarns and diameters for the monofilaments are provided in the examples above, as mentioned, it is understood by those possessing ordinary skill in the crocheting and knitting arts that other yarn deniers and monofilament diameters are also feasible. In fact, fabric 14 constructed in accordance with the invention could be made with multifilament yarns ranging between about 100-1000 denier and monofilaments ranging between about 6-12 mils. In addition, unidirectional and semi-unidirectional filaments can be added, such as by being knitted or served with the warp and weft stitches for increased product performance, such as, for mechanical, EMI/RF and/or thermal shielding, for example. Some preferred additions could be aramid, electrical or EMI/RF shielding materials, polyarnide, glass, PPS, and PEEK, for example, depending on the application. Other additions of fire-retardant, chemical resistant, heat fusible, electrically conductive, thermally insulative, and abrasion resistant yarns or filaments are also anticipated.
In accordance with another aspect of the invention, methods of fabricating the sleeves described above are embodied herein, including warp knitting and weft-insertion warp knitting. One such method for fabricating a self-curling having a longitudinal axis extending between opposite ends includes warp knitting a plurality of warp yarns and a plurality of first weft yarns together, and inserting a plurality of second weft yarns with the warp yarns and the first weft yarns during the warp knitting step. The insertion of the second weft yarns under tension causes the first weft yarns to curl about the longitudinal axis upon release of the second weft yarns from the knitting process. Accordingly, no secondary processes or fastening mechanisms are required to bring the sleeve into its curled shape.
Additional aspects of the method of fabrication can further include using a multifilament yarn for the warp yarns and for the first weft yarns. In addition, the method contemplates using a monofilament for the second weft yarns, wherein the monofilament is inserted under tension, as already discussed. Further, the method contemplates using a monofilament for at least one of the warp yarns or the first weft yarns. It should be recognized that some of these methods can be used in combination with one another, while some require the exclusion of others. For example, if a specified yarn is a monofilament, then it can not be at the same time a multifilament. Of course, this will be readily apparent to those having ordinary skill in the art of textile fabrics.
Self curling fabrics fabricated according to the invention provide a protective sleeve that accommodates elongated items, and that may be manufactured more economically by avoiding additional process steps associated biasing the substrate into a curled sleeve in secondary operations, such as by cold working, heat treatment or chemical processes. As mentioned, they also eliminate the necessity for fasteners to maintain the sleeves in their tubular shape, although, if desired, various fastening mechanisms could be incorporated to provide a redundant closure mechanism, such as hook and loop fasteners, for example.
Obviously, many modifications and variations of the present invention are foreseeable in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described for the presently preferred embodiments.
This application is a continuation-in-part of U.S. patent application Ser. No. 11/185,589, filed on Jul. 20, 2005 now U.S. Pat. No. 7,216,678, which claims the benefit of U.S. Provisional Patent Application Ser. No. 60/589,270, filed Jul. 20, 2004 and U.S. Provisional Patent Application Ser. No. 60/657,847, filed Mar. 2, 2005. This application also claims the benefit of U.S. Provisional Patent Application Ser. No. 60/754,882, filed on Dec. 29, 2005, and U.S. Provisional Patent Application Ser. No. 60/782,422, filed on Mar. 15, 2006, and incorporates all of these applications herein by way of reference in their entirety.
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Number | Date | Country | |
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Parent | 11185589 | Jul 2005 | US |
Child | 11616983 | US |