1. Field of the Invention
The present invention relates to spiral fabrics, and, more particularly, to such fabrics having stuffers inserted into open areas to reduce the permeability of the fabric.
2. Description of the Related Art
Spiral fabrics wound with coiled filaments are used in such applications as dryers, PMC, and other applications. They are typically assembled using a series of right and left handed monofilament coils. Adjacent coils are connected by pintles, typically formed from a monofilament. The permeability of the assembled fabric may be reduced by insertion of stuffer yarns into the openings formed between adjacent pintles. The stuffers may be extruded or braided and come in a variety of elongated solid geometric shapes. The stuffers may be effectively locked into the fabric structure by heat setting the monofilament or by applying a polymeric resin material at each edge of the fabric. An encapsulated composite of spiral loops, stuffers and resin results. Due to the nature of the manufacturing process, it becomes progressively more difficult to achieve reductions in permeability for wider fabrics approaching 9 meters wide because of the difficulty of inserting the stuffers in the open spaces in the woven fabric.
When significantly lower permeability is required, it is difficult to seal all the space in the fabric because the geometric shapes placed in the fabric fail to intimately conform to the intricate shape of the coiled filaments.
What is needed in the art is a fabric of the above type that has a significantly lower permeability and which is made using a simplified process.
The invention, in one form, is directed to a fabric having a plurality of coiled monofilaments arranged in side-by-side, intermeshing relationship and elongated pintles extending through intermeshed portions of the coiled monofilaments. Elongated stuffer elements extend through central portions of each of the coils in between adjacent pintles. The stuffer elements respond to a given input after insertion to expand and fill the central portion of each of the coils.
The invention, in another form, is directed to a method of forming a fabric having the steps of arranging a plurality of coiled monofilaments in side-by-side intermeshing relationships. Pintles are extended through intermeshed portions of the coiled monofilaments and tubular stuffer elements are extended through central portions of the monofilaments in between the pintles. The tubular stuffer elements are responsive to a given input to expand and fill the central portion of each of the coils and after the stuffer elements are in place they are subjected to the given input.
In yet another form the invention involves a fabric having a plurality of coiled monofilaments in side-by-side intermeshing relationship. Pintles extend through intermeshed portions of the coiled monofilaments between adjacent pintles and tubular stuffer elements extend through central portions of the coiled monofilaments. The stuffer elements are formed from auxetic material to expand in response to tension and fill the central portion of each of the coils.
An advantage of the present invention is the easy insertion of stuffer elements with substantial reductions in permeability.
The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner.
Referring now to the drawings, and more particularly to
After the spiral monofilament, spiral yarns or coiled yarns 14 are interweaved and the pintles 18 are inserted, tubular stuffers are inserted in a CMD fashion. The tubular stuffers 10 are sized to be received in the open spaces between adjacent pintles 18. The stuffer elements 10 are fashioned from material having a property that is responsive to an external input, shown schematically by reference character 20, which causes the stuffer elements to expand and substantially fill the spaces between pintles, as shown by stuffer element 10a to the right of
The external input is selected from one of heat, temperature, light, sound, chemical and tension to cause the stuffer elements to expand in place. The materials may be responsive to the external input to expand in substantially an irreversible condition or remain in the expanded state so long as the input is present.
The advantage of the materials set forth above is that they can be sized to easily fit into the spaces in the coiled fabric between pintles 18 but, in place, subjected to the external input from element 20 to expand them to substantially completely fill the spaces in the fabrics. This enables permeability levels significantly lower than those experienced in prior art coiled or spiral fabrics.
While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.