Textiles: weaving – Stopping – Warp
Reexamination Certificate
1999-11-10
2003-06-10
Calvert, John J. (Department: 3765)
Textiles: weaving
Stopping
Warp
C139S192000, C139S386000, C139S38400B
Reexamination Certificate
active
06575201
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a weaving method and an apparatus for producing a fabric with variable width.
JP 7-238433 discloses a woven tube whose diameter is changed along the length in that weft threads of different elasticities are inserted in the warp direction.
Fabrics can be produced both as a two-dimensional, one-layered sheet and in the form of multi-layered, thicker structures. Woven tubes with diameters variable along their lengths could up to now not be produced without seams because the known methods for changing the width of the fabric are not applicable in this case.
One possibility for changing the width of the fabric resides in the concentration and spreading of the warp threads. In doing so, the overall number of the warp threads in the fabric remains constant. Of course, the width of the fabric and thus possibly also the diameter of a woven hollow space is changed in the process; however, the spreading and also the contraction of the lateral distance between the warp threads are resisted by the warp thread tension, the weft insertion and the weft thread tension, which is inevitable and for other reasons even desired. The spreading and thus the contraction are thus not stable and will essentially be lost during the weaving. Therefore, a desired change of width cannot be easily performed.
It is an object of the invention to provide a weaving method and a weaving apparatus which is able to produce a stable fabric of threads, especially weft threads, of uniform elasticity and stretchability and with a width that can be varied along the length of the fabric, particularly a tube-shaped fabric whose diameter varies along the length, and in such a manner that very considerable changes of width can be performed per length unit. The change of diameter is to be effected not by the elasticity and stretchability of the threads but by the weaving method itself.
SUMMARY OF THE INVENTION
The above and other objects and advantages of the invention are achieved by the provision of a weaving method and apparatus wherein the reed is displaced so as to change the warp thread spacing and thus the width of the advancing fabric in accordance with a predetermined program which represents a desired fabric width which varies along the length of the sheet of warp threads. At least the two opposite edges of the formed interwoven fabric are engaged with spreader devices which impart a width guiding effect to the engaged opposite edges. Also, the width guiding effect is adjusted as a function of the desired fabric width.
The invention offers the advantage that the spreading of the fabric, which is per se known and usual, is utilized actively here for adapting the lateral warp thread position and the weft-thread deposit and tension to the width of the fabric. This makes it possible to obtain strong conical enlargements or reductions of the fabric width which will be permanently applied to the fabric structure and be rigidified therein.
The terms “spreaders” or “spreader devices” are used herein to designate known devices which exert a spreading effect on the fabric.
Particularly preferred are spreaders which are used only on the edges of the fabric. Such spreaders are e.g. needle-equipped circular cylindrical rollers arranged for free rotation in the region of the edge of the fabric. The edge of the fabric is guided via these rollers while partially wound around them. The end faces of the rollers are preferably arranged in parallel to each other but inclined to a radial plane of the rollers. This results in an outward conveying effect. According to the invention, these rollers, with respect to the fabric width, are displaced toward the outside or the inside synchronously and substantially proportionately to the spreading or contraction of the warp thread distance.
Further known are spreaders in the form of non-rotating or rotating rods extending across the width of the fabric. These are e.g. rods wherein the circumference contacting the fabric is provided with grooves facing toward the outside in the direction of the production of the fabric.
When producing fabrics with varying width, the closest contraction depends on the largest possible warp thread density. When spreading such a warp thread sheet, the problem occurs that the warp threads will not become distributed in a uniform manner across the spread fabric width. This problem is solved by the weaving method wherein two or more immediately adjacent warp threads are guided without mutual tying as is the case e.g. with a longitudinal filling rep with 4 warp ascents and 4 warp descents. Such a tying offers the advantage that the friction between the warp threads and the weft threads is low so that the warp threads also after the weft insertion can be distributed across the fabric width due to their inherent tension.
A special form of the fabric is the circular or tube fabric. A tube is woven e.g. in that two fabric layers are produced to lie above each other, being connected only in the edge regions.
In prior methods for weaving tube-like structures, a constant fabric width is generated. The diameter of the woven hollow space, mostly a woven tube, will thus be constant. In many applications, however, a hollow-space-forming fabric is desired which has a more or less tapering diameter or a constant conicity between two different diameters or widths. Examples thereof are fiber reinforcements for poles (sail or surf masts, supporting buttresses) which in the upper region have a small diameter and down to the base have a gradually increasing diameter. Other examples are golf clubs and many light construction rods and supporting arms in industry.
Conically tapering structures with hollow spaces can up to now be produced only by the winding method or the braiding method. The winding method is very time-consuming and is restricted by the danger that threads on the winding core might slide off. The winding method is not suited to place threads in the circumferential direction of a tube and thus is confined to torsion-stressed applications.
The disclosed embodiments of the invention have the object to produce a woven structure which forms a hollow space, e.g. in the manner of a tube, and whose threads extend in the axial and circumferential directions, and whose hollow space increases or decreases in the direction of the warp threads.
In one embodiment, the shuttle weaving technology is of advantage since, in this case, the weft thread, while being uncut, will alternately tie the upper and the lower fabric layers so that a seam region will not be generated on the circumference of the woven tube.
When use is made of narrow fabric needle loom automats, the weft thread on one end of the fabric has to be attached by a crochet edge which will cause a more or less distinct protrusion in the warp direction.
Also the use of modern high-performance rapier weaving machines is made possible by the simultaneous production of a plurality of bands or tubes with variable width or variable diameter. This machine also permits the production of a tube shaped fabric with two longitudinal seams, and the material-saving production of a plurality of bands or tubes with variable width/variable diameter. Through an embodiment wherein the edge region of the fabric layers is connected by a crocket edge, the seam region of the tube is reinforced so that the tube can also be subjected to high pressures inside.
An embodiment of the invention makes it possible to produce bands or tubes which, while having a variable width on the one hand and resp. a variable diameter on the other hand, are also curved along their length. For this purpose, use can be made e.g. of conical take-off rollers. Of particular advantage, however, is the use of take-off rollers separated into segments, wherein each segment conveys one or a group of warp threads and wherein the individual segments can be driven at a controllable speed which is different from segment to segment. In this regard, reference is made to DE Patent 39 15 085.
An embodiment of the invention makes
Alston & Bird LLP
Calvert John J.
Muromotol Robert H.
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