Patent Application
20090194899
(1) Field of the Invention
The present invention relates to an adjustable air shield for skewed godet rolls in a relax zone during yarn production. Both the adjustable air shield and the adjustable skewed godet rolls are incorporated into a relax zone in the production of yarn to increase the stability of the yarn on the relax rolls, especially at process speeds greater than about 4,000 meters per minute. The skew is changed to accommodate processes that have different deniers (width of filament band on the rolls) and a different number of wraps on the rolls. Typical processes that have apparatus for relaxing the yarn during production are spin-drawing, draw-twisting, draw-winding, and draw-bulking processes. There is thus a need for a design of adjustable air shields to accommodate changes in roll skew.
(2) Prior Art
The following patents relate to employing an air shield during yarn production. Generally these patents teach employing an air shield near a pair of godet roll. None of these patents teaches employing adjustable air shields.
Japanese Patent 58-26767 to Ishihara Masatoshi, et al. assigned to Toray Industries, Inc., describes air shield plates used to prevent yarn vibration thereby enhancing the quality of the wound yarn in high speed winding applications. This patent employs restricting guides as well as the air shield plates in FIG. 2 of JP 58-26767.
Japanese Patent 62-116477 to Ohata Takahiro, et al. assigned to Teijin Seiki Company, Ltd., discloses an air shield plate positioned between a pair of godet rolls to prevent the occurrence of vibration of the yarn.
Korean Patent Applications 94-4689 and 94-4690 by Baek, et al. and assigned to Cheil Synthetics, Inc., both relate to employing multi-hole air shield plates near the first godet roll to be used at high speeds above 6,000 meters per minute to prevent air flow thereby reducing fiber breakage and ensure high productivity of the process.
Japanese Patent 2761789 to Takashi Inoue, and assigned to Teijin Seiki, Co., Ltd., describes an air shield type device. Specifically, two godet rolls are employed where yarn moves excessively on the roll surfaces. Each godet pair consists of a driven roll and a separator roll. The air shield is a single plate mounted between the rolls with one edge in close proximity to the driven godet roll surface. The plate is perforated with multiple holes which break up the deflected air stream that bounces off the plate and reduces the incidence of roll wrap.
Published PCT application PCT US02/00153 filed Jan. 3, 2002 discloses at least a pair of godet rolls with at least one air shield. There is no teaching of adjustability of the air shields with respect to the skewed rolls. This patent application has a common inventor and is commonly assigned.
The fixed shields, relative to the godet rolls, in the prior art devices do not allow for the skew of the rolls to be changed (or adjusted) without changing the geometry and thus the efficiency of the air shields. The skew is changed to accommodate processes that have different deniers (width of filament band on the rolls) and a different number of wraps on the rolls. There is thus a need for a design of adjustable air shields to accommodate changes in roll skew.
The present invention relates to an adjustable air shield for skewed godet rolls. The air shield can be any blocking type plate with or without perforations. Furthermore, these air shields may be placed in close proximity to the pair of adjustable skewed, relax rolls in the relax zone of a fiber producing process. The plates are positioned on the inside of the threadline so that the airflow is substantially reduced around the threadline on the skewed rolls. The preferred embodiment of the present invention is one or more skewed godet rolls in the relax area of the fiber production process with air shields positioned on the inside of the fiber string up (threadline) between the pair of skewed rolls, such that the gap between any roll and any air shield is uniform and constant.
In the broadest sense, the present invention comprises, for use in a relaxation zone of a fiber production process, an adjustable air shield and a pair of skewed godet rolls.
Likewise, the present invention relates to a process for producing fibers in a relax zone having a pair of skewed godet rolls, comprising the step of introducing an adjustable air shield adjacent at least one of the skewed rolls (relax rolls) in the fiber relaxation zone. Thus when the skew of the rolls is reset to accommodate different yarns, the air shield is adjusted such that the gap between any roll and any air shield is uniform and constant.
The drawings are to aid one skilled in the art in understanding the present invention and its related concepts as well as the scope of the invention. However, the drawings are in no way meant to limit the scope of the invention or impose any limitation on the invention beyond that set forth in the claims.
The present invention is directed to adjustable air shields and skewed godet rolls in a relax zone of a yarn production process. By godet rolls, the inventors are referring to any pair of rolls that has a threadline wound around them. Sometimes the industry refers to a godet roll and a separator roll, or one or more relax rolls. All of these various references are included under the phrase “godet rolls”. Current processes such as a spin draw process, draw twisting process, draw-winding process, or draw bulking process include a relax zone and thus the process and apparatus of the present invention can be employed in such a relax zone.
Any melt-spun polymer employed with any of the above processes such as polyesters, polyamides (nylons), polyolefins, polyketones, polyetherketones, polyphenylene sulfide, and polyarylates can be employed with the present invention. Typical polyesters are polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, or a mixture of any of these, or copolymers of any of these polyesters with up to about 15% by weight of other comonomers, such as isophthalic acid. Typical nylons are nylon 6 and nylon 66. Typical polyolefins are polyethylene, polypropylene, polybutylene, or a mixture of these. Combinations of any of these polymers, or any one of these polymers with other polymers like polyethylene or polypropylene, in the form of a bicomponent or heterofil fiber are also within the scope of the present invention.
As the relax level increases, yarn tension in the relax zone decreases, and this causes the yarn to become unstable, especially on skewed godet rolls in or downstream of the relax zone. As process speeds increase, instability becomes worse at a constant relax ratio, due to the increase in centrifugal force on the yarns on the skewed relax rolls. Thus as process speeds are increased, relax level must be decreased to maintain stability. Unstable yarn is defined as yarn moving, or swaying across the roll surface of the skewed godet rolls due to low tension. Highly unstable yarn can lead to a reduction in mechanical quality, and in severe cases, to breakouts (yarn breakage). The skew for godet rolls is different for different process conditions, such as denier of the yarn, process speed, amount of relax, and type of synthetic yarn, for example. Therefore, the skew of godet rolls may be varied to accommodate running different products on the same equipment.
When the process or apparatus of the present invention is used in any of the yarn production processes having a relax zone, a higher level of relax and a resulting lower hot air shrinkage can be achieved as compared to conventional processes and apparatus having no air shields. By using the present invention at higher processing speeds one can achieve the same level of relax under high speed conditions versus more conventional low speed conditions, or one could maintain the process speed but increase the level of relax such that the hot air shrinkage is greatly improved (reduced), or both can be done simultaneously.
The air shield is positioned inside of the threadline 16 so that airflow is blocked from blowing across the threadline and creating movement on the skewed rolls 12, 14. The air shield 18 comprises at least one plate (thin and flat substantially two dimensional) and preferably a pair of plates are employed, one per roll as shown. The plates may be made from any material capable of being perforated or being solid such as metal, like aluminum or copper for example (virtually any metal will perform equally well); plastic capable of withstanding the heat generated during the relaxation stage of the fiber making process, like polycarbonate, polyester, polyamide, all of which are well known in the art; wood, rubber; or a combination of these. The air shield may be any shape, not necessarily rectangular or square, because the rolls 12, 14 are skewed. Preferably the spaced apart plates 18 are positioned between the skewed rolls 12, 14 and within each tangent line connecting the outer surface of each roll, and thus within the threadline 16. When one air shield is used per roll as shown in
In operation of the
The operation of the
Those skilled in the art may recognize that a larger diameter roll like roll 12 would create more air currents at its larger surface than a smaller diameter roll like 14. Thus its within the present invention to have 3 air shields where the larger roll has a pair of shields while the smaller roll has only a single air shield. Likewise, it is within the skill of the artisan to provide only one air shield at the exit side of the threadline adjacent the larger roll, and no air shield on the smaller roll.
Thus it is apparent that there has been provided in accordance with the invention a process and an apparatus that fully satisfies the objects, aims, and advantages set forth above. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit and the broad scope of the claims.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US04/24824 | 7/30/2004 | WO | 00 | 1/29/2007 |
