METHOD AND APPARATUS FOR MODIFYING SPUN TEXTILE YARN

Abstract: A method of modifying surface characteristics, such as hairiness, and trash content by passing a spun yarn (15) through an air jet nozzle (12, 14). Data show reduced hairiness and improved cleanliness over normally wound yarn.

Description: METHOD AND APPARATUS FOR MODIFYING SPUN TEXTILE YARN Background of the Invention This invention relates to a method and apparatus for changing the surface characteristics of a spun textile yarn. More particularly, this invention relates to a method and apparatus for suppressing the hairiness of such yarn while removing loose fiber and contamination. Still more particularly, this invention relates to a method and apparatus for producing desired surface characteristics using a suitable air Jet nozzle. Still more particularly, this invention relates to a new use for existing air jet nozzles to alter the physical characteristics of the surface of previously-spun yarn and to control the hairiness of such yarn. In the textile arts, significant attention has been paid to consideration of the effect of yarn hairiness and its impact on weaving performance. It is a general objective in the art to control the final hairiness of the warp yarn so that yarns in the sheet will separate cleanly and easily. Unfortunately, excessive warp yarn hairiness and clinging affect production yields, guality of final product, and housekeeping efforts. A major difficulty with high yarn hairiness is that clinging hair fibers between warp ends tend to prevent the formation of a clear front shed on the weaving machine. A low yarn hairiness can be obtained in a spinner-bobbin of yarn by controlling traveler type and weight, condition of rings, and plumbing of spindles. Moreover it is desired to make uniform the degree of hairiness on a spindle-to-spindle basis, and to achieve a good average hairiness wherein the ratio of the high to the low is limited. However, the development and commercial acceptance of air jet weaving in the late 1970's has increased the concern of weavers about the effect of hair - 2 - fibers that protrude from the surface of short staple spun yarns. Indeed, air jet weaving generally requires yarns of higher qualities than shuttle weaving to achieve high productivity. An unclear front shed may obstruct the flight of the filling yarn, resulting in a filling stop that was warp induced. It is also known that winding a ring spun yarn causes significant increases in yarn hairiness, sometimes on the order of 100 to 500 per cent. Thus, at the winding stage for spun yarn, prior efforts to suppress or control hairiness in spinning are unfortunately largely negated. Heretofore, no practical method or apparatus was available to wind a ring spun yarn without causing a significant increase in measurable hairiness. A number of prior efforts to lower ultimate sized yarn hairiness have been proposed, but without significant success. For example, efforts to modify the ring spinning machines were not successful in producing a yarn with better locking of the outermost fibers. In the past, however, it had been established that yarn spun from spaced double-creeled roving approached the desired surface properties, but such spinning is no longer widely practiced because of economic reasons. Experimental efforts focused on winding including gas singeing, mechanical cutting, and scraping but no such efforts provided the desired dramatic results. It was also known that tension had a bearing on wound yarn hairiness in that higher winding tension generally resulted in lower wound yarn hairiness. It is believed that this phenomenon occurs because long hair fibers are stripped from the yarn surface when passing through highly-loaded tension discs, thus improving the overall surface characteristics. Nevertheless, despite such efforts to improve the surface characteristics of spun yarn and in particular its hairiness at various stages of the yarn handling processes, only a limited success has been achieved. Thus, it is an overall objective of this invention to control the physical characteristics of spun yarn, and especially the hairiness of spun yarn especially after spinning and winding. By way of further background, yarn hairiness is usually defined as fiber ends and fiber loops protruding above the yarn surface, where fiber loops account for about two-thirds of the yarn hairiness and fiber ends account for the other third. A number of techniques are available for measuring yarn hairiness, although currently measurement by optical and photographic means are generally preferred. In a typical, well-accepted measuring system, the hairiness of the yarn is determined by counting the number of fibers extending beyond the apparent surface of the yarn, and displaying the count.for a predetermined period of time to obtain an objective count of the hairiness of the yarn for a unit length of yarn. It is thus an overall objective of this invention to improve the surface characteristics of spun yarn. It is an additional objective of this invention to improve the surface characteristics of spun yarn by controlling yarn hairiness. It is still another objective of this invention to improve yarn hairiness in spun yarn by using an air jet nozzle or air vortex produced by a nozzle. It is another overall objecti e of this invention to improve the physical characteristics of the surface of spun yarn by passing the spun yarn through an air jet nozzle. It is still another specific objective of this invention to improve the physical characteristics of the surface of spun yarn by passing the spun yarn through an air jet nozzle in a direction opposite to the yarn direction during spinning. It is yet another objective of this invention to improve the physical characteristics of the surface of - 4 - spun yarn by passing the spun yarn through an air jet nozzle and controlling the angle of exit from the nozzle. It is yet another objective of this invention to remove dust, loose fiber, seed coat contamination, and other impurities in spun yarns by passing the spun yarn through an air jet nozzle or air vortex produced in a nozzle. It is still another general objective of the invention to remove contamination from yarn during a winding process. It is another objective of the invention to modify a yarn with a jet nozzle to improve contamination removal during winding. These and other objectives and aims of the invention will become apparent from a written description of the invention which follows when taken in conjunction with the accompanying drawings. Brief Summary of the Invention Directed to achieving the foregoing objects, and to overcoming the problems of the prior art, the invention in one of its aspects relates to altering the surface characteristics of spun yarn by moving compressed air in a direction perpendicular and opposite to yarn movement. In another aspect, the invention relates to a method of passing a length of spun yarn through an air jet nozzle, thus causing long fibers to wrap around the yarn surface. Surface contamination is also stripped away by the force of the applied airstream. The invention in another aspect relates to a new use of a conventional Murata jet nozzle of the type having two zones, a first imparting a counterclockwise air vortex, the other imparting a clockwise air vortex, each having a vortex speed on the order of 300,000 revolutions per minute. By moving the yarn axially in a direction reverse from that normally used in the Murata Jet Spinner, in the Nl zone only at an input pressure of about 105-110 pounds per square inch, significantly low hairiness is achieved. In still another aspect of the invention, the withdrawal angle of the yarn from the air jet nozzle is controlled to be approximately 30 degrees from the axis of the nozzle. In addition to reducing the hairiness of the yarn, the air stream in the air jet nozzle significantly reduced and stripped pepper trash from the yarn surface, thus producing a cleaner yarn as well as a less hairy yarn. Thus, an overall objective of this invention is to wind ring spun yarn without causing major hairiness increases in addition to removal of impurities. Brief Description of the Drawings In the drawings: Fig. 1 is a diagrammatic representation of a prior art air jet spinning system which uses two air jet nozzles, suitable for practicing the invention and which formed the basis for experimental studies concerning the invention; Fig. 2 is a diagrammatic representation of the method and apparatus of the invention using a conventional air jet nozzle; Fig. 3 is a graph of hairs per meter for various winder configurations, showing the changes in hairiness according to the invention for a 35/1 combed cotton application; Fig. 4 is a graph of hairs per meter for various winder configurations, similar to Fig. 3, showing the changes in hairiness according to the invention for a 35/1 50/50 polyester-cotton mixture; Fig. 5 is a plot of hairs per meter as a function of pressure for the yarn in Fig. 3; Fig. 6 is a plot of hairs per meter as a function of pressure for the yarn of Fig. 4; Fig. 7 is a diagrammatic representation of a modified air jet nozzle as previously shown in Fig. 1; and Fig. 8 is a plot showing improved contaminant removal. Detailed Description of the Preferred Embodiment The main features of the invention were confirmed using a conventional air jet spinner currently available from Murata Kikai K.K. in Japan. A Murata Model 802 air jet spinner was available, a portion of which is shown in Fig. 1. There, diagrammatically, spun yarn is manufactured from a sliver 22 drafted to a desired thickness by back rollers 23, middle rollers 24, and front rollers 25 to be introduced as a staple fiber bundle through a nozzle 26 having a first fluid swirling nozzle Nl and a second fluid swirling nozzle N2 to be converted into a spun yarn 15 drawn out by a delivery roller assembly and wound up by a winding unit (not shown) . The reference letter p designates the air exhaust port between Nl and N2. Reference may be made to U.S. Pat. No. 4,497,167 for the details of such a unit, and the disclosure of that document is incorporated by reference to simplify a discussion of the available equipment used to verify the advantages of the invention. As seen in Fig. 1, the nozzle 26 has two zones Nl, N2. When spinning yarn as intended with the equipment, the nozzle Nl imparts a counterclockwise air vortex when viewed from downstream of the yarn 15, while the nozzle N2 imparts a clockwise air vortex. In this equipment, the air vortex is approximately 300,000 revolutions per minute, as established by the manufacturer. For purposes of verifying the features of the invention, the test winding machinery was run under a constant yarn tension of 35 grams at 900 meters per minute speed. In Fig. 2, the invention is illustrated diagrammatically and denoted by the reference numeral 10. Such a nozzle generally has a fleece separator zone 12, a housing 14 incorporating a nozzle, and a compressed air input 16. For normal operation as an air jet nozzle, the yarn passes through the nozzle in the direction of the arrow denoted by the reference letter a. Thus, when operating as an air jet nozzle, yarn passes from a front roller to a normal inlet 11 of the nozzle 10, through the fleece separator zone 12, past a twist point located in the nozzle, and to a normal outlet 13. In accordance with the invention, spun yarn designated generally by the reference numeral 15 is provided to the nozzle 10 wherein its hairiness is reduced over normally wound spun yarn. Preferably, the spun yarn 15 is provided to the normal outlet 13 acting as an inlet for the spun yarn, and passes through the nozzle 10 in direction of the arrow designated by reference letter c opposite to that of normal operation, to exit from the nozzle 10 at the normal inlet 11. According to the invention, the angle of the exiting spun yarn is controlled relative to the axis of the nozzle 10, preferably to about 30 degrees, as indicated by reference letter b. While the foregoing indicates the preferred embodiment of the invention conceptually, it is not believed necessary to pass the yarn in a reverse direction through the air jet nozzle if the twist direction of the spun yarn is opposite to the conventional right hand twist. When using the equipment noted in Fig. 2, experimental variables were: (1) the direction of yarn movement through he nozzle, either in a normal direction, as shown in Fig. 1, or in a reversed direction, as indicated by the arrow in Fig. 2; (2) the nozzle segment used, i.e. either Nl and N2 in combination, or Nl alone, or N2 alone; and (3) input air pressure. These parameters are summarized in Table 1 for the plot of data shown in Fig. 3 and in Table 2 for the plot of data shown in Fig. 4. TABLE l.TEST DATA FOR 35/1 COMBED COTTON (Corresponds to Figure 3.) CONFIGURATION NUMBER 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 TABLE 2. TEST DATA FOR 35/1 50/50 POLYESTER/COTTON (Corresponds to Figure 4.) CONFIGURATION NUMBER 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 All yarn hairiness testing described herein was executed on the bench model unit from Shirley Developments Ltd. of Stockport, England. The test unit was set to detect hair fibers that protruded at least 3 mm beyond the yarn surface. The data plotted in Fig. 3 relate to 35/1 combed cotton. Of the 21 test conditions noted in Table 1, 18 conditions showed reduced hairiness of the test wound yarn compared to the normal wound yarn. When comparing bobbins and wound yarn, condition 18 has a very nearly equal hairiness in hairs/meter at 105 psi for a reverse yarn direction through nozzle Nl. Similarly, the data plotted in Fig. 4 relate to 35/1 50/50 polyester/cotton (PC) yarn wound at 900 ypm at a tension of 35 grams. Note that in the normal condition, the bobbin hairiness for a 300 m. sample was 4.81, while the wound yarn hairiness for a 200 m. sample was 14.88. Of the 21 conditions plotted in Fig. 4, 18 - 10 - showed reduced hairiness of the test wound yarn compared to the normal wound yarn. Indeed, condition 18 shows a very nearly equal hairiness in hairs/meter at 105 psi for a reverse yarn direction through nozzle Nl. Randomly selected yarns were also wound using the Murata air jet nozzle with similarly dramatic results. In each case, the yarn wound with the Murata jet nozzle showed reduced hairiness over the wound yarn for 31/1 carded cotton; 48.5/1 65/35 PC; 31/1 carded cotton; 35/1 combed cotton; and 15/1 polyester/ rayon for various representative conditions. Figs. 5 and 6 show hairiness reduction as a function of pressure for reverse yarn passage through nozzle Nl for the yarns of Figs. 3 and 4. These data preliminarily indicate an improved result for higher pressures. Figure 7 concerns what we have called "revised Nl". Revised Nl is simply the Nl nozzle portion removed from the N2 nozzle portion. Revised Nl was constructed with the objective of allowing a larger volume of air to contact the yarn, thereby allowing improved removal of contamination (Volumetric air flow through Nl is increased when Nl is separated from N2) . In Figure 7, 5 = supply yarn 6 = compressed air inlet y = direction of yarn withdrawal x = angle of yarn withdrawal relative to Nl axis In addition to the reduction in the yarn hairiness demonstrated by the test data indicated above, it was observed that the air stream in the Nl nozzle stripped away pepper trash from the yarn surface. Therefore, the wound yarn was significantly cleaner and less hairy and those results were apparent regardless of yarn count or blend. Reference is made to Fig. 8 for showing a plot of trash removal effectiveness for the revised Nl approach relative to normal wound techniques or techniques involving an Nl nozzle using a standard open or closed port relative to 20/1 65/35 PC yarn. The present contamination removal brought about by the methods of the present invention indicate the superior cleaning ability when using the present invention. The foregoing description of the invention demonstrates that the surface characteristics of spun yarn, and especially the hairiness of spun yarns can be markedly reduced over that of similar wound spun yarn by passing the spun yarn through an air jet nozzle. The foregoing also demonstrates a new use for existing apparatus in altering surface" characteristics of spun yarn using an air jet nozzle. With the Nl nozzle configured specifically for trash removal cleaning is roughly twice that of normal winding or any other nozzle configuration. For example, although the experimentation described herein utilizes an existing Murata air jet nozzle, it is not to be impled that other nozzles would not produce the same or even better effects in the final yarn. While this invention has been described in conjunction with a specific apparatus, it is apparent that the invention encompasses many alternative , modifications and variations which will be apparent to those skilled in the art. Accordingly, it *is intended to embrace all alternatives, modifications and variation that fall within the scope of the appended claims.

Claims: WHAT IS CLAIMED IS: 1. A method comprising: providing a length of spun yarn; and passing said spun yarn through an air jet nozzle in a predetermined direction and at a predetermined air pressure to alter the physical surface characteristic of said spun yarn. 2. The method as set forth in claim 1 wherein said physical surface characteristic of said spun yarn which is altered is the hairiness of the yarn. 3. The method as set forth in claim 2 where the hairiness of spun yarn subjected to said passing step is altered compared to the hairiness of normally wound yarn from the same bobbin. 4. The method as set forth in claim 3 wherein said air jet nozzle comprises a portion of a conventional air jet spinning machine. 5. The method as set forth in claim 4 wherein said air jet nozzle includes a first nozzle Nl and a second nozzle N2, wherein said air jet nozzle normally passes yarn through said first and second nozzles in a normal direction, wherein the step of passing includes at least one of the following conditions: (a) air pressure in nozzle N2 only and yarn passage in a normal direction through said aid jet nozzle; (b) air pressure in nozzle N2 only and yarn passage in a reverse direction opposite to said normal direction through said nozzle; (c) air pressure in nozzles Nl and N2 and yarn passage in said normal direction; (d) air pressure in nozzles Nl and N2 and yarn passage in said reverse direction; (e) air pressure in nozzle Nl only and yarn passage in said normal direction; or (f) air pressure in nozzle Nl only and yarn passage in said reverse direction. 6. The method as set forth in claim 1 wherein the exit angle of said spun yarn from said nozzle is controlled within a range of 0 to about 30 degrees relative to the axial direction at the exit from said air jet nozzle. 7. A new use for an air jet spinner nozzle, comprising the steps of: providing a length of spun yarn; and passing said length of spun yarn through said air jet nozzle to alter its physical surface characteristics. 8. The new use set forth in claim 6 wherein the physical surface characteristic which are altered are hairiness and cleanliness. 9. The new use as set forth in claim 7 wherein the hairiness is reduced as compared to normally wound spun yarn from the same bobbin. 10. The new use as set forth in claim 6 further including the step of controlling the exit angle of said spun yarn from said air jet to within a range of 0 to about 30 degrees relative to the axis of said nozzle. 11. A spun yarn having been subjected to passage through an air jet nozzle to alter its surface characteristics after spinning. 12. A method comprising: providing a length of spun yarn; and passing said spun yarn through an air jet nozzle in a predetermined direction and at a predetermined air pressure to alter the physical surface characteristics of said spun yarn while removing loose fiber and contamination.

Inventors: ELLIS THOMAS MARTIN, FEIL RALPH WITTEN, ELLIS, THOMAS, MARTIN, FEIL, RALPH, WITTEN
Applicants: INST TEXTILE TECH, INSTITUTE OF TEXTILE TECHNOLOGY
Application year: 1990
Main classification: D01H13
IPC codes: D01H13, D02G3, D02J1, D02J3, D02J7