US 3161913 A
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Description (OCR text may contain errors)
1964 c. R. POUND 3,161,913
YARN RELAXING APPARATUS Filed April 19, 1962 2 Sheets-Sheet 1 Dec File
C- R. POUND YARN RELAXING APPARATUS d April 19, 1962 2 Sheets-Sheet 26 a7 as \jiga E20- 8 g 5- E to- 1 l I 1 1 A00 .75 .50 .35 0
69)? kavnzzvxxva a was/1v larva United States Patent Ofiiice 3,1513% Patented Dec. 22, 1964 3,161,913 YARN RELAXENG APPARATUS Claude Russell Pound, Aiken, S.., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed Apr. 19, 1952, Ser. No. 188,675 Claims. (Cl. 18--8) This invention relates generally to the production of nylon filamentary yarn and, more particularly, to an apparatus wherein such yarn structures are drawn to increased length and orientation.
Some of the problems experienced with drawn nylon yarn as a result of its tendency to undergo a gradual lengthwise retraction on standing have been disclosed by Pitzl in US. Patent No. 2,956,330. For example, it has been noted that the differential extent to which filaments are permitted to retract in various locations on a drawtwister package leads to variations in such properties as denier, modulus, break elongation, dyeability and boilolI shrinkage. Such fabrics defects as pirn taper barre have been traced to these property variations; the streakiness may be due either to differences in dye depth, denier variations or irregularities in fabric construction related to variable shrinkage in the warp yarn. Additionally, the compressive forces developed by the gradual retraction of packaged yarn has necessitated the use of high strength package cores. Although the successive drawing, setting and relaxing steps disclosed by Pitzl have proved effective as solutions to these and other problems, they also require the application of heat under closely controlled conditions.
The most important objective of the present invention is to provide for the eifective relaxation of freshly drawn nylon filamentary yarn in a rapid and continuous manner.
Another important object is the provision of apparatus improvements which facilitate the preparation of drawn relaxed nylon filamentary yarn having uniform properties, including a substantially undiminished initial modulus, through their length.
These and other objectives are accomplished without the use of heating, swellin or plasticizing agents by routing freshly drawn yarn to the inner surface of a rotating tube on which surface it is deposited by centrifugal force and stored under substantially zero tension. After sufficient time in the tube to permit relaxation, the deposited yarn is withdrawn continuously, i.e., it is withdrawn at a speed less than that at which it was routed to the tube. This speed differential and residence time in the tube are so related that the extent of relaxation is substantially the same for'successive yarn lengths. After withdrawal, the relaxed yarn is either Wound on a package or forwarded to a coupled process stage.
It the following specification, reference is made to the accompanying drawings wherein:
FIGURE 1 is a schematic representation of a drawtwister installation useful in the practice of the present invention;
FIG. 2 is a sectional view of the relaxing apparatus shown schematically in FIG. 1; and
FIG. 3 is a comparative illustration of retract-ion values for relaxed and unrelaxed yarns.
In the yarn-drawing installation illustrated schematically in FIG. 1, undrawn nylon yarn is withdrawn from package 12, passes through the pigtail guide 14 and is wrapped in multiple wraps about driven feed roll 16 and its associated separator roll 18. Alternatively, as spun yarn can be supplied to guide 14 directly from a spinning machine rather than from package 12. From feed roll 16, the undrawn yarn 10 makes one or more wraps about snubbing pin 20 (Babcock, US. 2,289,232), and is drawn in frictional contact with that pin under the urging of draw roll 22 with its associated separator roll 24. Draw roll 22, of course, has a higher peripheral speed than feed roll 16 whence the yarn is elongated to several times its original length. From separator roll 24, the drawn yarn passes through a rotatably driven relaxing apparatus 26 and guide 28 to a smaller diameter 29 of stepped draw roll 22. Associated with the stepped-down portion 29 of draw roll 22 is a separator roll 30. From there, the relaxed yarn passes through a pigtail guide 32 and is wound onto a tapered twister package 34 by means of a ring 36 and a traveler 38. The tension in the yarn being wound on package 34 is controlled by the weight of the traveler 38.
As best shown in FIG. 2, apparatus 26 includes a stationary tubular member 40 having a yarn inlet guide portion 42 and a yarn-traversing bell portion 44 as its outlet. Bcll portion 44 terminates in a lip having an angularly disposed peripheral edge 45. Tube relaxer 26 also includes an outer tubular member 46 which is rotatably, coaxially mounted on guide portion 42 by hearing 4%, in surrounding relationship to stationary bell portion 44.
The illustrated embodiment is placed in use by routing freshly drawn yarn through guide portion 42 to the inner surface of rotating tubular member 46, stringing-up the apparatus as far as guide 28, holding or tying the free end at guide 28 while permitting a cake 47 of the desired size to accumulate, and then stringing-up rolls 29, 3%, guide 32, traveler 38, etc. The centrifugal forces acting on the yarn as it is deposited on cake 47 are sufficient to advance it continuously from roll 24 through the guide portion 42 of stationary member 46. In exciting member 40, it travels around the peripheral edge 45 of hell portion 44. This angular disposed edge 45 imparts a helix angle to the yarn as it is deposited on cake 47. As a consequence, there is a surplus length of yarn per convolution which facilitates relaxation without yarn entangle- 11161111. Similarly, the centrifugal forces acting on cake 47 are sufficient to prevent twisting and turning of the cake as relaxed yarn is withdrawn from its outer layer through the open end of tubular member 46 by stepped roll 29. The extent to which the substantially zero tension yarn in cake 47 is permitted to relax depends on its residence time in that state, i.e., on the amount of yarn in the cake. Maintenance of that amount, as the process continues, is insured by use of a withdrawal portion 29 stepped down by the same percentage that the drawn yarn is relaxed.
In actual practice, IS-denier nylon filaments have been drawn at a ratio of 4.6, relaxed in an apparatus of the type shown in FIG. 1 and compared with filaments drawn at the same ratio but not relaxed. The roll surface 29 over which the relaxed filaments were withdrawn had an 8% step-down from the roll surface 22 over which they were fed to the tube relaxer. The relaxed yarn had an initial modulus of 31.91 grams/denier and a 24-hour retraction of 0.49% as compared to an initial modulus of 34.7 grams/ denier and a 24-hour retraction of 1.35% for the control yarn. In addition, 24-hour retractions were determined at a number of points throughout the packages on which the two yarns were wound and the values were plotted, giving the curves 48, 50 (FIG. 3) for the control and relaxed yarns, respectively. The uniform low retraction of the tube relaxed yarns is apparent from a comparison of the curves.
Retraction values were determined from yarn samples obtained by stripping representative -150 cm. lengths from successive locations throughout the packages. In making such determinations, sample length was determined immediately after removal from the package and before the yarn had been conditioned after drawing.
The ends of the yarn segment were knotted together, a Weight of about 0.1 g.p.d. was hung on the loop, and the length of this loop measured. Loop length of such loaded samples was also measured after exposure for 24 hours at 75 C., 72% relative humidity. Percent retraction was calculated from the two sets of measurements.
As reported herein, initial modulus is defined as the ratio of change in stress to strain in the first reasonably linear portion of a stress-strain curve. The units employed make the initial modulus numerically equivalent to 100 times the force in grams/ denier required to stretch a sample the first 1%.
Initial modulus is a useful measure of yarn resistance to lengthwise deformation and is highly indicative of yarn behavior during subsequent packaging, on the package and in subsequent textile operations such as twisting, quilling, Weaving, and knitting. Yarn having a high initial modulus is relatively insensitive to tension variations encountered during these operations; conversely, yarn with lower values of initial modulus is noticeably sensitive to such tension variations and forms poorer quality fabrics exhibiting the above mentioned streaks and barr. as also noted above, yarn relaxed in accordance with the present invention has a high retained initial modulus.
The process of this invention is useful in the preparation of spindle-wound packages having a variety of contours, such as bottle bobbins, filling wind bobbins or headed spools and in draw-winding operations where square or tapered shoulder packages of zero twist yarn are wound upon cylindrical cores, using conventional reciprocating traverse means during winding. By employing the present process and apparatus in these operations, it is possible to wind freshly-drawn yarn onto inexpensive disposable paper cores, hitherto impossible because of the compressive forces developed in packages of unrelaxed yarn. By providing a one-Way shipping package in a single operation, large savings are realized, since repackaging prior to shipping becomes unnecessary and the need for extreme strength cores is obviated.
, The process of this invention is especially useful with yarn composed of synthetic linearpolyamides, such as those disclosed by Carothers in US. Patents Nos.
2,071,250 and 2,071,253. The preparation and spinning of these compounds has been disclosed in US. Patents Nos. 2,130,948, 2,163,636 and 2,477,156. Examples of such polyamides are those prepared from suitable diamines and dibasic acids, e.g., from hexamethylene diamine and the passage of yarn therethrough; a second rotatable tubular member mounted coaxially with and in surrounding relationship to said first member adjacent its outlet end: drive means connected to said second member for imparting rotation thereto, said second member being of unitary construction, having a substantially uninterrupted inner surface adapted to receive and carry any accumulation of yarn and being open at one end to permit the withdrawal of yarn therefrom; and means associated with said second member for withdrawing yarn from said accumulation.
2. The apparatus of claim 1 wherein said outlet end has a peripheral edge in a plane disposed at an angle to the axis of said first tubular member.
3. The apparatus of claim 1 wherein said first tubular member is bell-shaped at said outlet end and terminates in a lip having its peripheral edge in a plane disposed at an angle of :less than 90 with respect to the rotational axis of said second tubular member.
4. In combination with a yarn-drawing installation, an apparatus for relaxing drawn yarn, said apparatus comprising: a rotatably driven tubular member having openings at each end thereof; guide means for routing yarn from said installation, through one of said openings, to the interior of said member, the latter being of unitary construction and having a substantially uninterrupted inner surface adapted to receive and carry an accumulation of yarn and means for withdrawing yarn from said accumulation through the other of said openings.
- 5. An apparatus for relaxing drawn filamentary yarn, said apparatus comprising: a tubular member mounted for rotation about its tubular axis, said member having a substantially cylindrical'and uninterrupted inner surface;
drive means connected to said member for imparting within and coaxially of said tubular member, said element having a terminal peripheral edge in a plane disposed at an angle of less than 90 with respect to said tubular axis whereby to traverse yarn back and forth as it accumulates in layers on said surface; and roll means for withdrawing yarn from the outermost layer and advancing it for adipic acids; also comprehended are polyamide's prepared from terminal-amino carboxylic acids, and their amide-forming derivatives, e.g., polycaproarnide from caprolactam. Yarn counts may range from monofilaments to yarn having a large number of filaments.
Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:
1. An apparatus for relaxing yarn, said apparatus comprising: .a first stationary tubular member adapted for packaging.
References Cited in the file of this patent UNITED STATES PATENTS 1,990,617 Sanders et al. Feb. 12, 1935 2,153,823 Byron Apr. 11, 1939 2,304,212 Sowter et a1 Dec. 8, 1942 2,611,923 Hume Sept. 30, 1952 2,786,637 Russell et al Mar. 26, 1957 V FOREIGN PATENTS 570,986 Belgium Sept. 30, 1958