US 3387447 A
Description (OCR text may contain errors)
June 11, 1968 TRAMMELL ET AL 3,387,447
TRAVELER RINGS Filed Dec. 27. 1965 INVENTORS JOHN A. MANNING, JR. HARLAN M. TRAMMELL WADE J. TRUESDALE 8% zzam/ United States Patent 0 3,387,447 TRAVELER RINGS Harlan M. Trannnell and Wade J. Truesdale, Rock Hill,
S.C., and John A. Manning, Jr., Charlotte, N.C., assignors to Celanese Corporation of America, New York,
N.Y., a corporation of Delaware Filed Dec. 27, 1965, Ser. No. 516,389 6 Claims. (Cl. 57--119) This invention relates to improved twister or traveler rings such as are used on spinning and twisting frames in the textile industry. More specifically, it relates to improved plastic twister or traveler rings containing fluorocarbon resin.
In conventional spinning and twisting operations a plurality of spindles are arranged in a row on a frame beneath a vertically reciprocated rail. The rail supports a plurality of twister or traveler rings, one for each spindle, with said rings arranged to be reciprocated with the rail along the length of the spindle associated with the particular ring. A small, light weight traveler or guide is arranged to freely move about the ring. The traveler therefore rotates about the spindle so that a body of fibers or filaments or yarn or the like engaged by the traveler as it passes to and is wound on a bobbin supported on the spindle is twisted.
Although the traveler is usually metallic, it may also be made of plastic as is disclosed, tag, in United States Patent 3,134,219 and in copending application Ser. No. 501,330 to Karl H. Backhaus et al., filed on Oct. 22, 1965.
Traveler or twister rings are commonly made of metal, however, various and numerous disadvantages presented by such ring material have created considerable research and development activity to find a suitable substitute material.
A primary disadvantage of metal traveler rings is that they necessarily need be lubricated. Lubrication has as basic purpose the reduction of friction between the ring and traveler so as to decrease the heat generated thereby which is the direct cause of wear of both the ring and traveler. Thus, the main purpose of lubricating metal rings is to prolong the life of the ring and traveler, i.e., to obtain maximum wear life. Another reason for lubricating metal traveler rings is to reduce ring to traveler friction in order to lower the tension on the yarn being twisted. Reduction in ring to traveler friction thus allows for higher traveler and spindle speeds because spindle speed is limited by the upper speed limit of the traveler, without exceeding the permissible yarn tension.
Tensions on running synthetic" or man-made textile yarns in twisting operations should not exceed 10r-15% of the average breaking strength of the yarn and should be as much lower as is permissible without producing packages that are too soft or contain uneconomical amounts of yarn. Moreover, tension must be considered in building a satisfactory yarn package in order to prevent bulging at the ends or the elimination of a concave or convex surface. As is well known, variations in tension in filament yarns can cause such quality problems as warp streaks, filling bands, barr, or quill functions in finished fabrics. It need hardly be mentioned that excessive tension on the yarn may result in breaks, machine stoppages, poor quality, etc.
Because metal rings must necessarily be lubricated, as for example, by wicking oil from a reservoir, a mist of oil is created which produces stains and discolorations on the yarn, thus affecting yarn product quality. Moreover, oil splattered or spilled on the floor in the working area makes the floor unclean and unsafe on which to walk.
Even under conditions of good lubrication, fine par- "ice ticles of metal are worn off the metal. ring and metal traveler an become embedded in the lubricant. These embedded metal particles form oxides, carbonates, soaps, etc., of the respective traveler and ring metals, which in turn cause visible stains on the yarn that are very difficult to remove in the ordinary processes of kier-boiling and bleaching. Sometimes the stains cannot be removed at all and the yarn must be disposed of as waste or sold as lower quality yarn.
Due to the tremendously large number of rings used in the textile industry, or in any specific textile spinning operation, traveler ring lubrication presents a considerable maintenance problem. Oil reservoirs must be filled and periodically checked and refilled; also, the rings must be periodically checked to determine if oil is being properly supplied to them. Improper oil supply results in shorter traveler and ring life thus increasing the overall cost of the spinning and twisting operation. Moreover, an improper oil supply results in damaged yarn due to the increased tension on the yarn beacuse of the higher ring to traveler frictional forces.
Lubricant costs, maintenance costs in maintaining proper lubricant supply, cost of removing lubricant stains from yarn, and the profits lost in damaged yarn due to improper tension, and stains which cannot be removed, constitute a considerable portion of the expense involved in the manufacture of textiles.
Other problems and disadvantages presented by metal traveler rings include high initial and replacement costs. Moreover, breakage of metal traveler rings creates considerable disadvantages in their use. Metal traveler rings quite obviously need be of sufficient hardness to present the hardest possible wearing surface to the traveler yet excessive hardness creates brittleness which results in ring fracture during installation or from impact during operation.
Numerous attempts have been made to avoid the disadvantages presented by metal rings by providing rings of materials other than metal. Exemplary of the prior art showing such attempts are United States Patents 2,194,930, 2,796,727, 3,056,251, and 3,148,496, which disclose rings manufactured from glass, nylon, nylon and polyacetal resin, and nylon and polyacetal resin filled with such solid lubricants as molydenum disulfide and graphite, respectively. While traveler rings made from such materials do in many instances represent an improvement over traveler rings made of metal, particularly in the case of nylon and/ or polyacetal rings filled with such solid lubricants as molydenum disulfide and/ or graphite, they have not, however, been totally satisfactory. The vast majority of traveler rings currently in use, even in view of the disadvantages presented, and which are above-mentioned, are of metal. Such substitute ring materials have not, for example, totally eliminated the disadvantages of lubrication presented by the metal rings. Plastic rings currently being used must still be externally lubricated in order to provide maximum wear life for the traveler and traveler ring. Moreover, such rings do not possess such frictional properties over that of metal rings, particularly without lubrication, that allows for greater serviceability such as greater traveler and spindle speeds, twisting of higher denier yarns and higher twists than with comparable sized metal rings. In addition, and as greatly desired in a traveler ring, such materials have not possessed such desirable frictional properties that results in any substantial reduction in yarn tension at a particular machine speed over that of metal rings. As above-mentioned, tension on the yarn being twisted, which tension is greatly influenced by the ringto-traveler friction, is a major limiting factor on machine speeds. As is quite obvious, tension on the yarn must be kept well below the breaking point to avoid broken filaments, strands, etc. Even with ring twisting systems capable of higher running speeds, e.g., above a traveler speed of 7200 f.p.m., such increased speeds are not deemed possible with presently used traveler rings without exceeding permissible tension on the yarn.
It is, therefore, a primary object of this invention to provide an improved traveler ring which will eliminate the necessity of using any external lubricant during operation.
Another object is to provide an improved traveler ring which has a lower coefficient of friction than known traveler rings thus permitting greater machine speeds without exceeding permissible yarn tension.
A further object of this invention is to provide an improved traveler ring of relatively low initial cost and which incurs much less maintenance and replacement cost.
An additional object is to provide an improved traveler ring of greater serviceability than presently used metal and plastic rings, and which is not attendant with the above-mentioned disadvantages.
Other objects of this invention will become more apparent after reading the following detailed description and examining the drawing.
The specific details of a preferred embodiment of our invention, the method of practicing the same, and a proposed traveler ring in accordance with the teachings of this invention will be made most manifest and particularly pointed out in clear, concise, and exact terms in conjunction with the accompanying drawing wherein:
FIGURE 1 is a top plan view of a traveler ring constructed in accordance with the present invention;
FIGURE 2 is a cross-sectional view of the traveler ring shown in FIGURE 1 taken on line 22;
FIGURE 3 is a perspective view of a conventional downtwister in which the improved traveler ring of our invention may be used; and
FIGURE 4 is a top plan view showing the traveler ring in FIGURE 1 fastened to the ring rail in FIGURE 3.
In accordance with the general aspects of our invention, improved traveler rings are provided of a composition comprising a plastic matrix or base modified with or containing fluorocarbon resin.
Such a twister or traveler ring is shown in FIGURE 1 of the drawing. The ring is formed with a weblike annular portion 11 which is adapted for traveler 12 to move around during the twisting operation. As best seen in FIGURE 2, a cross-sectional view of FIGURE 1 taken at the line 22, a reinforcing flange 13 extends outwardly from annular portion 11. Flange 13 has four integral but extended portions 14 which serve as fastening members. Each extended portion contains a hole or perforation 15 in order to mount ring 10 on a ring plate or rail 16 by means of screw fasteners 17 as is shown in FIGURES 3 and 4 of the drawing. Traveler ring 10 is provided with an annular skirt 18 which depend downwardly from reinforcing flange 13. The skirt serves to prevent dust, lint, etc. from accumulating around annular portion 11 which tends to interfere with the movement of traveler 12 around the ring.
Referring now to FIGURE 3 of the drawing, a conventional downtwister mechanism 19 is shown on which the improved traveler ring of this invention may be used. Traveler ring 10 is mounted on ring rail 16 which is reciprocated by conventional means (not hown) by means of screw fasteners 17 as is shown more clearly in FIGURE 4. Yarn 20 (from any suitable source not shown) is directed by conventional guide means (not shown) to takeup rolls 21, 22 and then passes to downtwister 19. The yarn is given a twist as it is wound onto a bobbin located on spindle 23 by passing through traveler guide 12 sliding around on ring 10 mounted on ring rail 16. Spindle 23 is supported by spindle rail 24 and is rotated by belt 25 to collect the yarn on a bobbin on the spindle to form a package of finished yarn 26.
Although four extended portions 14 are shown on traveler ring 10 in FIGURE 1 of the drawing by which the ring is fastened to the ring rail, it is, of course, understood by those skilled in the art that more fastening means may be provided if required, in order to provide a more rigid mounting. It may be necessary to provide 6, 8 or even more extended portions 14, particularly with larger size rings, by which to mount the ring on the ring rail. It may also be found that fewer than the indicated four fastening portions will provide thet desired rigidity. Our invention is not deemed limited by any particular structural configuration, size, etc. The fastening means can take other forms such as, e.g., slotted securing fingers disclosed in United States Patent 3,148,496.
Merely by way of example, the plastic matrix or base material may be polystyrene, nylon, e.g., nylon-66, nylon 6/10, or nylon 6, polyacetal resins such as oxymethylene homopolymers and/or copolymers as described in United tates Patents 2,768,994 and 3,027,352, and the like. The preferred material, polyacetal resins, even in the absence of fluorocarbon resin, has a dynamic coefficient of friction with respect to steel of about 0.1 to 0.3, is abrasion resistant, has a stiffness in excess of about 375,000 p.s.i., for example, about 410,000 p.s.i. determined as set forth in ASTMD-74750, and a Rockwell hardness in excess of about M 80, for example, about M 94 (R 118) determined as set forth in ASTMD875.
The plastic matrix may be from about 5 percent to about 95 percent by weight of the traveler ring composition, and more preferably is from about 75 percent by weight to about 95 percent by weight of the traveler ring composition. (Hereinafter in the specification and claims, percentages are by weight, unless otherwise indicated.)
By way of example, the fluorocarbon resin may be polyperfluoroethylenepropylene, polychlorotrifluoroethylene, and polytetrafluoroethylene. More preferably, however, polytetrafluoroethylene is used in the improve-d plastic traveler of our invention.
The fluorocarbon resin may be from about 95 percent to about 5 percent of the traveler ring composition. More preferably, however, it is from about 25 percent to about 5 percent by weight of the traveler ring composition.
Quite desirably, the fluorocarbon resin is in the form of minute fibers which are uniformly dispersed throughout the matrix and which may be from about 0.05 micron to about microns and even more preferably are from 2-10 microns in diameter. However, the fluorocarbon resin may also be in the form of pellets, floc, powder, flakes, and the like varying from about 0.05 micron to about 100 microns in diameter.
Our invention is further described by the following example which is intended as a particular illustration of the subject invention and not as limitation thereon.
Example A molding composition having about 78 percent poly- -oxymethylene resin and about 22 percent polytetrafluoroethylene resin in the form of minute fibers of about 5-10 microns uniformly dispersed therein is injected into a mold cavity having the shape of the traveler ring shown in FIGURES 1 and 2 of the drawing. The ring is molded according to conventional molding techniques for polyacetal resin. After completion of the molding operation the ring is removed from the mold and the inside surface of the annular we'blike portion 11 is ground in a conventionally known manner with suitable abrasives or the like to provide a smooth surface for the traveler. The finished ring size is 6% inches by 7 inch by inch. It is, of course, understood that the surface of the annular weblike portion 11 can have a matte finish, if such is desired. The thin walls of the ring as shown in FIG- URE 2 provide for relatively good heat dissipation.
Although in the above-given example the ring is formed by injection molding pellets of about 0.100 inch diameter by 0.125 inch length, it is readily apparent to those skilled in that art that such could also be formed by compression molding powder, e.g., of about 60-80 mesh size, according to known techniques for compression molding acetal polymers, or even by casting or by machining by known means from a block or slab of the aforesaid resinous composition.
Uniform dispersion of the polytetrafiucroethylene resin in the matrix material can be obtained by milling together the desired proportions as described, e.g., in United States Patent 3,005,795, after which, it is formed into molding powder or pellets of suitable size according to generally known techniques.
In similar manner, oxymethylene copolymers may be formed into traveler rings with equally good results.
Traveler rings according to the invention are found to have much better self-lubricating properties than known plastic rings. Moreover, our improved traveler rings eliminate the necessity of using any external lubricant during operation.
We have discovered, quite unexpectedly, that ring to traveler friction is reduced to such a degree using the traveler rings of our invention that yarn tension is reduced by as much as 30 percent over that of sintered metal rings Using external lubricant or nylon rings containing molyybdenurn disuliide.
It is, of course, possible to extend the wear life of the traveler ring by prelubrication with known fluorinated hydrocarbon base lubricants. Other prelu'bricants may be used also, e.g., 300 SUS rust and oxidation inhibited turbine quality oil. A very thin film of the fiuorinated hydrocarbon base lubricant is wiped onto the traveler before it is placed in service.
Although polyacetal traveler rings containing polytetrafluoroethylene according to our invention possess suitable flexibility properties for most twisting operations one may desire to decrease the flexibility of such rings under certuin conditions, e.g., where larger size rings and/ or higher machine speeds are used. One way in which this may be accomplished is, of course, by a change in the ring design to provide greater thickness, beefing up the support structure and increasing the number of extended portions and therefore fastening means. However, another and more desirable way in which the stiifness of the traveler ring may be increased is to increase the stiffness ratio, i.e., the modulus of elasticity in tension divided by the density in pounds per cubic inch, to a value of from about to 35, and more preferably about 25. The stiffness ratio is increased by incorporating such additives as aluminum oxide powder, asbestos, glass fibers and flakes, and fibrous colloidal boehmite, to name a few, to the basic composition. ()bviously, the amount of additives or filler added is determined by the stitfness required in the traveler as well as the frictional properties desired therein. Some fillers such as graphite and molybdenum disulfide may serve both to increase the stiffness ratio and the lubricity of the ring. The amount of filler added to increase the stiffness ratio may be between from about 0.25 to about 40 percent based upon the combined weight of the base composition, i.e., the combined weight of the plastic matrix and fluorocarbon resin, and preferably is between from about 10 to about 35 percent.
A principal limitation of known plastic traveler rings in addition to the fact that they need be externally lubricated to ensure maximum Wear life as well as do metal traveler rings lies in the fact that they are relatively poor conductors of heat while at the same time their softening points are relatively low. During a twisting operation a traveler ring becomes subject to very intense localized heat at the point which the traveler contacts the ring. In the case of metal rings, this heat which is developed as a result of the friction between the ring and traveler is fairly rapidly conducted away from the traveler; however, in the case of plastic rings because of the poor conductability of plastic, the heat is conducted away much less rapidly. it is this heat which reduces the wear life of the ring or traveler, or both. In order to provide a more heat conductive ring according to our invention, heat conducting material such as bronze or copper powder or graphite particles may be included in amounts from about 20 to 30 percent based upon the combined weight of matrix or base material and fluorocarbon resin. Preferably, such material may be between from about 26 to 28 percent. Particles added to provide better heat conductivity may also tend to reduce any static electricity accumulated on the ring, thereby reducing dust, lint, etc.; accumulation, which as before mentioned, may aiiect traveler operation, as well as yarn quality, provided, of course, that such ring is properly ground.
in summary, it is mentioned that traveler rings of the present invention present a number of advantages. A major advantage is the elimination of external lubrication. This represents a considerable monetary savings; there is relatively little maintenance cost, and no stains are produced on the yarn. A second advantage is a much lower traveler to ring coefiicient of friction which results in an unexpectedly high decrease in yarn tension. Such decrease ring to traveler friction provi es for increased service-ability, i.e., higher machine speeds, twisting of higher denier yarns and a greater denier range for a particular ring size, as well as increased twist.
It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of our invention.
Having described our invention, what we desire to secure by Letters Patent is:
11. Traveler ring of a composition comprising a matrix or about 95 to percent polyacetal resin and from about 5 to 25 percent particulate polytetrafluoroethylene resin.
2. Traveler ring according to claim 1 wherein about 78 percent by weight of the ring composition is polyacetal resin and about 22 percent by weight is polytetrafiuoroethylene resin.
3. Traveler ring such as is claimed in claim 2 wherein the polyacetal resin is polyoxymethylene.
l. Traveler ring such as claimed in claim 3 wherein the polytetratluoroethylene is uniformly dispersed.
5. Traveler ring according to claim 1 including from about 0.25 to about 40 percent of a material selected from the group consisting of aluminum oxide, asbestos, glass fibers and flakes, and fibrous colloidal boehmlte, based upon the combined weight of polyacetal resin and polytetrafiuoroethylene resin.
6. Traveler ring according to claim 5 additionally including from about 20 to 30 percent of the combined weight of polyacetal resin and polytctrafiuoroethylene resin of a material selected from the class of bronze powder, copper powder, and graphite particles.
References Cited UNITED STATES PATENTS 2,796,727 6/1957 Katerman 57-119 2,831,313 4/1958 Burns et al. 571 19 3,122,384 2/1964 Lauenberger. 3,148,234 9/1964 Boyer 260-900 3,148,496 9/1964 Kight 57-119 JOHN PETRAKES, Primary Examiner.