US3063293A

US3063293A - Method and apparatus for measuring twist

Info

Publication number: US3063293A
Application number: US810436A
Authority: US
Inventors: George H Hutchens; William L Duncan
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1959-05-01
Filing date: 1959-05-01
Publication date: 1962-11-13
Anticipated expiration: 1979-11-13
Also published as: BE589929A

Description

Nov. 13, 1962 G. H. HUTCHENS ETAL 3,063,293

' METHOD AND APPARATUS FOR MEASURING TWIST Filed May 1, 1959 2 Sheets-Sheet 1 Nov. 13, 1962 G. H. HUTCHENS ETAL 3,063,293

METHOD AND APPARATUS FOR MEASURING TWIST Filed May 1, 1959 2 Sheets-Sheet 2 AMPLIFIER AND F CONTROL M56 cmcunnv United States Patent 3,0633% METHOD AND APPARATUS FOR MEASURENG TWIST George H. Hutchens and William L. Duncan, Wayneshero, Va, assignors to E. l. du Pont de Nemours and Company, Wilmington, Del, a corporation of Delaware Filed May 1, 195%, Ser. No. 810,436 9 Claims. (Cl. 73-160) This invention relates to the production of strands from textile fibers and, more particularly, to the measurement of twist in a continuously advancing strand.

In most textile and industrial applications, natural and/ or synthetic fibers are usually employed in the form of'a twisted strand, with the degree and type of twist depending on the ultimate use of the strand. The term strand, as used herein, is intended to include either a regularly twisted or a false twisted monofilament, a filament yarn or a staple yarn, as well as the multi-ply yarns, threads, ropes or cords produced therefrom. The twist may be about the longitudinal axis of a monofilament strand or may follow a helical path as in a multiply strand. The direction of twist is the same along the entire length of a regularly twisted strand and oscillates either in a random fashion or in a carefully controlled manner in a false twisted strand.

Known devices for measuring the amount of twist in a continuously advancing strand are useful only in monitoring highly twisted cords containing at least two twisted plies or, if suitable for measuring the twist in a single ply, do not function accurately on false twisted strands or on yarns having a fuzzy surface. Furthermore, such known devices generally require extremely critical mechanical orientation of the strand being measured and equally critical adjustments and synchronization of the device according to the type of strand being measured. In these devices, the means for indicating the degree of twist is not such as to permit other than a direct visual observation.

The most important object of the present invention is to provide a method and apparatus for measuring the twist in a continuously advancing strand.

Another important object is the provision of a method and apparatus for measuring twist in either a regularly twisted or a false twisted strand.

A further object is to provide an apparatus for measuring both the extent and direction of twist in an advancing strand without altering any of its physical properties which apparatus includes means for indicating the degree of twist instrumentally.

With these and other objects in view, the monitoring apparatus of the present invention comprises generally a frame on which is situated a member having a smooth surface over which the advancing strand passes. As the strand passes over the surface, it tends to follow the twist therein and to traverse the surface in the direction of twist. The apparatus further includes a means responsive to the traversing tendency of the strand for detecting both the extent and direction of twist. The method of the invention involves the steps of orienting a length of an advancing strand, passing the oriented length over a smooth surface, and measuring traverse of the strand away from a linear path of travel over the surface as 3,053,2h3i Patented Nov. 13., 1962 an indication of the extent and direction of twist in the strand.

The method and apparatus will be described more fully hereinafter, with reference to the accompanying drawings, wherein:

FIGURE 1 is a side view of a preferred embodiment of the monitoring apparatus of the present invention; and

FIG. 2 is an exploded view showing the details of the twist indicating mechanism of FIG. 1.

In the apparatus embodiment chosen for illustration, a frame 10 provides support for a package 12 from which a strand 14 is led through a pigtail guide 16 to a tension device 18. Strand 14 travels from tension device 13 through a first reference guide 20, around a cylindrical rod 22, back through a second reference guide 24 and around a guide wheel 26. Rod 22 is the terminal end of a member 23 which is mounted on frame 10. In a constant speed feed system, which also functions to maintain uniform tension on the strand 14, the latter makes several passes around a spacing idler 3d and a feed pully 32 which is driven by a motor 34. The strand passes from the feed system through a guide 28 to a point of ultimate use. Although the strand source illustrated herein is the package 12, it is apparent that the monitoring apparatus of the present invention could as well be fed directly in a continuous process.

After leaving rod 22, the strand passes in close proximity to a follower 38 which forms part of a means for detecting and indicating traversing motion of the strand across rod 22. As shown more fully in FIG. 2, the detecting and indicating means includes an elongated detection element 40 which is pivoted on a jeweled bearing 42 in a casing 53. Element 4t? and follower 38 thus comprise a low friction, low inertia pointer having the spaced portions of follower 33 in bridging relationship to the lower reach of strand 14. Also mounted on the element 44 is a shutter 44 which registers with and eclipses a portion of an aperture 4a in plate 48 when strand 14 is traveling the shortest path between aligned

guides

20 and 24. Movement of the shutter 44 in either direction varies the amount of light passing from lamp 50 through aperture 46 to a measuring photoelectric cell 52 which is coupled by wires 54 to amplifier and control circuitry 56 from which a signal corresponding to the position of shutter 44 may be passed to a suitable recording, control or visual indication instrument. This signal is proportional to the extent of traverse and also indicative of the traverse direction.

In operation, the advancing strand will assume a posi tion on rod 22 which is the resultant of the forces acting thereon. In passing between tension device 18 and feed pully 32, there is a linear force exerted on the strand which tends to position it along the shortest path of travel between the aligned

reference guides

20 and 24. In passing around rod 22, a lateral force is exerted by the tendency of the strand to follow the twist therein which of aperture 46 which is opened for the passage of light to cell 52 wherein a signal is generated and passed, through circuitry 56, to a potentiometer or other suitable means for recording its amplitude either permanently or temporarily. When the yarn is in the zero twist position, the photo-electric detection system is in a balanced condition, i.e., the shutter 44 is in a position leaving approximately half the aperture 46 open. The resulting output of cell 52 is balanced out by adjusting the shutter 51 to provide an equal amount of light to compensating photo-cell 52', which is coupled by wires 54 to the control circuitry 56. Accordingly, a positive or negative output from the combined photo-cell system corresponds to movement of the yarn from the zero twist position.

In a continuous process, the signal from cell 52 could be used to regulate automatically the yarn-twisting mechanism to thereby minimize fluctuations in twist. The nature of the surface of cylindrical rod 22 has an important effect on the operational efliciency of the process. Among the suitable materials which will provide low coefficient of friction between the surface of rod 22 and the advancing strand are satin finish steel, chrome plated steel, glass and Al Si Mag, an aluminum magnesium silicate ceramic. Although a straight cylindrical rod substantially normal to the line of advance of the strand has been illustrated, other intercept angles may be used and the use of curved bars is also practicable. The amount of tension in the advancing strand should be maintained at a minimum consistent with satisfactory operation. With false twisted strands, high tension not only reduces the traverse distance but may also pull out the false twist before it can be measured.

The method of the present invention involves the steps of advancing a strand continuously along its axis, orienting a length of the advancing strand, passing that length over a smooth surface, and measuring the departure or traverse of the strand away from its shortest possible path of travel over the surface. The advancing step may follow the spinning and twisting steps in a continuous process or may be accomplished separately, as shown in FIG. 1. The only requirement for the orienting or stabilizing step is that the strand advance linearly between two points, i.e., that a length be isolated. The passing step may be accomplished as described in connection with the apparatus or in a number of other ways. For example, an operator could exert a slight tension by causing the strand to pass over his finger. Similarly, the measuring step may be accomplished in a number of ways, whether it be instrumentally as described in connection with the apparatus; by using a suitable electronic or photo-electric cell position detection system; by restraining lateral movement of the strand and measuring the restraining force with a suitable strain gage; by visual observation of a scale mounted proximal to rod 22; or with a ruler as the strand traverses a particular smooth surface.

In an actual test of the instant method and apparatus, a continuous filament cellulose acetate yarn (150 denier, 40 filaments) was false twisted for successive lengths at 1, 1.6, 2.7 and 3.3 maximum turns per inch and tested at a tension of 1 gram and a speed of 100 yards per minute, using an Al Si Mag rod /8 inch in diameter. Yarn traverse on the rod was converted to an equivalent electrical signal by the detecting and indicating mechanism shown in FIG. 2. The signal was delivered to a millivolt recording potentiometer, with the results indicating a resolution of $0.2 turn per inch or an accuracy of 5%. In another test, continuous filament nylon yarn (150 denier, 40 filaments) was twisted for successive lengths at zero twist, 1 turn per inch 8 twist, and 0.75 turn per inch 2 twist and tested at a tension of 1 gram and a speed of 100 yards per minute, using an Al Si Mag rod /2 inch in diameter. The sample recordings indicated an obtained precision of better than 0.1 turn per inch. In both instances, the yarn appeared unchanged after testing and a second testing yielded the same results, indicating that the testing method does not adversely affect product quality.

Other advantages inherent in the practice of this invention will occur readily to those skilled in the art and, accordingly, its extent is intended to be limited only by the scope of the appended claims.

We claim:

1. An apparatus for measuring twist in a continuously advancing tensioned strand, said apparatus comprising: a support frame; a pair of aligned, vertically spaced strand guides on said frame; a member on said frame and spaced from said guides, said member having a smooth cylindrical surface around which the strand passes between the guides; an elongated element having a strand-following device thereon; and means pivotally mounting the element on the frame for swinging movement of the device with the strand as the latter tends to follow the twist therein and to thereby traverse said surface.

2. The apparatus of claim 1 wherein is provided an indicator mechanism coupled with said element for indicating the extent and direction of the traversing motion.

3. The apparatus of claim 2 wherein said indicator mechanism includes a light source, a photoelectric cell, an apertured plate between the source and cell, and a shutter connected to said element, said shutter being positioned between the plate and said source.

4. An apparatus for monitoring the twist in a continuously advancing tensioned yarn-end, said apparatus comprising: a support frame; a pair of aligned, spaced yarn guides on said frame; an elongated cylindrical rod projecting out from the frame in spaced relationship to the guides and with its axis substantially normal to the axis of the advancing yarn-end, said rod having a smooth surface over which the yarn-end passes between the guides; and means coupled with the yarn-end for detecting and indicating lateral movement of the yarn-end responsive to the twist therein.

5. A method of measuring the twist in a continuously advancing tensioned strand comprising the steps of: orienting a length of the advancing strand; passing the oriented length over an elongated member provided with a smooth surface, in intersecting relationship with and at an appreciable angle with respect to the axis of the member; and measuring traverse of the strand on said surface away from its normal path of travel as an indication of the extent and direction of twist in the strand.

6. A method of checking the twist in a continuously advancing tensioned yarn-end comprising the steps of: orienting a length of the advancing yarn-end; diverting the path of said yarn-end in said length by passing it around a smooth cylindrical surface; and measuring the extent and direction of yarn traverse on said surface as the yarn tends to follow the twist therein in passing over the surface.

7. An apparatus for measuring twist in a continuously and axially advancing tensioned strand, said apparatus comprising: a support; an elongated member on the support, said member having a smooth surface over which the strand passes at an appreciable angle with respect to the axis of the member; means on the support for detecting lateral movement of the strand as it tends to follow the twist therein in passing over said surface; and indicator means coupled with the detecting means for indicating the direction and extent of the movement.

8. An apparatus for measuring twist in a continuously advancing tensioned strand, said apparatus comprising: a support; an elongated member on the support, said member being provided with a smooth surface over which the strand passes axially and at an appreciable angle with the axis of the member; means on the support for detecting twist in the strand, said means including an element positioned adjacent the strand for engagement therewith as the advancing strand tends to follow the twist therein and thereby tends to traverse said surface; and indicator means coupled with said element for indicating the extent and direction of the strands tendencies to -folthe surface; and indicator means coupled with the detectlow the twist therein and traverse said surface. ing means for indicating the extent and direction of its 9. An apparatus for measuring twist in a continuously movement.

advancing tensioned strand, said apparatus comprising: a

support frame; a pair of spaced-apart strand guides on the 5 References Cited in the file Of this Patent frame; an elongated member on the frame having 21 UNITED STATES PATENTS smooth surface over which the strand passes axially and at an appreciable angle with the axis of the member in its 2759324 Dean 1956 travel between the guides; means coupled with the strand FOREIGN PATENTS for detecting lateral movement of the advancing strand 10 107,779 Sweden June 29, 1943 as it tends to follow the twist therein in its travel over