US2293955A - Winding strandular material - Google Patents

Description

A08- 25. 1942. J. D. VAN DOBBENBURGH WINDING STRNDULR MATERIAL Filed May 28. 1940 gmc/whom Ulllem J. D. Uan Dobbenburqh,

Patented Aug. 25, 1942 WINDING STRANDULAR MATERIAL Willem J. D. van Dobbenburgh, Enka, N. C., as-

signor to American Enka Corporation, Enka, N. C., a corporation of Delaware Application May 28, 1940, Serial No. 337,701

3 Claims. (Cl. 57-62) This invention relates to the twisting of threads and more particularly to methods lof and apparatus for eliminating irregularities normally occurring in threads of synthetic'character in their passage between a supply package and a draw-o device in an 11p-stroke twisting machine.

In the twisting of thread on an upward twister, the thread, after being withdrawn overhead from a rapidly rotating supply bobbin, is passed through anfadjacent pigtail guide yand collected upon a take-up spool. The thread in this manner receives a denite number of turns per inch, in part depending upon the rate at which it is withdrawn. The rapid/.rotation of the supply bobbin causes the thread to balloon outwardly therefrom between the point of. delivery of the thread from the bobbin and the pigtail guide, said guide serving to confine the thread'at that point.

- While a twisting machine of the type discussed above is quite satisfactory as regards -most of the aspects of its operation, it has been noted that rayon filaments twisted thereon to form a thread are frequently impaired during the twisting loperation, such impairment involving4 the production of irregularities in the thread known to the art as loops and corkscrews. Of course, the presence o! such imperfections in the thread seriously impairs the uniformity thereof and, as a result, the product is rendered unsatisfactory for many industrial and textile purposes.

While the exact reason for the production of irregularities in thread twisted according to conventional methods involving the use of vknown machinery is-not fully understood, it is-believed that the centrifugal force set up by the rapid rotation of the supply bobbin causes an initial displacement of individual. filaments in the thread layers in the package. This initial displacement is more pronounced in the outer layers of the package because after the necessary processing steps., the outer layers are loose and softer than the inner layers. When the filaments are drawn of! at a high rate of speed they become even more disturbed and loosened as they have vand also because as the diameter of the package decreases, the centrifugal force decreases.

While such irregularities are likely to be produced in 'the twisting of any threads they are no opportunity to become realigned and thus are entangled with other layers of thread. In some instances, sticky substances remaining in the thread from previous treating steps may cause laments to adhere to the thread package, the result being that certain laments are stretched and become looped about the thread mass thereby producing undesirable irregularities. The loop and corkscrew formation is not as evident particularly noticeable in the twisting of rayon threads, inasmuch as rayon threads a're made up of large numbers of individual filaments of a delicate character, which, prior to twisting, are in substantially parallel relation to each other. Heretofore, such defects as loops andcorkscrews have been regarded'as normal imperfections in rayon threads.

A number of eilorts have been made to overcome these dilculties encountered in the twisting of rayon threads. For example, friction members have been interposed'in the path of the thread intermediate the supply bobbin and the take-up device, with a view to at least in part eliminating the occurrence of loops and corkscrews by imparting a drag on the thread. Such devices may cause localized overstretching, however, and thereby merely effect the substitution of one type of non-uniformity for another. It has been found that by slowing down 'the entire twisting operation the formation of loops and corkscrews can be avoided. However, such a method is not entirely satisfactory because its employment so retards :the rate of production of thread as to cause a serious increase in the cost'of operation of the manufacturing plant. It it therefore an object of this invention to provide a process wherein the thread constituting.

a complete package of rayon may be twisted at a high average speed without the formation of irregularities therein while the application of mechanical braking means to the thread is entirely avoided.

It has been discovered that a high average winding speed may be maintained without the formation of loops and corkscrews by effecting the twisting of Vdifferent portions of the yarn con..

stituting the package at diierent speeds, lower i i speeds being employed as regards portions of the thread on the package which have been found to be more susceptible to injury than other portions.

It is further contemplated by this invention to provide a method and apparatus for twisting yarn at varying linear speeds whereby to maintain maximum eiiiciency of operation in ccnjunction with the production of a superior product.

Other objects and advantages of this invention will be apparent from a consideration of the foilowing detailed description of a preferred embodiment thereof in conjunction with the accompanying drawing wherein:

Figure 1 is a diagrammatic view in side elevation of a thread twisting unit; and

Figure 2 is a view in front elevation of the unit shown in Figure 1.

It will be understood that the twisting assembly shown in Figures 1 and 2 may consitute but a single unit of a machine comprised of a large number of such units intended for simultaneous operation and adapted for the concurrent twisting of thread from a large number of supply packages. Referring in greater detail to the drawings, the unit disclosed consists of a thread package I0, a pigtal guide II, a traverse mechanism I2, and a draw-off spool I3. The thread is twisted in its passage between package I and draw-off spool I3 as a result of the rapid rotation of the former. This rotation is effected by mounting package I0 on a spindle I4 which is connected to a whorl I5, the cylindrical surface of which contact a belt I6 driven from a source not shown.

The package I0 consists of a large number of convolutions of rayon thread II and, as the package is rapidly rotated, this thread is drawn from the outside of the package upward along the axis,

of rotation thereof through pigtal guide II.to traverse mechanism I2 and onto draw-off spool I3. The draw-off spool is mounted on shaft I8 and is driven by a generally cylindrical roller I9, the cylindrical surface of which initially contacts the surface of the spooland later, as the twisting operation progresses and thread is wound thereon, the roller contacts the wound thread body. Roller I9 is driven through shaft 20 to which it is keyed. Shaft 20 is actuated from a source of power not shown and, according' to conventional practice, the drive for shaft 20 is connected with the drive for belt I6 to maintain a constant speed ratio between the two. It will be understood that adjustment in the ratio between these two drives may be eiected for the purpose of varying the degree of twist imparted to the thread.

Since roller I9 contacts the surface of the thread body wound on draw-off spool I3, shafts I8 and 20 will tend to move apart as succeeding convolutions of wound thread increase the effective radial thickness of spool I3. For this reason shaft I8 is so journalled as to permit vertical movement toward and away from roller I9 while the thread surface on spool I3 maintains continuous contact therewith. As the thread builds up on draw-off spool I3 the speed of rotation of shaft I8 will be somewhat reduced, but because of the surface contact between roller I9 and spool I3 the thread take-up will continuously equal the peripheral speed of roller I9.

The thread, after its passage through pigtal guide II, is laid-up on draw-off spool I3 by a traverse mechanism of conventional form designated by the numeral I2. Traverse mechanism I2 is driven from the same source as roller 9 and, as a consequence, vfill distribute thread onto spool I3 in proportion to the speed at which said spool is v driven. It will be recognized that all of the above described twisting assembly is quite conventional and well known in the art.

As above indicated, package I0 includes a wound body of rayon thread. Packages of this character are ordinarily made up from freshly spun articial filaments which are wound into package form and are thereafter subjected to treatments such as desulphurizing, washing,

bleaching, drying and so forth. It is after these treatments have been completed that the twisting of the thread is accomplished. It has been discovered that the thread constituting a package so prepared and so treated does not react uniformly to twisting. It has been determined that the outer convolutions of thread of a package, normally about 8000 yards or about one-third of the package, cannot be twisted at ordinary speeds without the productionof undesirable loops and corkscrews in the twisted thread. On the other hand, the inner convolutions of yarn constituting approximately two-thirds of a package of rayon thread can be twisted at such speeds, for example, at a linear speed of 33 yards per minute. 'I'his gure is calculated for 6000 spindle revolutions per minute for a twist of 5 turns per inch. With a spindle speed of 6000 revolutions per minute given, the take-up speed will, of course, be different when 6 turnsare inserted instead of 5 turns. A ligure in practical use is 6100 revolutions for 5 or 6 turns. Driving roller I9, having a diameter of 3% inches, is caused 'to rotate at about 99 R. P. M. to produce this linear-speed. It has been further discovered that the initial convolutions ofA yarn, the outer one-third of the package, can be twisted at a spindle speed of 4000 R. P. M. without injury to the thread incident to the occurrence of loops and corkscrews therein. To capitalize on those discoveries, the twisting operation is carried out at two speeds, an initial subnormal speed to avoid the production of loops and corkscrews while the outer convolutions of thread are twisted, followed by the resumption of a normal speed in twistingthe remainder of the thread constituting the package.

While the theory involved in avoiding the formation of irregularities in twisted thread by operating the twister at the speeds indicated above is not fully understood, it is known that this method of operation is quite successful and that the speeds may be modified to a certain extent without injury to the thread. It seems that because of the thickness of the package at the beginning of the twisting operation there is a tendency toward entanglement, while during the later stages" of twisting, when the package is partially depleted; this tendency does not exist.

To eiect the alteration of the twisting speed without interfering with the degree of twist imparted to the thread, a two-speed electric motor is used to drive belt I6, shaft 20 and its rollers I9,

as well as traverse mechanism I2. Alternatively, a motor may be employed wherein the speeds are varied Aover'wide ranges by means of a frequency changer. Since these driven elements are conventionally operated in synchronism their operation at two different speeds will not alter the degree of twist imparted to the yarn but will permit the twisting of the thread constituting the outer one-third of the package at a slower rate to avoid the production of loops and corkscrews while the remainder of the'package may be twisted at a usual speed to promote manufacturing eiilciency.

IA, manually operated switch may be employed to selectively control the speeds of the motor, or lthe switch may be associated with shaft I8 so that upon completion of the radial movement of said shaft in response to the winding of approximately one-third of a package on draw-off spool I3, the

motor will be caused to operate at increased of supply packages. Of course, when rayon thread -ls so collected, after twisting, it is apparent that the draw-oil speed and speed of rotation of the bobbin must be reduced during the winding-on of the initial convolutions of each of the packages employed in making up the wound spool. When the thread on more than one package is wound on a single draw-off spool, the switch associated with shaft i8 can be employed only in modiiled form. v y

A manually operated change-speed'transmission has been employed with success to vary the eective speed of the motor as regards thel various units of the twisting assembly instead of the two-speedfmotor described above.

Having now described the invention in its preferred form, it is understood that variations and modiiications may be made therein without departing from the spirit of the inventiomand it is desired that the scope thereofk be limited only by the appended claims.

What is claimed is:

l. A method of twisting succeeding portions of a single rayon thread consisting of a plurality of substantially parallel continuous laments which have been cross wound in package form in radially superposed layers, in the path of travel of the thread from said package to a collecting device whereon it is again wound in package form at such high average spindle speeds thatv the thread balloons radially from, the delivery package due to the centrifugal force generated thereby, comprising, rotating the thread package, drawing off from the outside of said pack-y proximately one-third of the outer radially superposed convolutions of thread are twisted and thereafter resuming a. high draw-oft speed and.

proportionate speed of rotation of the thread package while the remainder of the component thread of the package is twisted and maintaining said high draw-E speed throughout the remainder of unwinding and as all portions of the.

thread adjacent the package axis are thrown oit, whereby the occurrence of irregularities in the thread is avoided.

2. A method of twisting succeeding portions of a single substantially parallel filament rayon thread cross wound into package form which comprises, rotating such a package of such thread at high speed to throw oil succeeding portions of thread radially from the outside of said package to effect progressive reduction in radius of the package by successive removal of cylindrical layers of thread therefrom, drawing said thread as thrown o along the axis of rotation of the package, initially temporarily reducing the drawoiA speed and proportionally the speed of rotation .of the thread package while the outer convolutions of thread are drawn and twisted, and thereafter resuming a high drawoff speed and proportionate speed of rotation of the thread package while the remainder of the package is twisted, the speed of rotation of the package being uniformly high as all portions of thread adjacent the package axis are thrown off.

3. A method'of twisting succeeding portions of a single substantially parallel filament rayon thread cross wound into package form which comprises, rotating such a package of such and proportionate speed of rotation of the thread package while the remainder of the package is twisted, the speed of rotation of the package be,

ing unformlyhigh as all portions of thread,ad

jacent the package axis are thrown off. said initial speed of rotationY of the thread package being at least 4000 revolutions per minute, which speed is maintained for at least the winding of one-thlrd of the package and being inv a ratif of about 2 to 3 with respect tothe speed of rotatation of the thread package while the outer package;

WILLEM: J. D. VAN 'DOBBENBRGI-I.

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