US3452533A - Over-end winding of yarn - Google Patents

Description

United States Patent U.S. Cl. 57156 4 Claims ABSTRACT OF THE DISCLOSURE Patterning in a yarn package, due to e.g. ring-tilt, is reduced by varying the spindle speed at more than one frequency of variation.

The invention concerns improvements in or relating to the over-end winding of yarn.

Over-end winding of yarn, as on the well-known ring spinning machine ,is practised when it is desired to impart a twist to the yarn by the act of winding.

A common instance of such over-end winding is to be found in the drawtwisting of synthetic polymer filaments; and the present invention will be described in relation to such drawtwisting, although it is to be understood that the invention is not limited thereto.

A drawtwister is essentially a downtwister in which are incorporated roll mechanisms for drawing undrawn yarn. Usually, such mechanisms consist of nip rolls rotated at a given speed acting as feed rolls; and a draw roll and separator roll combination, the former roll of which is rotated at the required higher speed to effect the drawing action on the filaments in question. From the draw roll, the drawn filaments proceed in a generally downward direction to a thread guide positioned axially, or nearaxially, of the spindle of a ring and traveller ring spinning mechanism. This thread guide is sometimes known as the balloon guide, as the yarn is ballooned beneath it by virtue of the rotation of the traveller around the ring. The filaments are then wound up on a bobbin mounted on the rotating spindle, by passage around the traveller which is itself rotated around the ring and by reciprocation of the ring, in its rail, tray or other carrier, in the axial direction of the spindle according to the builder motion required for the particular yarn package to be wound on the bobbin.

It is a quite usual artifice to tilt the ring of the ring spinning mechanism in order that the filaments shall be laid on to the bobbin and yarn package in helical coils having a wavy path rather than a flat helical one. An angle of tlit of between 3 and 6 is usual; although an angle even as low as 1 may be selected and will donate an appreciable wave component to the laying-on path of the yarn. Rings are not generally set to a greater degree of accuracy than within /2".

Such ring tilt is at least a major factor predisposing the formation of regions of patterning at certain radii of the package build, owing to the coincidence of adjacent coil loci. The incidence of these various regions of patterning, which patterning is to be avoided both from the technical point of view of package stability and yarn take-01f characteristics and from the point of view of appearance, can be calculated, e.g. by analogue computer, for any given process involving a drawtwisting wind-up; and hence it is possible to so programme the winding conditions that the regions of patterning which normally would occur shall be avoided.

3,452,533 Patented July 1, 1969 An alternative, or concomitant, approach to the reduction or avoidance of patterning, whether from natural or self-induced causes, consists in the rapid variation of one or more of the winding parameters, to bring about a scrambling of the winding conditions throughout the winding, in order continuously to modify the wave-form of the coils of yarn as laid on to the take-up package.

Thus, the spindle speed may be rapidly varied by, say, 10% about the mean value desired; and this rapid variation, or scrambling, of the spindle speed will serve to break up patterning when it occurs at the calculable winding conditions during the formation of the package. Variation takes place in a cyclical manner about the mean spindle speed; and the number of cycles occurring in unit time is termed herein the frequency.

We have found, however, that with one fixed frequency of speed variation for the spindle speed, there is the disadvantage with constant-rate traverse motions that conditions will recur during the winding when the ratio of spindle speed scrambling frequency to traverse frequency is a ratio of small whole numbers such as to lead, of itself, to patterning regions throughout large volumes of the package.

The present invention, therefore, is based on the proposition that mare than one spindle speed scrambling frequency shall be employed during the winding, the choice of frequencies and the programming of their application being effected so as to avoid any ratio of scrambling frequency to traverse frequency during the entire winding which is a ratio of small whole numbers leading of itself to patterning.

The invention comprises a method of winding yarn by over-end winding on to a package with the aid of a rotating spindle and a traversing means, wherein the speed of rotation of the spindle is varied cyclically about mean values thereof selected to be operative at given times during the winding of the package, or about a mean such value maintained constant throughout the winding, and wherein the frequency of such cyclical variation in spindle speed is changed between at least two values during the winding, according to a programme of changes calculated to avoid any value of the ratio of said frequency to the traversing frequency ever being one consisting of small whole numbers (i.e. either of which is less than 5) such as would of itself lead to patterning occurring at given radii of the package during winding.

Whilst it is possible to effect an improvement compared with a single spindle speed variation cycle time by the use of two such cycle times, it is not always possible completely to disperse regions of patterning thereby. This is because, although the shifting of such scrambling frequency has the effect of enabling whole-number ratios of scrambling frequency to traverse frequency to be avoided, nevertheless it also has the effect of changing the width and spacing of regions of patterning caused thereby, making it difificult to so alternate two frequencies that shift from one to the other does not involve a shift into part of a region of patterning.

Hence, it is preferred, according to the invention, to use more than two scrambling frequencies, whereby the chance of programming the shifts so as completely to avoid patterning conditions is greatly enhanced.

The means of programming may take various forms, the exact operation of which may depend on whether the traverse motion of the drawtwisting machine is of a constant-rate or a constant-time variety.

Programming by a general purposes analogue computer is one such means, the computer serving automatically to control the number of changes in spindle speed cycle time occurring during the winding of a full package, by continuously measuring said traverse cycle by electronic means and controlling shifts from one frequency to another so as to avoid the critical ratios of such scrambling frequency to traverse frequency.

The specific method of shifting spindle speed cycle times according to the invention, e.g. by regulation of a servomotor in the spindle driving mechanism, may be combined with other expedients for the avoidance or reduction of patterning in overend wound yarn packages.

Thus, the invention may be combined with other more radical programming of the spindle speed, e.g. whereby regions of patterning due to ring tilt may be avoided. Equally, the invention may be combined with controlled or random variations in traveller speed and with yarn delivery speed.

Whilst the invention is applicable to the winding of yarn packages on all kinds of bobbin or tube, it will be understood that the particular programme to be selected will be affected by the shape of the tube, e.g. as to whether it is frusto-conical or cylindrical.

By way of one example of the invention, the following details are given of a process for drawtwisting 70 denier 30 filament yarn of polyhexamethylene adipamide (nylon 66), at a draw ratio of 3.36 and a drawing speed of 2,300 feet/minute. The yarn was woundup by a ring spinning mechanism with the ring tilted to 3 to the horizontal; and the yarn package was wound with a long-to-short traverse build, constant traverse speed. The spindle speed was programmed so as to reduce from an initial 9,750 r.p.m. to a final speed of 7,350 r.p.m.

In addition to the above programming, a 3-shift rapid variation in spindle speed was programmed on to the spindle drive mechanism by an analogue computer, of an amplitude of of the instant spindle speed, the rate of change of spindle speed (or scrambling frequency) being changed according to a 3-shift rapid variation programme so designed that the shifts in spindle speed occurred when the ratio of scrambling frequency to traverse frequency at one of the scrambling frequencies approached a ratio of small whole numbers, i.e. whole numbers either of which is less than 5.

In a second, but less advantageous example of the invention, 100 denier 34 filament yarn of polyhexamethylene adipamide was wound up at 2646 feet/minute after being drawn on a drawtwisting machine. The yarn was wound-up by a ring spinning mechanism, with the ring tilted to 3 to the horizontal; and the yarn package was wound with a long-to-short traverse build, at a constant traverse speed of 23 inches/minute. The mean spindle speed was maintained constant at 6,850 r.p.m.; and this speed was varied -10% about the mean at two discrete frequencies, and a change was made from one to the other, at the lengths of traverse stroke as shown in the following table:

In the above case, the high value of 0.048 cycle/second was selected in order to place the 1:1 ratio of scrambling frequency to traverse frequency just outside the range of package build. Then, the lower frequency of 0.03 84 cycle/second was selected in order to avoid the occurrence of an undistributed patterned region near to the bobbin surface, where pressures are greatest within the package.

Although an amplitude of 10% is exemplified above for the variation in spindle speed, it will be understood by those skilled in the art that, as the severity of patterning in the various regions of it will not be uniform through the package, a lesser amplitude, sa-y 3%-4%, may be adequate to disperse the patterning in certain of the regions; and thus, if the package is wound in such manner as to avoid the occurrence of patterning of the most severe nature, it may be possible, according to the invention, to employ such a lesser amplitude of spindle speed variation.

Likewise, it is within the scope of the invention to change the amplitude according to a programme, whereby the higher amplitudes are selected at those times during the winding when calculation has determined that regions of severe patterning will take place, and lower amplitudes are selected for the other calculated regions.

The principle, so far as amplitude is concerned, is to use the lowest amplitude consonant with the achieving of effective dispersion of the patterns; so that amplitudes greater than, say 15% will be unlikely to be needed or desirable.

We are aware of our co-pending application Ser. No. 661,771, filed on even date herewith which discloses the continuous monitoring and control of spindle speed scrambling frequency by, and directly in relation to, the traverse frequency.

We claim:

1. 'In the method of winding yarn by over-end winding on to a package with the aid of a rotating spindle and a traversing means, in which method the speed of rotation of the spindle is varied cyclically about the desired mean value during the winding of the package, the improvement comprising switching the frequency of such cyclical variation in spindle speed between at least two values, as the ratio of said frequency to the traversing frequency approaches values giving rise to any substantial degree of patterning, in a manner to avoid any value of said ratio ever being one consisting of small whole numbers either of which is less than 5 whereby regions of patterning in the package are avoided.

2. A method according to claim 1 in which the amplitude of said cyclical variation in spindle speed is between 3% and 15 of the instant mean spindle speed.

3. A method according to claim 2 in which said amplitude is itself changed according to a programme during the period of winding.

4. A method as in claim 1 including the step of electronically monitoring the traverse cycle to obtain a signal and wherein the frequency of the cyclical variation in spindle speed is switched in accordance with a function of said signal.

References Cited UNITED STATES PATENTS 2,658,689 11/1953 Waldrop 24218.l 3,137,987 6/1964 Potts 5755.5 3,235,191 2/1966 Engelman 242-l8.l 3,241,779 3/1966 Bray et al. 24218.1 3,325,985 6/1967 Bucher 242-26.3 XR

JORDAN FRANKLIN, Primary Examiner.

WERNER H. SCHROEDER, Assistant Examiner.

US. Cl. X.R. 57-93; 242-181