US3910514A - Method and apparatus for producing improved packages - Google Patents

Abstract

There has been provided an improved apparatus for building packages of yarn including a bobbin for taking up the yarn and a reciprocating guide member for reciprocating along the axis of rotation of the bobbin. The guide is driven by a controlled drive at a selected ribbon breaking rate for breaking patterns of ribbon formation. The improvement comprises means adapted to be coupled to the drive for modifying the ribbon breaking rate at a selected frequency modulation rate. The process employing the above apparatus utilizes the improved step of frequency modulating the ribbon breaking rate.

Description

Hooper Oct. 7, 1975 [5 METHOD AND APPARATUS FOR 3,241,779 3/1966 Bray et al, 242/181 PRODUCING IMPROVED PACKAGES 3,402,898 9/l968 Mattingly 242/l8.l X 3,434,673 3 /l969 Brouwer et al..... 242/l8.l Inventor: Clive Williams p 10, 3,514,682 5/1970 Corey 242/l8.l ux Canberra Crescent, Newport, 3,638,872 1/1972 Jennings 242/18.1 Monmouth, England, NPT 3QQ [22 Filed; May 22 1974 Primary ExaminerStanley N. Gilreath Attorney, Agent, or Firm-Cushman, Darby & [21] Appl. No.: 472,419 Cushman Related US. Application Data [63] Continuation of Ser. No, 261,670, June 12, 1972, 57 ABSTRACT abandoned, which is a continuation-in-part of Ser. No. 167,043, July 28, 1971, abandoned, which is a There has been provldedan Improved apparatus for continuation of Ser. No. 13,802, Feb. 24, 1970, building packages of yarn including a bobbin for takabandoned. ing up the yarn and a reciprocating guide member for reciprocating along the axis of rotation of the bobbin. [30] Foreign Application Priority Data The guide is driven by a controlled drive at a selected Mar. 4, 1969 United Kingdom 11490/69 ribbon breaking rate for breaking PatternS of ribbon n formation. The improvement comprises means [52] U.S. c1. 242/18.1 adapted to be coupled wthe drive for modifying the [51] Int. Cl. B6511 54/38 ribbon breaking rate at a Selected frequency modula- [58] Field of Search 242/l8.1, 43, 43.1; tion rate- 318/162-164 The process em loying the above apparatus utilizes P the improved step of frequency modulating the ribbon [56] References Cited breaking rate.

UNITED STATES PATENTS 21 Claims, 3 Drawing Flgures 2,763,824 9/l956 Bacheler 242/181 X I i M00041? roe US. Patent 00. 7,1975 Sheet 1 0f 2 3,910,514

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METHOD AND APPARATUS FOR PRODUCING IMPROVED PACKAGES REFERENCE TO RELATED APPLICATIONS This application is a continuation of application Ser. No. 261,670 filed June 12, 1972, now abandoned, which is a continuation-in-part of an application for IMPROVED PACKAGES, Ser. No. 167,043, filed July 28, 1971, now abandoned, which is a continuation of an application for IMPROVED PACKAGES, Ser. No. 13,802, filed Feb. 24, 1970, now abandoned.

BACKGROUND OF INVENTION The present invention relates to the building of packages of yarn, string and similar elongate objects and to packages so produced. It relates particularly, but not exclusively, to the building of packages of yarns of textile fibres.

SUMMARY OF INVENTION There has been provided an improved apparatus for building packages of yarn including a bobbin for taking up the yarn and a reciprocating guide member for 'reciprocating along the axis of rotation of the bobbin.

The guide is driven by a controlled drive at a selected BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view and block diagram of the appa ratus of the present invention.

FIG. 2 is a detail of certain aspects of FIG. 1.

FIG. 3 is a circuit diagram showing further details of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT The building of yarn packages is nearly always carried out by rotating a rod, cylinder, cone or similar elongate member, all such being designated by the term bobbin 10 in this specification. Said bobbin l0 driven by motor 11 for winding the yarn 12 onto said member. Guiding said yarn to and fro parallel with axis of said member is accomplished by a reciprocating guide member 13, called a traverse guide. Said guide 13 is usually located relatively near to the surface of the rotating bobbin 10 either at a fixed distance therefrom or moving gradually away therefrom, in such a way that as the package increases in diameter, its surface does not make contact with the traverse guide. The speed of rotation of the bobbin and the speed, frequency and amplitude of the traverse guide 13 movement may be varied nad interrelated in many different ways in order to produce packages having various desired characteristics and in order to reduce or eliminate the appearance of certain undesirable phenomena such ridging. The

guide 13 hereinis mounted to channel 14 and is driven in a reciprocating manner by drive 17 coupled through control member 18 which engages with the guide 13 to move it back and forth at selected amplitudes and frequencies. The amplitude and frequency variations of the guide 13 are governed by signals controlling drive 17 from summing amplifier 30, the operation of which shall be explained further in the specification.

The case of a simple square ended package 10 will be considered here for the sake of explanation. The shape and structure of the package may, however, be altered greatly from this simple shape in practice, for many reasons, but such alteration does not vitiate the present invention.

In this specification, the term wind ratio is defined as the package (or bobbin) rotational frequency divided by the traverse frequency.

The traverse frequency is the number of complete traverse cycles made by thetraverse guide 13 per unit time.

A traverse stroke is defined as the distance travelled by the point of lay of yarn 12 onto the bobbin between one point of direction reversal near an end face and the consecutive point of direction reversal near an end face.

A length of yarn 12 or other elongate object layed upon the package in one traverse stroke will be called a lay.

If said ratio is a ratio of integers, then at regular intervals during the package building, certain lengths of yarn will be layed directly (or nearly directly) above one or more other lays previously layed on the package, i.e., superimposed thereon. For instance, if the wind ratio is exactly 1, every lay of yarn will in theory be layed precisely. upon a preceding lay. Such a package is obviously undesirable because ribboning occurs. If the wind ratio is changed from unity to a ratio of small whole numbers (integrally related wind ratio) a honeycomb package may be obtained, with lays or parts of lays layed one upon the other along a package radius at fairly frequent intervals along said radius in a relatively simple pattern.

Such packages may be desirable in some cases, especially when bulk is not a prime objection or if, for exampmle, it is required to obtain penetration of some treatment fluid right through the package. Of course, by choosing a suitable constant wind ratio, good packages with other desirable characteristics can be obtained.

There are difficulties, however, associated with the system described, which difficulties increase rapidly with increasing speed of operation of the mechanism used. Some of the main difficulties are associated with the traverse apparatus itself.

Traversing usually entails moving member 13 rapidly in one direction and then reversing its direction very rapidly. For this reason it is often decided, when working package winding mechanisms at high speeds, to fix the traverse speed at an optimum value, above and below which undesirable stresses and strains arise in the apparatus.

In such a case, in order to maintain a constant wind ratio, the rotational frequency of the package must be kept constant and this means that the peripheral speed of the package will increaseas the package size increases. In many cases this is not desirable, because, for instance, of the danger of increasing tension of the yarn being wound onto the package, so producing a a package with yarn properties varying throughout the package. Hence, in general, it is desirable that the package peripheral speed remain constant. I

The present description will be made, for simplicity of comprehension of the present invention only and in no way limitatively, with reference to a system wherein the bobbin peripheral speed is maintained constant as well as the traverse speed. This entails a gradual. slowing down of the bobbin l rotational frequency and hence, to the abandonment of a system having a constant wind ratio;

Of course, in practice many much more complicated programmes are used, but the. simple case here described is for simplicity of illustration only.

lf the bobbin rotational frequency is, for instance, gradually monotonically reduced in accordance with increasing radius, the wind ratio will decrease monotonically and integrally related wind ratios may be passed through several times during package building. Thus, superimposing of yarn lays or parts of lays will occur to some extent as such ratios are approached and left behind. Groups of superimposed yarn lays or parts of lays, particularly when lay deflections defined hereinafter occur, will therefore be produced. Troublesome cases in practice are produced when lays cross over one another while substantially parallel. The most troublesome cases are concerned with lay reversals and such reversal groups will be observable at the ends of the package, assuming traverse speed and amplitude are maintained constant. Lay crossings and lay crossing groupings may occur at any point along lays. Particularly' troublesome are superimposed lay deflection groups. If the programme is complicated, for instance, by slight changes in traverse speed or amplitude, whethersuch changes be exactly repeated or not, some such aforesaid reversal groups may be set back from the package end surfaces and, though not observable, will still be present.

The aforesaid lay crossings, especially if such crossing is repeated at several points along the same packages radius or near it, may produce more or lessobjectionable package surface ridging and other 0bjectionable features associated therewith such as periodical variation in take-off tensions when, the yarn is later removed from the package. t

In order to reduce thee objectionable features it has been found beneficial to use a short term cyclical variation of traverse speed to modify a longer term variation of traverse speed or a substantially constant traverse speed. This modifying variation of traverse speed brings it about that the various undesirable ratios which are gone through during package building, exist for shorter periods than without it and are distributed more evenly throughout the package.

In particular, those ranges of wind ratios giving honeycomb patterns or certain ribbon patterns on the surface of the package and corresponding ridges on the end faces of the packages are distributed more evenly through the packagewhence the method is generally known as ribbon breaking.

The amplitude and time period of the aforesaid modifying variation of traverse speed define the ribbon breaking rate and are normally chosen empirically. Such modifying variation will be called hereinafter simply ribbon-breaking. Typical values for ribbon break ingare i variation of traverse speed according to a triangular, sinusoidal or square waveform with time, and a cycle time of about 10 0 times the traverse cycle time. It is known to choose the rate of variation of traverse speed in such a way that no more than seven lay reversals are laidclose to each other at a time when the wind ratio is close to a ratio of small integers, such ratio giving a honeycomb pattern especially when one integer is unity.

In those cases where package stability approachesits limit, e.g., when large packages arewound at high of constant wind ratio entails the disadvantage of in- I creasing package peripheral speed or that of decreasing traverse speed both, of which entail serious disadvantages at high operational speeds. Furthermore, with a non-constant wind ratio the ridges on the end faces are not reduced to a satisfactory level despite such measures the above choice of the ribbon breaking cycle time and amplitude.

It has been found that suitable modification imposed on the aforesaid ribbon breaking rate reduces the formation of superimposed yarn lay groups to a surprising degree.

Of course, some modification may occur to a very I small extent due .to variations brought about by adventitious variations in speed of machinery itself. However, the present invention, wherein'such further modification of the ribbon breaking rate is strictly controlled in form, velocity and amplitude, gives much more uniform and much more predictable results than any said adventitious variations.

The modulating apparatus of FIG. 1 generates output signals whichare coupled through summing amplifier 30 to drive 17 having a static inverter therein (not shown) which produces an output oscillatorysignal :at a rate governed by modulator 31, for con'troling the tra-. verse guide 13, frequency and amplitude. The electronic system 31 herein includes electronic analoge computing circuits used to control the traverse fre quency in the manner required for yarn lay production in Examples l to 9 described further in the description. The function of the elements in this diagram are first described, before considering their operation in more detail.

The traverse drive 17 is governed by outputs of modulation'network 31. In controlling the static inverter in the drive, the frequency of the traverse 13 corresponds to the frequency of a transistor oscillator therein (not shown). Thefrequency of this oscillator is determined by the voltage supplied to it from a summing amplifier I 30. This amplifier 30 linearly combines three inputs from preset amplitude controls 32,33 and 34 having outputs governed by settings of laycontrol dials 32",

33, 34 which provide respectively, a steady voltage percentage of the mean frequency; this in Example l,

the mean traverse frequency has a superimposed deviation of 4% and in Examples 2 9 the deviation from the mean is 10%. The frequency of this triangular waveform previously described as ribbon breaking is itself varied in Examples 1, 3, 5, 8 and 9, and which therefore used a modified ribbon breaking waveform. To achieve this modification a waveform generator 35 is arranged for frequency modulation (as is the transistor oscillator within the static inverter), being fed from a summing amplifier 36 and also from an inverting amplifier 37 which provides a second input of opposite sign required by the modulation circuit 35.

The summing amplifier 36 linearly combines three inputs from generators 38, 39, and 40, having outputs controlled by settings of lay preset controls 38, 39' and 40', which provide respectively a steady voltge corresponding to the mean ribbon breaking frequency (in Examples 1 to 9 this is cycles per minute), a triangular waveform (of constant amplitude and preset frequency), and a noise voltage whose amplitude varies randomly with time and having an amplitude/frequency spectrum falling'at 6db/octave to either side of 0.8Hz. To replace this last triangular (modifying) waveform with noise from the noise generator it is sufficient to set a present control 39 to zero (thus removing the corresponding input to the summing amplifier) and to set control 40' to give the desired amplitude of noise. A noise generator 43 is provided which has been described by Yeowart (Electronic Engineering, April, l968, p.212), the output being coupled through a filter 44 giving the required 6db/octave cut off to eitherside of 0.8HZ.

The third input tosumming amplifier 30 is rectangular waveform derived from thefrequency modulated waveform generator and inphase with the main tri-' angular wave output. lnverting amplifier 41 changes the sign of this rectangular waveform and preset control 34 adjusts the amount fed to the traverse drive 17 so as to compensate for the delay of the traverse mechanism to the change in slope of the triangular (ribbon breaking) rate at its reversals, and thereby obtain a more rapid reversal of the ribbon breaking waveform.

A control setting indicated by reference numeral 42 is provided for the triangular waveform generator or oscillator 45 and the noise generator 43 can have an adjustable setting to regulate the noise output thereof.

Turning now to a consideratin of FIG. 3, there is shown detailed circuitry of the arrangement of FIG. 2. The circuitry utilizes nine operational amplifier circuits labeled A1 through A9 and which are utilized for various functions as hereinafter described. Each ofthese operational amplifiers can be of the type manufactured by S.G.S. Fairchild Ltd., and designated as No. A702.

The output to the traverse drive unit 17 from summing amplifier 30 operates satisfactoraly at 5 Volts maximum means coresponding to maximum mean traverse speed. Amplifier A9 is adapted in an Add Mode together with Resistors R28, R29, R30and R31 making up summing amplifier 30. The amplifier A9 output Here V V and V are the voltages at sliders of the respective control dials 34, 33 and 32" '(VRZS, VR26 and VR27).

By way of Example a 12 volt voltage reference source 47 is provided connected to VR27, R31 is chosen to equal l0 ohms, R30 2.4 X 10 ohms, R27 5.0 X 10 ohms, and R28 8.0 X 10 ohms and using linear wire wound potentiometers for the preset controls, their dials (0 to 100 divisions) read 32',33 and 34 respec tively) mean traverse speed as a percentage of max value (100 divs max speed), peak to peak traverse speed change (100 divisions 40% of max traverse speed), and peak step in demanded traverse speed at reversal of ribbon breaking (100 divisions 10% of max traverse speed). Dials 32', 33, 34, govern the speed settings given in the examples or could be readily found, whilst the setting of preset 34 may be determined empirically by observing the waveform of traverse speed against time using a recording frequency meter from whose record the ribbon breaking reversal time could be found. In this way a triangular wave may be superimposed at a certain percentage on a steady voltage. To determine the frequency of the triangular waveform the operation of the main ribbon breaking oscillator 35 is considered.

This frequency modulated oscillator, includes amplifiers A6 and A7 functioning as a comparator and as an integrator respectively together with the diode bridge D5, D6, D7 and D8. A bridge driving amplifier A and a summing amplifier A is in principle the same as A9 already described. The output of the comparator A6 is limited by the Zener diodes 2;, and Z to 6.8 volts (R ,,=200 ohms as current limit) and, being set to one limit, switches very rapidly to the other when the output of the integrator A7 has risen to make the current through R exceed the magnitude through R the cycle then continuing. The charge and discharge time of the integrator A7 forgiven values of C resistance chain (R16 (or R17) VR21+ R22) and for symmetrical voltage swing (i 5 volts) may bedetermined by the input current through the diode bridge. This in turn may be set by the output voltage from A or A the bridge selecting the sign of voltage to agree with that of the comparator A6 output. The frequency of the frequency modulated oscillator is controlled by outputs of the amplifiers A, and A driving the bridge circuit. In certain of the examples described further in the specification, the frequency resistances R13, R14, R15, R16 and R17 were chosen to be 10 ohms. A 12 volt voltage reference source 46 is provided connected to the control setting 38. Setting controls 39' and 40 to Zero and 38'to divisions (80/100 of full scale 9.6 Volts output), the value of R10 was adjusted on test (approx. value 2.4 X 10 ohms) to give A output =4 Volts, and the value of R (=10 ohms) was adjusted to give A output +4 Volts. Using C, 10 fd and R22 10 ohms the value of potentiometer VR21 was set to approx 2.0 X 10 ohms so as to give an oscillator cycle time of 2 seconds. This corresponded to the oscillator frequency of 30 cycles per minute specified in the Examples l to 9 and could be adjusted by 38 divisions 37.5 cycles/Minute) and checked with a digital frequency meter which was conveniently applied to the zener diode pair Z and Z When thefrequency and amplitude of the triangular waveform from the ribbon breaking oscillator are set inthis way, the oscillator output remains constant at i 5.0 Volts during changes in frequency,

Such changes in frequency are provided, in Example 1, by the triangular wave oscillator (A and A through 7 39, while 40 was set to zero. Similarly in Examples 3, 5,8 and 9,39 was set to zero and 40 was set to give the stated changes in ribbon breaking frequency. In

this way a noise waveformlwas substituted for the triangular waveform.

The oscillator A and A maybe setto give i 5 Volts at a frequency of (30/32) cycles per minute for Example 1. Thus, C was chosen to be '3() .tfd and R set at 5.6 X 10 ohms, Z, and Z being 6.8 Volt Zener diodes (as were Z and Z R adjusted in the region of 4.1 X 10 ohms to give 1 5 volts at A output and VR4 at an output of amplifier A was set (R, was 200 ohms as a current limiter). R1] was chosen to be 2.5 X I ohms, giving 100 divisions (full setting on VR8)-equal to i 40% frequency deviation of oscillator A., and A for the given setting of 38.

The noise generator 43 supplying A was set to. give 1 volt R.M.S. into C corresponding to a range ofinput.

voltages within i-4V peak to peak. C was set to 20 fd and R to It) ohms; R was set to 6.2. X 10 ohms and C to 32 fd, giving the 0.8Hz center frequency as required together with a range of noise input i 2.5 Volts at 40' input. R12 was then chosen tobe 10 ohms giving I00 divisions on VR9 =rt 50% peak frequency deviation. The value of 15%, 25%and 40% used in Exam ples 6, 5 and 3 and 9 were then obtained'by changing the setting of 40'as required.

The inverting amplifier (41 )A8 was supplied with i 6.8 Volts from zener diodes Zgand Z Choosing R24 10 ohms, R23 (about 1.7 X 10 ohms) was set on test to give 4.0 Volts at amplifier A8 output.

The amount by which the conventional ribbon breaking rate is modified is important.The percentage modification is defined as the percentage change about the mean frequency or mean amplitude or both of the ribbon breaking rate. Preferably such percentage modification lies above 2% and more preferably between 2 and 50%. A most preferred range is 5 30%.

The present invention, therefore, comprises in one aspect a process for building improved packages of yarn, string or similar elongate object in which process the wind ratio varies and wherein a modification is imposed on the ribbon breaking rate as defined hereinbefore which modification introduces low frequency components removing at least one coincidence of lay deflection groups defined hereinafter.

In order to define the characteristics of the aforesaid improved packages recourse is bad to the following definitions.

Angle of Lay This is the angle between the direction of lay of the yarn or other elongage object, at any point on the package, and a plane normal to the axis of rotation of the package and passing through said point;

A lay reveral is a special case of a lay deflection, typically occurring at the end face of a package.

Deflection Angle 6 This is defined as the angle at the axis of rotation of the package between the two planesjust containing the lay deflection and intersecting at said axis of rotation.

Deflection Group A group of consecutive lay deflections such that all said deflections lie within an 7 angle 26, where 0 is defined above and dis the mean 0 of the deflection group.

Coincidence of Deflection Groups This is defined as occurring when the mean positions of two deflection groups subtcnd an angle (1) at the axisof rotation of the 7 In another aspect the present invention comrises a.

package of yarn, string or similar elongate object in which deflection groups are distributed randomly around the circumference of the package,

In yet another aspect the present invention comprises a package of yarn, string or other elongate object wherein there is substantially no coincidence of deflection groups as defined hereinbefore.

The, aforesaid modification to the conventional rib bon breaking ratecan be regarded, generally, as the ad dition of other, and particularly lower, frequencies so as to make. a more complex wave form. Such modification may. be achieved, for example. by the addition of modulated triangular, or sinusoidal waveforms or of random noise previously mentioned. Furthermore, it may be achieved by modulation either in terms of amplitude or frequency of traverse, both of these being special cases of the addition of other frequencies.

' It has been found that amplitude modulation while of use in some cases, is considerably less effective than frequency modulation, because the basic repetition time remains unaltered and so wind ratio transits occurring close to the the mean value of the ribbon breaking rate will not be greatly altered in position by amplitude modulation.

One possible method of achieving modification of the ribbon breaking rate is to frequency modulate theribbon breaking rate according to a second, longer period, triangular or sinusoidal waveform. Whilst this method gives an improved package, it nevertheless has the disadvantage of retaining a longer-period cyclical relationship between the package rotation time, the ribbon breaking .cycle time and the modulation cycle time. This is particularly disadvantageous when package building lasts for a long time, for instance when building packages of 'a very fine yarn. I

A further increase in the duration of said longerperiod relationship can be obtained using frequency modulationwhich, in Fourier analysis terms, contains lower frequency components. Such a modification imposes wave forms which when frequency analyzed in a Fourier .series contains lower frequency components than those in a similar series for the unmodified wave-- form. Such a waveform may be obtained. for example,

' by adding together two or more triangular or sinusoidal waveforms having successively lower frequencies, each being typically between /1 and H10 of the next higher frequency in the set of modulation frequencies, the highest being similarly related to the mean ribbon breaking frequency. The effectiveness of such a waveform is increased if the several waveform generators employed have cycle times which do not repeat exactly or have noise components. It is also possible to replace part or all of such modification frequency generators by a random noise generator. The frequency range within which energy from the noise generator is supplied to the ribbon breaker modulation system extends downwards from a value corresponding typically to about A; to 1/10 of the mean ribbon'breaking cycle or from the lowest frequency in the above described set of one or more modulation frequency generators, to a lower limit of frequency the cycle time of which is at least greater than the time necessary to allow the rate of growth of package diameter to cause a change in the package rotation period sufficient to disturb the integral relationship between ribbon breaking cycle and package revolution time.

The actual means of achieving theobjects of the present invention depend on the design of the package and the winding equipment on which it is intended to be used. It has been found particularly convenient, especially in view of the convenience of use of an electronic random noise generator, to use electrical signals for the modifying waveforms as shown in the drawing. Mechanical or hydraulic generators could, of course, be used if more adaptable to the winding equipment in use.

The following examples are for illustration only and in no way limitative of the invention.

EXAMPLE 1 The packages produced were wound at 9,500 feet per minute from multifilament nylon 6.6. yarn of 205 denier and containing 34 filaments with a inch peakpeak traverse The approximate parameters of the variation in traverse cam speed are as follows:

2. Peak to peak variation 3. Mean frequency of variation 4. Percentage modulation 5. Modulationfrequency 6. Calculated maximum rate of change of cam speed.

7. 'lraverse cam speed reversal time (time from turning point to cam speed change completion.)

160 milliseconds.

Packages were made both with and without the mod-- ulation described in items 4 and 5 above. The packages made with modulation were considerably less ridged on the end faces than those made without. Examination of the process to show the distribution of deflection groups showed that fewer coincidences of deflection groups took place with the above-defined modulation.

EXAMPLES 2 9 The process of example 1 was repeated, but instead of the triangular wave, noise from waveform generator 43 was superimposed at various levels. The generator 43 contained a filter (not shown) which produced a spectrum whose envelope fell off at 6 decibels per oetave on either side of 0.8 Hertz (cycles per second).

Furthermore, the packages were wound at 2700 feet per minute, with the following parameters:

Traverse stroke 5V2" length Container diameter 4V2 Package weight 4.72 lbs. Outside package diameter 7% Winding tension The results are shown in Table l.

22 gms: constant In the case where noise was superimposed on the ribbon breaking waveform the following variation parameters pertained:

Mean frequency of variation of ribbon breaking waveform 30 cycles/min.

Mean amplitude variation of ribbon breaking waveform 10% end face but slightly more than in example 8.

From the results given in Table 1 it can be seen that 25% modification by the noise generator gives a considerable improvement in ridging of the package endface, which is a measure of deflection group coincidence.

As expected from prior art, and as shown by comparison of examples 6, 4 and 2, an improved appearance of the end faces was obtained by an increase in traverse speed, which is undesirable. A relative increase in traverse speed can be obtained by decreasing the yarn speed but this is also undesirable from the productivity viewpoint.

The imposition of 25% modification with traverse speeds of both 475 and 415 c.p.m. produced a considerably improved end face.

It is known to decrease end face rigidness by sharpening the ribbon breaking waveform (i.e. reducing traverse cam reversal time) and this was done in examples 7 9. Comparison of examples 6 and 7 shows the expected improvement. Example 8 shows that still further improvement is obtained by the imposition of 15% modification. When the percentage is increased to 40% there is still a better appearance than with no imposed modification but the results are not quite so good as with 15%.

Furthermore, whilst the present invention has been particularly described with reference to the building of packages of yarn it can clearly be applied to the building of packages of any other elongate objects such as wire, string and the like.

While there has been described what at present is the preferred embodiment of the present invention, it will be obvious to those skilled in the art that various changes and modifications may be made herein without departing from the invention and it is extended in the appended claims to cover all such changes and modifications as come within the scope of the present invention.

What is claimed is:

1. An improved control for use with apparatus for winding yarn on a bobbin including a drive means for driving the bobbin, a traversing mechanism for repetitively traversing the yarn axially along the surface of the bobbin during wind up, and control means for the.

traversal mechanism for generating a rate control sig nal for driving the mechanism at a selected rate, said control means including means setting a mean driving rate signal as part of said rate control signal, ribbon breaking rate means for continuously generating a relatively long term cyclically varying signal as part of said rate control signal for varying the rate control signal between predetermined fixed limits respectively above and below the mean driving rate signal, and wherein said control means further includes modifying means for continuously generating a relatively short term varying signal as part of said rate control signal for continuously modifying the rate at which the rate control signal is varied between the predetermined fixed limits.

2. The apparatus as described in claim 1 wherein said modifying means comprises an oscillator for producing a modulating signal, thereby producing continuous modulation of the relatively long ,term cyclically varying signal between the fixed predetermined limits.

3. The apparatus as described in claim 2 wherein said modulating signal comprises a triangular wave form.

4, The apparatus as described in claim 2 wherein said modulation signal compries a sinusoidal wave form.

5. The apparatus as described in claim 2 wherein said modulation signal comprises random noise signals.

6. The apparatus described in claim 2 wherein said modulation comprises modulation of said long term cyclically varying signal at least greaterthan 2 percent.

7. The apparatus as described in. claim 2 wherein said modulation comprises modulation of said long term cyclically varying signal between 2 and 50 percent.

8. The apparatus asdescribed in claim 2 wherein said modulation comprises modulation of said long term cyclicaily varying signal between 5 and 30 percent.

9. The apparatus as described in claim 2 including means for varying the frequency and amplitude of said modulating signal.

10. The apparatus described in claim 2 wherein said oscillator includes first, second and third means respectively adapted for generating a triangular waveform, a sinusoidal waveform and random noise outputs,

amplitude control means for each first, second and third means adapted for controlling the amplitude for its respective output and frequency control means for each first, second and third means adapted ,to control the frequency thereof.

11. The apparatus as described in claim including summing means adapted to be selectively coupled between the outputs of said first, second and third means and said traversal mechanism, said selected rate varied in accordance with said summed outputs.

12. A process for building packages, of yarn, string and similar elongate objects in which a bobbin is supplied with yarn and is driven at a selected speed and a traversing mechanism repetitively traverses the yarn axially along the surface of the bobbin during the wind up at a selected traverse rate comprising the steps of i cyclically'and continuously varying the traverse rate between fixed predetermined limits on each side of a mean traverse rate to define a ribbon breaking traverse rate, and continuously modifying the ribbon breaking traverse rate by modulating it with a short term varying 1 signal to vary the ribbon breaking traverse rate between the fixed predetrmined limits.

13. The processas described in claim 12 wherein said modulation of the ribbon breaking traverse rate comprises frequency modulation thereof.

14. The process described in claim 12 wherein the step of modulating the ribbon breaking traverse rate is carried out with a short term varying signal having a frequency and amplitude such that the modulated rib bon breaking traverse rate contains lower Fourier series frequency components than an unmodulated ribbon breaking traverse rate.

15. The process described in claim 12 wherein said step of modulation is performed with a triangular wave-, form modulating signal.

16. The process as described in claim 12 wherein said step of modulation is performed with a sinusoidal waveform modulating signal.

17. The process described in claim 12 wherein said step of modulation is performed with a random noise modulating signal.

18. The process as described in claim 12 wherein said modulation of said ribbon breaking traverse rate is carried out to an extent sufficient to produce between 2 andSO percent modulation thereof.

19. The process as described in claim 12 wherein said modulation of said ribbon breaking traverse rate is carried out to an extent sufficient to produce between 5 and 30 percent modulation thereof.

20. The process as described in claim 12 wherein said modulation is carried out with a modulating signal which is the sum of a triangular waveform signal, a sinusoidal waveform signal and a random noise waveform signal.

21. The process as described in claim 20 including the step of selectively varying the frequency and amplitude of each of said triangular, sinusoidal and random noise signals.

Claims (21)

1. An improved control for use with apparatus for winding yarn on a bobbin including a drive means for driving the bobbin, a traversing mechanism for repetitively traversing the yarn axially along the surface of the bobbin during wind up, and control means for the traversal mechanism for generating a rate control signal for driving the mechanism at a selected rate, said control means including means setting a mean driving rate signal as part of said rate control signal, ribbon breaking rate means for continuously generating a relatively long term cyclically varying signal as part of said rate control signal for varying the rate control signal between predetermined fixed limits respectively above and below the mean driving rate signal, and wherein said control means further includes modifying means for continuously generating a relatively short term varying signal as part of said rate control signal for continuously modifying the rate at which the rate control signal is varied between the predetermined fixed limits.

2. The apparatus as described in claim 1 wherein said modifying means comprises an oscillator for producing a modulating signal, thereby producing continuous modulation of the relatively long term cyclically varying signal between the fixed predetermined limits.

3. The apparatus as described in claim 2 wherein said modulating signal comprises a triangular wave form.

4. The apparatus as described in claim 2 wherein said modulation signal compries a sinusoidal wave form.

5. The apparatus as described in claim 2 wherein said modulation signal comprises random noise signals.

6. The apparatus as described in claim 2 wherein said modulation comprises modulation of said long term cyclically varying signal at least greater than 2 percent.

7. The apparatus as described in claim 2 wherein said modulation comprises modulation of said long term cyclically varying signal between 2 and 50 percent.

8. The apparatus as described in claim 2 wherein said modulation comprises modulation of said long term cyclically varying signal between 5 and 30 percent.

9. The apparatus as described in claim 2 including means for varying the frequency and amplitude of said modulating signal.

10. The apparatus as described in claim 2 wherein said oscillator includes first, second and third means respectively adapted for generating a triangular waveform, a sinusoidal waveform and random noise outputs, amplitude control means for each first, second and third means adapted for controlling the amplitude for its respective output and frequency control means for each first, second and third means adapted to control the frequency thereof.

11. The apparatus as described in claim 10 including summing means adapted to be selectively coupled between the outputs of said first, second and third means and said traversal mechanism, said selected rate varied in accordance with said summed outputs.

12. A process for building packages of yarn, string and similar elongate objects in which a bobbin is supplied with yarn and is driven at a selected speed and a traversing mechanism repetitively traverses the yarn axially along the surface of the bobbin during the wind up at a selected traverse rate comprising the steps of cyclically and continuously varying the traverse rate between fixed predetermined limits on each side of a mean traverse rate to define a ribbon breaking traverse rate, and continuously modifying the ribbon breaking traverse rate by modulating it with a short term varying signal to vary thE ribbon breaking traverse rate between the fixed predetrmined limits.

13. The process as described in claim 12 wherein said modulation of the ribbon breaking traverse rate comprises frequency modulation thereof.

14. The process as described in claim 12 wherein the step of modulating the ribbon breaking traverse rate is carried out with a short term varying signal having a frequency and amplitude such that the modulated ribbon breaking traverse rate contains lower Fourier series frequency components than an unmodulated ribbon breaking traverse rate.

15. The process as described in claim 12 wherein said step of modulation is performed with a triangular waveform modulating signal.

16. The process as described in claim 12 wherein said step of modulation is performed with a sinusoidal waveform modulating signal.

17. The process as described in claim 12 wherein said step of modulation is performed with a random noise modulating signal.

18. The process as described in claim 12 wherein said modulation of said ribbon breaking traverse rate is carried out to an extent sufficient to produce between 2 and 50 percent modulation thereof.

19. The process as described in claim 12 wherein said modulation of said ribbon breaking traverse rate is carried out to an extent sufficient to produce between 5 and 30 percent modulation thereof.

20. The process as described in claim 12 wherein said modulation is carried out with a modulating signal which is the sum of a triangular waveform signal, a sinusoidal waveform signal and a random noise waveform signal.

21. The process as described in claim 20 including the step of selectively varying the frequency and amplitude of each of said triangular, sinusoidal and random noise signals.

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