US3488938A - Method and apparatus for winding yarn - Google Patents

Description

6 Sheets-Sheet 1 B. K. JOHNSON ETAL METHOD AND APPARATUS FOR WINDING YARN Jan. 13, 1970 Filed April 5, 1965 Jan. 13, 1970 B. K. JOHNSON ETAL 3,488,938

METHOD AND APPARATUS FOR WINDING YARN Filed April 5, 1965 s Sheets-Sheet 2 11/1/11 I I II I! I II B. K. JOHNSON ETAL 3,488,938

METHOD AND APPARATUS FOR WINDING YARN 6 Sheets-Sheet 5 5 SID/N015 5/ 550 (Relax/0 1 Jan. 13, 1970 Filed April 5, 1965 Jan. 13, 1970 B. K. JOHNSON ETAL 3,488,938

METHOD AND APPARATUS FUR WINDING YARN Filed A r'ns, 1965 v e Sheets-Sheet 5 Jan. 13, 1970 B.- K. JOHNSON HAL METHOD AND APPARATUS FOR WINI DING YARN 6 Sheets-Sheet 6 Filed April 5, 1965 United States Patent.

3,488,938 METHOD AND APPARATUS FOR WINDING YAI N Bryan K. Johnson, Abergavenny, and Frederick A. Smith, Malpas, Newport, England, assignors to British Nylon Spinners Limited, Pontypool, Monmonthshire, England Filed Apr. 5, 1965, Ser. No. 442,858 Claims priority, application Great Britain, Apr. 4, 1964, 13,986/ 64 Int. Cl. D01h 13/00; D02g 3/02 US. Cl. 57-98 11 Claims ABSTRACT OF THE DISCLOSURE An apparatus and process for the preparation of cylindrically-wound yarn packages characterized by a relatively high helix angle and reduced ridging, the process including programming means arranged to control the winding conditions by varying winding speeds in a manner such as to reduce ridging.

This invention relates to a method and apparatus for winding yarn in the form of cylindrically-wound packages, in which the yarn is laid with a relatively high helix angle, and associated therewith is drive means including means by which the speed of the spindles on which the packages are being formed is variable during the winding of the packages.

The term cylindrically-Wound package used above refers to packages in which at least a part of each layer of yarn is wound so as to form part of a cylindrical portion of the package (although not necessarily a right cylinder). Thus, the packages may be wholly of cylindrical form i.e. cheeses, or be of other forms of build, such as conicalended packages of, for example, pirn or long-to-short build.

Further, for convenience, in this specification, the chuck o-r spindle upon which the package container is clamped during the winding operation will be referred to as a spindle, irrespective of whether a wholly cylindrical package or a conically-ended package is formed thereon.

The term helix angle is used in this specification to refer to the maximum angle of inclination of the curve representing the developed view of the lay of the yarn on the package, to the mean axis of this curve, and a relatively high value for this angle is an angle in excess of 1, although it may vary throughout the winding of a package.

The kinds of winding apparatus to which the present invention applies are as follows:

(a) Apparatus for the formation of wholly cylindrical packages, hereinafter for convenience referred to as cheeses, having a rotating spindle and reciprocating traverse yarn guide means, the spindle speed being proportional to the ratio of the yarn delivery speed to the package diameter while the traverse guide speed is variable, independently of the spindle speed, at will (as compared to winding arrangements in which the spindle and yarn traverse guide means are driven by common driven means, and at speeds which are not independently variable, except by an interruption of the driving of one or both parts).

There are predictable points during the winding operation of either form of such winding apparatus, when the number of spindle revolutions per traverse cycle of the yarn guide is either a small integer or a ratio of small integers at these points, hereinafter referred to as wind ratios, these wind ratios corresponding to periods during the winding opeation when the yarn in one layer of the package is laid directly on the yarn of layers laid immediately previously, at these wind ratios this synchronisation of the winding causing ridges of yarn to be produced within the package structure.

It will be understood that, in such a winding arrangement, the winding conditions at any particular package diameter, comprise the spindle speed, traverse yarn guide speed and the yarn delivery speed.

(b) Apparatus for winding, say, a conica1ly-ended package, having a driven spindle and over-end yarn guide means, for example, a ring and traveller guide device, the yarn being laid on the package in the form of closely wound helical turns with a sinusoidal wave-form superimposed thereon, due to, say, the axis of the ring of a ring and traveller yarn guide device being inclined to the spindle axis.

For convenience hereinafter such packages produced by over-end winding apparatus will be referred to as conically-ended package.

The winding apparatus will be assumed to include a ring and traveller yarn guide device, although other forms of over-end winding such as cap-spinning would also be applicable as they usually have tapered end portions.

In such a case, on either side of certain predictable points in the winding operation, parts of the sinusoidal curves of yarn merge together to produce a fine patterned effect in the surface relief of the package.

The winding conditions associated with such a winding arrangement, and at any particular package diameter, comprise the spindle speed, the winding-on speed of the yarn, the traveller speed, the type of build of the package and the angle of inclination of the axis of the ring to the spindle axis.

For any over-end winding arrangement for producing comically-ended packages it is possible to derive the following equation:

in which S is the spindle rotational speed, T is the ro tational speed of the traveller (in the requisite units), and W is the fraction of the spindle rotational speed corresponding to the winding-on of the yarn.

The winding speed W of the yarn is equivalent to the package rotational speed in the case of the cheese winding operation referred to above, and would be equal in magnitude to the spindle rotational speed if the traveller was stationary (i.e. T :D).

The points associated with the patterning, on the package in the winding of comically-ended packages correspond to the wind ratios of the cheese winding arrangement, and are when the ratio of T:W is either a small integer or a ratio of small integers.

These ratios also may be called wind ratios, and are equivalent to the wind ratios referred to above with respect to the formation of cheeses, although the manner of formation of ridges on cheeses dilfers from that of the patterning on the comically-ended packages, and both the problem of the reduction of ridging and the reduction of patterning may be solved in equivalent ways.

The present invention is especially concerned with overend winding apparatus in which it is possible to control the value of S at will, and either consequently, or otherwise, to control some such aspect of the winding operation throughout the production of a comically-ended package.

The value of the term T may be varied at will, or be maintained at a constant value, by appropriate changes in the value of S (the value of W Varying so that the relation S=T+W is obeyed). Thus, the winding conditions may be chosen so that certain desired objects are achieved with respect to the production of the yarn packages, for example, so that the balloon tension of the yarn is maintained at a substantially constant value throughout the winding operation to produce a yarn package.

In this case, the winding apparatus includes programming means so that, the spindle speed S is varied through out the winding operation, in a manner ensuring that T is proportional to the package diameter, and thus the Jalloon tension of the yarn is maintained at a substantially constant value, barre being reduced in fabrics produced :rom synthetic polymer yarns so wound. In this respect, he traveller of a ring and traveller device can be assumed to be a wind-on guide whose speed is proportional to :he yarn tension, and not solely as a means of inserting :wist into the yarn, the function of a ring and traveller yarn guide, including the insertion of twist into the yarn and ensuring that a stable balloon is maintained by ten- ;ioning the running yarn to the requisite amount.

The tension in the running yarn is usually adjusted so to approximate to its minimum acceptable value for 1 stable balloon, so that a container construction which is is flimsy as possible may be used.

The uniform tensioning of the yarn throughout the fornation of the package, implies that defects in fabrics nade of synthetic polymer yarns so wound, such as barre )1 warp-stripes are reduced. Yarns taken from such packlges will also have a better warping performance.

Alternatively, the winding programme, for an over-end vound comically-ended package, may be arranged to en- ;ure that the yarn guide moves at a constant speed, so as o minimise strain within the yarn guide device, but with l gradually reducing yarn tension throughout the winding )peration.

There is also the effect, associated with synthetic linear olymer yarns, which causes the retraction in length of .he yarn over a prolonged period after it has been renoved from a package and is not maintained in tension. For convenience hereinafter, this effect will be referred :o as air retraction, and is measured normally by noting, )ver an extensive period of time, the change in length of 1 yarn, which yarn when freshly removed from a package s subjected to only sufiicient load to keep the yarn straight n air and free to retract. It is found that the greatest nagnitude of this effect is associated with yarn taken from near to the core of the package, is less with yarn .aken from the middle of the packages (after approxinately a quarter of the package has been wound), and hen rises again with yarn from the outer layers of the package.

This effect can be reduced by decreasing the spindle xpeed at the periods in the winding programme corresponding to high air retraction, and vice versa. The action of :he winding apparatus in this case, is closely associated to :he manner of operation for maintaining at a constant value the balloon tension of the yarn, referred to above (in this case, of course, the balloon tension being deliberitely varied in a predetermined manner during the windlng operation to achieve the desired object).

Similarly, the spindle speed may be programed during :he winding operation, causing the yarn balloon tension to vary, but controlling the value of the yarn denier, or its initial modulus, or the twist insertion rate.

It will be appreciated, that in any event, the maximum productivity of any given winding apparatus will only 3e realised if the maximum yarn delivery speed is em- Jloyed, and this factor may have to be taken into account when programming the winding apparatus.

In this connection, a further reason for reducing the ipindle speed during the winding operation, is to ensure .hat, as the inertia of the container and package increase, :he torque on the spindle does not exceed the maximum lesign specification for this part of the winding machine, if the torque on the spindle is kept as close to the design lPCCifiCHIlOI'l value as possible, the maximum attainable :fficiency of the winding apparatus may be obtained.

In addition to programming the winding apparatus in )rder to obtain any one (or combination), of the above lesired objects, it is also possible to ensure that the packige has an adequate stability, by providing that the turns )f the yarn, particularly if it is a synthetic polymeric mm with a relatively smooth surface, cross over each other at a relatively high helix angle, so as to interlock one with another.

This desired object may be obtained by, say, tilting the axis of the ring of a ring and traveller device, in the case of the over-end winding of a conically-ended package, (or by having a high traverse frequency associated with the winding of cheeses).

Further, it is desired that the axis of the ring of a ring and traveller device inclined to the spindle axis, so that, in addition to the package so produced having increased stability, the take-off tension associated with the final layers of yarn, to be unwound from such a package, is less than that associated with a package wound without ring tilt.

In practice, all rings will tilt, perhaps unintentionally due to the mounting of the ring, but the extent of the patterning within the package usually, will be greater when the ring tilt angle is intentionally arranged to be finite, this value normally being greater than 1, and possibly greater than 3. Unfortunately, it is just the above-mentioned conditions, for package stability which cause patterning to be formed on comically-ended packages (and ridges to be formed on cheeses).

In a cheese winding arrangement, in which the reciprocating motion of the traverse guide has a relatively high frequency associated therewith, then ridging will occur, as the criterion for enhanced ridging is present, i.e. that there should be a relatively high helix angle associated with the manner in which the yarn is laid, When a high traverse frequency is employed, e.g. when approximately 20 wraps of yarn are placed on the container in a traverse stroke the helix angle will be in excess of, say, 1.

However, with a relatively low traverse frequency, the helix angle may he, say, V and ridging in this case is not pronounced. Similarly, with the international tilting of the axis of the ring of a ring and traveller yarn guide, with respect to the spindle axis, the helix angle usually will be of the order of 3 or above.

The ridging on the cheese packages counteracts any increase in package stability, due to the employment of a relatively high traverse speed, and increases the tendency of the yarn to slough, when it occurs. This is because the layers of yarn are not securely laid, at those points, and further, in this case and in the case of patterning on conically-ended packages, it may be the source of uncontrollable variations in the take-off tension of the yarn, and is, in any event, unsightly.

Further, with packages having ridging or patterning, the yarn thereon, if subject to retraction on the package, will be unevenly stressed while in the form of the package, and hence streaks may occur in the fabric into which such yarn is made up, as these stress differences are the cause of barre and are a cause of warp stripes in woven fabrics.

It has been known, with respect to cheese winding machines of the type in which the package is caused to be rotated by frictional contact with a grooved cylindrical driven traverse drum, or by a drive roll which also drives the traverse drum, the ridging of the yarn on the package in such a case being particularly obvious when it occurs during the winding of the package as compared to the type of cheese winding apparatus having a spindle and yarn traverse guide means which may be driven so that the speed of one is variable independently to the other at will and to which the present invention applies, to associate the most enhanced periods of such ridging with predetermined ratios of the reciprocating traverse yarn guide speed and the winding-on speed.

In these prior arrangements, the normal winding operation has been interrupted in a cyclic manner, by imposing a periodic variation on the winding-on speed continuously throughout the winding of a package, perhaps by applying a brake, or by causing the package to slip relatively to the traverse drum or drive roll.

It is an object of the present invention to provide winding apparatus including means to enable the winding operation to be programmed, and so to cause the patterning or ridging within a package to be reduced to negligible proportions, by eliminating, or at least reducing the extent of the occurrence of those wind ratios corresponding to the most enhanced patterning or ridging in the winding operation. I

As stated above, the periods of most enhanced patterning on comically-ended packages, and of ridging on cheeses, occur at predictable points'in the winding operation, these points being when the wind ratio is either a small integer or a ratio of small integers. In both cases, these points are associated with certain package diameters, the values of these diameters being calculable from a knowledge of the winding conditions pertaining to the formation of the package.

The wind ratios which correspond to the most enhanced patterning on conically-ended packages are as follows, given in an approximately order of decreasing magnitude of the effects:

1:1; 2:1; 3:1; 1:2, 3:2 and 5:2; 1:3, 2:3, 4:3, 5:3, 7:3 and 8:3; etc.

It will be appreciated that the numerical value of the wind ratio increases progressively as the package is being formed.

The above list is composed as a result of making the assumption, which will generally be true for conicallyended packages, that of the possible ratios, the integers 4:1 and above; and the simple fractions 7:2 and other multiples of 1:2; 10:3 and other multiples of 1:3 etc. will not occur in the winding of the package.

In order to reduce patterning to negligible proportions, the patterning associated with any of the wind ratios listed above should be eliminated, or substantially reduced in the winding of a package, and possibly also the wind ratios which are multiples of 1:4 up to 11:4.

With respect to cheeses, the wind ratios which correspond to the most enhanced ridging and which will generally occur in the winding of the package are: the inte gers 2:1; 3:1; up to 8:1; and the ratios of small integers in between these values.

According to the present invention, winding apparatus for producing cylindrically-wound packages, in which the yarn is laid with a relatively high helix angle, there being a predetermined point or points during the formation of such a package associated with a period or periods during which the package is patterned or ridged, each such period corresponding to winding conditions having associated therewith a Wind ratio (as defined above) the numerical value of which is either a small integer or a ratio of small integers, includes programming means arranged to control the winding conditions and to cause an increase in the numerical value of the wind ratio at the predetermined point or points in the winding operation, so as to reduce the extent of the period or periods of enhanced patterning or ridging in the formation of the package.

It will be appreciated that if a period of patterning or ridging is to be traversed effectively this could be in a manner which either caused the numerical value of the wind ratio to be either increased or decreased. However, if the value of the wind ratio is decreased, perhaps by a form of scrambling device, then the period of patterning or ridging associated therewith will have to be traversed again as the formation of the package continues, by causing the value of the wind ratio to increase. Hence if the value of the wind ratio is increased as each predetermined period of enhanced patterning or ridging is approached, then the periods will only have to be traversed once in each winding cycle.

Hence, over-end winding apparatus for producing conically-ended packages on a spindle in which package the yarn is laid with a relatively high helix angle, has programming means arranged to increase the speed of the spindle at the predetermined point or points in the winding operation, so as to reduce the extent of the period or periods of enhanced patterning in the formation of the package.

In one construction, the programming means for the spindle drive means includes a profiled cam arranged to make one revolution between the winding of successive packages, and embodying the desired spindle speed programme, the cam controlling the spindle speed in such a manner that at the selected points during the Winding of each package this speed is increased.

Conveniently, the programming means comprises an electrical device and includes a potentiometer, position of the slides of this potentiometer being controlled by the cam, and the output signal from the programming means controlling the output of a synchronous electric motor driving the spindle on which the package is formed, this motor only driving the spindle.

In addition, winding apparatus for producing cheeses having a rotating spindle, the rotational speed of the spindle being arranged to be proportional to the ratio of the yarn delivery speed to the package diameter, and reciprocating traverse yarn guide means the speed of which is variable independently of the spindle speed at will, and in which package the yarn is caused to be laid with a relatively high helix angle, has programming means arranged to decrease the speed of the traverse yarn guide at the predetermined point or points in the winding operation, so as to reduce the extent of the period and periods of enhanced ridging in the formation of the package.

According to another aspect, the present invention resides in a method of producing cylindrically wound packages, in which the yarn is laid with a relatively high helix angle, there being a predetermined point or points during the formation of each such package associated with a period or periods during which the package is patterned or ridged, each such period corresponding to winding conditions having associated therewith a wind ratio (as defined above) the numerical value of which is either a small integer or a ratio of small integers, comprises controlling the winding conditions to cause an increase in the numerical value of the wind ratio at the predetermined point or points in the winding operation, so as to reduce the extent of the period or periods of enhanced patterning or ridging in the formation of the package.

In one form, in a method for producing a conicallyended package on a spindle by over-end winding, and in which package the yarn is laid with a relatively high helix angle, the speed of the spindle is increased at the predetermined point or points in the winding operation so as to reduce the extent of the period or periods of enhanced patterning in the formation of the package.

In one method of winding comically-ended packages (particularly of the so-called long-to-short build), the spindle speed is arranged to be reduced throughout the winding of each package, except at the predetermined point or points, when the spindle speed is increased.

The program of the spindle speed may be such that optimum winding conditions are adopted where two features included in the programme are mutually inconsistent, the first feature being related to controlling the spindle speed so that this speed is increased at the predetermined point or points, and the second feature being related, say, to controlling the spindle speed so that this speed is reduced in a manner tending to maintain a constant value for the balloon tension of the yarn throughout the winding operation.

The allowable increase in spindle speed at any point in the winding operation will be limited, so that the winding-on tension in the yarn is not increased beyond an unacceptable level, or the change in winding-on tension is not so great as to render the properties of the yarn 'wound under this higher tension markedly different from the properties of adjacent layers of yarn, i.e. such that 7 it will be recognisable as streaks in the fabric into which the yarn is made-up.

However, a change in spindle speed from a value 10% aelow the normally-desired value at each predetermined point in the winding operation, to a value 10% above :his normally-desired value at each predetermined point, will generally have no recognisable adverse effects on the yarn or the fabric into which the yarn is made.

The increase in spindle speed at each predetermined point, and embodied in the spindle speed programme, may be arranged to be the minimum requisite value in Jrder to reduce substantially the patterning at that point in the winding operation, the value of the increase varying between different predetermined points.

In one arrangement the requisite increase in spindle speed at each predetermined point in the winding op- :ration is arranged to be effected during a period less :han 0.5% of the package winding period.

Alternatively, in a method of winding cheeses on a spindle in which the rotational speed of the spindle is arranged to be proportional to the ratio of the yarn deivery speed to the package diameter, and the speed of 1 reciprocating traverse yarn guide is arranged to be independently variable of the spindle speed at will, and n which cheese the yarn is laid with a relatively high 1elix angle the speed of the traverse yarn guide is de- :reased at the predetermined point or points in the windng operation, so as to reduce the extent of the period )r periods of enhanced ridging in the formation of the package.

Two embodiments according to the present invention and a modification thereof, will now be described by avay of example, but not limitation, thereof, and with reference to the accompanying drawings, in which- FIGURE 1 is a diagrammatic representation of a draw :wist machine for producing comically-ended packages 3y over-end winding,

FIGURE 2 shows one form of drive means for the nachine of FIGURE 1,

FIGURE 3 illustrates the cam used to control the spindle speed of this machine,

FIGURE 4 is a graph of the spindle speed programme :hroughout the winding of a package, when the winding apparatus is controlled by the cam of FIGURE 3.

FIGURE 5a shows the lay of the yarn on a conically- :nded package produced by the apparatus of FIGURE 1, when in a pattern-free condition.

FIGURE 5b shows the lay of the yarn on the package In a pattern-forming condition,

FIGURE 50 is a developed view of the lay of the package and indicates the helix angle associated with such a yarn package,

FIGURE 6 is a cross-sectional view of a modifiec Form of control device for the spindle drive means of the nachine shown in FIGURE 1,

FIGURE 7 shows diagrammatically a cheese winding irrangement according to the present invention in which :he traverse yarn guide is oscillated at a speed varying according to a predetermined programme,

FIGURE 8a shows, in an exaggerated manner, the ay of yarn on a cheese during a ridge-forming condition )f the winding apparatus of FIGURE 7, and

FIGURE 8b is a developed view of the lay of the yarn )f the cheese, and indicating the helix angle, 0 associrted therewith, this angle in practice being of the order f 1.

The apparatus shown in FIGURE 1 comprises a drawvwist machine for drawing a yarn made of a synthetic iolymer, for example, a polyamide, and for collecting he drawn yarn in the form of a comically-ended packtge by means of over-end winding.

The yarn 1 is withdrawn from a cheese 2 mounted on 1 container 3, and passes through yarn guide means, inlicated at 4, to a pair of co-operating feed rolls and 6. From these feed rolls the yarn is wrapped around an Cir inclined snubbing pin 7, which causes a considerable physical restraint to be imposed on the yarn, resulting in the yarn necking and being stretched to, say, five times its original length. The yarn then passes around draw rolls 8 and 9, which forward the yarn at a speed five times greater than it is forwarded by the feed rolls 5 and 6.

After the draw rolls 8 and 9, the yarn passes through a balloon guide 10 to the winding apparatus, where it is wound onto a package 11 rotatably mounted on a vertically extending spindle 12. The yarn guide means, casing the yarn to be laid on the package, comprises a conventional ring and traveller device 13 mounted on a ring rail 14, this ring rail 14 being reciprocated along the spindle axis by a known form of builder mechanism, including a striker plate 15 secured to the ring rail 14 for reciprocation therewith. At each end of each reciprocation stroke the plate 15 is arranged to operate a microswitch 16 or 17, and so causing the reversal of the direction of movement of the ring rail. The positions of the microswitches 16 and 17 are controlled respectively by two cams 18 and 19, rotatably mounted on a shaft 20 driven at a constant speed.

In the embodiment illustrated in FIGURE 1, the builder mechanism is adjusted so that a long-to-short package is produced, the distance between the microswitches, and consequently the stroke length of the reciprocation of the ring rail 14 along the package axis, continuously decreasing throughout the winding operation, the cams 18 and .19 rotating through 330 during the winding of each package.

In order to improve the stability of the package, the axis of the ring of the ring and traveller yarn guide device 13 is inclined at an angle of 3 to the axis of the spindle 12. Thus, the yarn is laid on the package in the form of closely-wound helical turns on which is superimposed a sinusoidal wave-form due to the inclination of the ring causing the traveller to have a small amplitude oscillating movement along the spindle axis. This sinusoidal component of the lay of the yarn on the package, causes the yarn to interlock, and so is less liable to sloughing, but does cause the yarn to form a surface relief pattern on the package at certain diameters as the package is being formed.

FIGURE 2 shows a convenient form of drive means for the draw-twist machine illustrated in FIGURE 1. This drive means comprises a synchronous electric motor driving a shaft 26 at a constant speed, this shaft being coupled to the feed rolls 6 and 7, and the draw rolls 8 and 9 of the machine. A second constant speed shaft 27 also is driven by the motor 25, and in turn drives a third constant speed shaft 28, through co-operating pinions 29 and 30.

The shaft 27 is coupled to a variable pitch pulley 32, and the spindle 12 is driven by the motor 25, through this variable speed device 32, shaft 33, and the shaft 27. The pitch of the pulley 32, and consequently the spindle speed, is controlled by the position of a lever 34 coupled to the variable pitch pulley 32. This lever 34 carries a cam follower 35 arranged to engage a cam 36 (shown in FIG- URE 3, but not shown in FIGURE 2), this cam 36 being rotatably mounted on the arm shaft 20, which is driven at a constant speed from the shaft 28.

Thus, the spindle speed is varied throughout the winding of a package in accordance to the profile of the cam 36, the spindle 12 being driven by the motor 25 via the variable speed device 32, which is controlled by the cam 36 through the cam follower 35 and lever 34.

The cam profile, which embodies the spindle speed programme throughout the winding of each package incorporates the features that the spindle speed reduces throughout the winding of each package, except at those points in the winding operation at which enhanced patterning of the package surface occurs these points corresponding to certain predictable package diameters. This feature of the spindle speed programme, being illustrative of the present invention, will be referred to in detail below, with reference to the data presented in the form of the graph comprising FIGURE 4.

The cam 36, illustrated in FIGURE 3, causes the spindle speed to be reduced from its initial high value, at40 on the cam profile, to its final, relatively low value at 41. There are three intermediate points 42, 43, and 44, which comprise protrusions on the generally-reducing radii of the cam, these points corresponding to points in the spindle speed programme at which the spindle speed is relatively sharply increased (but not instantaneously increased).

With respect to the feature of the Winding programme, that the spindle speed should be reduced during the winding of each package, of the possible types of build for comically-ended packages, with which the present invention is concerned, the long-to-short build, in which the ring rail has a continuously reducing reciprocating stroke length throughout the winding operation, is particularly advantageous when a reducing-spindle-speed programme is desired, as in this case the maximum productivity is possible from the winding apparatus.

With respect to the other comically-ended package builds limitations in speed are necessary as the package grows, due to the possibility of excessive torque being applied to the spindle, or the traveller of a ring and traveller yarn guide device exceeds its maximum desirable speed and is subjected to excessive wear.

The advantages are to be obtained if the spindle speed is reduced during the winding of a package are illustrated in the following example.

EXAMPLE A constant-spindle-speed device has a maximum acceptable rotational speed for a full package of 4.5 inches diameter on a 2 inches diameter container of 5000 r.p.m. If the device has a constant yarn delivery speed of 1,330 feet per minute, the traveller speed increases from 3,000 r.p.m. to 5,080 r.p.m. during the winding of the package.

The spindle-speed of the reducing spindle-speed apparatus, winding an equivalent package may start at 8,630 r.p.m. the yarn delivery speed being constant throughout the winding operation at 3,200 feet per minute, and the traveller speed being constant at 3,000 r.p.m.

Thus, winding apparatus with a reducing-spindle-speed device has increased productivity by over winding apparatus employing a constant spindle-speed throughout. Further, the traveller speed has been reduced by a maximum value of 41% and so reduced the possible stress within this part of the apparatus.

Further, the long-to-short package build, referred to above, also enables the balloon tension yarn and hence the yarn take-off tension to be controlled, is controlled, the balloon tension of the yarn being maintained substantially at a constant value throughout the winding operation if the spindle speed is arranged so that the square of the traveller speed is proportional to the package diameter as the package is being formed. Thus, the winding apparatus having a reducing-spindle-speed device may be programmed to achieve this desired object.

The graph shown in FIGURE 4 indicates a suitable spindle-speed programme for the production of a longto-short comically-ended packages of 70 denier multifilament yarn having 34 constituent filaments, the yarn being delivered at 1740 feet per minute. The graph is of spindle speed against package weight (this latter co-ordinate being converted to package diameter, as indicated by the axis 50), for a package of a particular overall length.

On this graph, the chain line 51 indicates how the spindle speed should be reduced in order to obtain a constant value of the balloon-tension of the yarn on the package throughout the winding operation, this value being 8 grams, or approximately the desired minimum value for maintaining a stable balloon, namely 0.1 gram per denier. As can be seen from FIGURE 4, in such a case the spindle speed decreases gradually throughout the formation of the package from an initial value of 9,200 r.p.m. to 7,200 r.p.m.

Superimposed on this curve 51 are three curves 52, 53 and 54, respectively, representing the three periods at which the most enhanced patterning occurs during the formation of the package, i.e. corresponding to a wind ratio of 1:2, curve 52 to a wind ratio 1:1, curve 53; and to wind ratio of 3:2, being indicated by curve 54.

Each curve is given by the general formula:

where S is the spindle speed (r.p.m.)

Del is the yarn delivery speed (inch/minute),

D is the package diameter (inch), and

P is the numerical value of the wind ratio. S=T+W, Where T is the traveller speed (r.p.m.)

It will be appreciated that, although the curve corresponding to each wind ratio is represented by a line, in fact patterning will occur on either side of this line, and each line represents the mean of a patterning zone on the graph.

At the points of intersection between the curve 51 and the curves 52, 53, 54, then the package wound according to the spindle speed programme embodied in the curve 51 will have enhanced surface patterning.

Consequently, in order to eliminate this patterning, or at least to reduce the extent to which it occurs, a revised winding programme is chosen, this programme being represented by the line 55 on the graph and embodied in the cam 36.

As can be seen from FIGURE 4, this Winding programme, and imposed by the cam 36 of FIGURE 3, initially, causes the yarn to be wound under the desired balloon tension of '8 grams, but gradually falls below this value, to a value of approximately 7 grams, when the first patterning zone is approached (corresponding to the wind ratio 1:2). The spindle speed is then relatively sharply increased by approximately 10%, indicated by the portion 56 of the line 55, causing the balloon tension to rise to 9 grams.

Thus, the patterning zone, is traversed quickly, compared to the winding programme embodied in the line 51 and say, during the laying of two layers of yarn on the package, for the surface relief pattern effect to be observed.

The spindle speed is then caused to be gradually reduced until the next patterning zone is encountered at 57 (corresponding to wind ratio 1:1). Intermediate between these two zones 56 and 57, the line 55 on the graph crosses the line 51 corresponding to the constant balloon-tension Winding programme, the spindle speed being caused to 'be reduced at a greater rate than that required for this latter programme. Thus the value of the balloon tension will have dropped from 9 grams to 7 grams during this period.

The patterning zone corresponding to the wind ratio 1:1 is traversed in like manner to that described above with reference to the wind ratio 1:2. Again, the spindle speed is relatively sharply increased, by approximately 10% (although it may be necessary to have a greater increase in the spindle speed in order to eliminate patterning at this point 51 in the spindle speed programme 55). The balloon tension again rises to about 9 grams in value.

This procedure is repeated with respect to the patterning zone corresponding to the wind ratio 3:2, the spindle speed being gradually reduced from the point 57, until it is at a value approximately 5% below the corresponding value on the constant balloon tension curve 51, at the point 58, it then being sharply increased to 5% above this value, and so the patterning zone is traversed, and

patterning is not formed on the package surface at this point 58 in the spindle speed programme 55.

It will be appreciated that with the Spindle speed programme 55 described above reducing the spindle speed throughout the winding operation, the intersection points 56, 57 and 58 between wind ratio curves 52, 53, 54 and the programme line 55 will occur at points corresponding to larger package diameters, compared to a programme requiring a substantially constant value for the spindle speed throughout the winding operation. Hence, it is relatively easier for the winding apparatus to be programmed so as to avoid the regions of enhanced patterning during the formation of packages.

During the winding of packages according to such a spindle speed programme 55, the rate of twist insertion in the yarn will fluctuate, but the overall value for this rate will vary only from approximately 0.25 t.p.i. at the initiation of the winding operation, to 0.17 t.p.i. at the outer layers of the package. Such a variation in the twist insertion rate will not be noticeable in the appearance of fabrics into which the yarn is made, particularly as the mean insertion rate is a low value, and hence the variations in the winding conditions embodied in this programme are normally acceptable.

To summarise, the steps taken in the preparation of a suitable spindle speed programme are as follows:

(1) Calculate the volume of the conically-ended package at various diameters, and plot a graph 50 of the diameter of the package against its weight,

(2) Calculate the spindle speeds required, for any given yarn delivery speed; in order to give a constant balloon tension throughout the package at the various diameters, and a graph 51 of spindle speed against package diameter plotted for constant balloon tension is obtained.

(3) The curves 52, 53, 54 associated with the wind ratios, corresponding to the periods of most enhanced patterning throughout the winding operation, are plotted at various spindle speeds and diameters, and are superimposed on the graph 51 prepared under paragraph 2, and the intersection points 56, 57, 58, respectively, are noted,

(4) Select a cam control device, and calculate the increase in package diameter per degree of angle of rotation of the cam, and

(5) Design a cam to suit the planned programme, which conforms to a line 55, and which causes the spindle speed to be increased comparatively sharply at the points, 56, 57, 58, but consistent with the attainment of the second feature of the spindle speed programme, the line 55 conforms to the graph 51 as closely as possible, optimum values, for the spindle speed being embodied in the spindle speed programme 55 at the points 56, 57, 58.

The cam 36, shown in FIGURE 3 has protrusions 42, 43, 44 respectively corresponding to the points 56, 57 and 58 in the spindle speed programme 55, the profile of the cam embodying the programme 55.

The appearance of the patterning on the surface of a conically-ended package, and the manner of its forma tion is indicated in FIGURE 5. As stated above, the yarn is laid on the package in the form of closely wound helical :urns on which is superimposed a sinusoidal wave form, when the axis of the ring of the ring and traveller yarn guide device is inclined to the spindle axis. The maximum angle of the inclination of the curve representing the developed view of the lay of the yarn on the package, to the mean axis of this curve, is herein defined as the helix angle, and is the angle (0) indicated in FIGURE 50. When the value of this angle is relatively high, say, in excess of 1, which it usually will be if the axis of the ring is intentionally tilted with respect to the spindle axis, then patterning of the package surface at certain package diameters occurs.

When each turn of yarn includes a small integral number of sinusoidal waves, i.e. the value for the wind ratio.

T :W being a small integer, or each turn of yarn has a number of sinusoidal waves which is a ratio of small integers, then the lay of adjacent turns of yarn is represented by FIGURE 5a. However, immediately on either side of this point in the winding operation, the parts of the waves having the maximum angle of inclination to the mean axis of the lay of the yarn on the package, i.e. the parts of the waves defining the helix angle (0) shown in FIGURE 5c merge together in the manner shown in FIGURE 512.

It will be appreciated that this merging of the turns of yarn causes ridges to be formed on the package surface, each ridge comprising only a small part of the length of each turn, and being inclined at an angle approximating to the helix angle (0) thereto. There may be more than one ridge associated with each turn of yarn, and in any event these ridges will be distributed over the package surface at this point in the winding operation, so that a fine surface relief pattern effect is obtained.

The yarn lay shown in FIGURE 5a corresponds to, say, a wind ratio of 1:1, while the yarn lay shown in FIG- URE 5b corresponds to a wind ratio of, say, 1.001: 1.

The numerical value of the wind ratio progressively increases throughout the winding operation; and in increasing the spindle speed at the points 56, 57, 58, referred to above, the numerical value of the wind ratio will be sharply increased at these points.

Care must be taken that in avoiding one region of patterning, the spindle speed programme is not such that the spindle speed increase ends in another zone of enhanced patterning, associated with a wind ratio which is either a small integer or a ratio of small integers.

The period taken to traverse any zone of enhanced patterning should be as short as possible. Thus at the predetermined points, for example, indicated at 56, 57, 58, the spindle speed programme should intersect the wind ratio curves 52, 53, 54, at an angle approaching a right angle.

The magnitude of the requisite spindle speed increase in order to traverse one of these patterning zones will vary with difierent wind ratios, but generally will be less than 20% of the mean value of the spindle speed at this point, although such an increase may cause an excessive increase in the balloon tension of the yarn. Hence, it may be desirable to accommodate a certain amount of patterning at certain points in the winding operation, so as to avoid unacceptable adverse effects due to other causes resulting from a large, relatively sudden increase in spindle speed.

The most enhanced patterning occurs when the wind ratio is a small integer, the most severe period corresponding to the wind ratio 1:1. With wind ratios comprising ratios of small integers, the patterning generally will not be as intense, nor as densely distributed over the package surface.

Such a sudden alteration in the spindle speed during a winding programme will have no marked adverse etfects on the fabric into which the yarn so-wound is made up, as the consequent increase in yarn Winding-on tension is acceptable in that the physical properties of the yarn are not appreciably affected by such a sudden change in the winding conditions. A change in the spindle speed of say, 20% may cause the balloon tension to alter by about 40%.

It will be appreciated that without making provision in the spindle speed programme to ensure that the balloon tension is maintained at a substantially constant value throughout the winding of each package, in the manner described above, the value of the balloon tension may vary over a wide range during the winding of such a package, for example, if the spindle speed is kept at a constant value, the balloon tension may change by as much as 250%.

In the over-end winding of conically-ended package, the wind ratios corresponding to the most enhanced periods of patterning of the package surface, in approximate order of severity of patterning are as follows:

1:1; 2:1; 3:1; 1:2, 3:2 and :2; 1:3, 2:3, 4:3, 5:3, 7:3 and 8:3.

In order to reduce the patterning to negligible proportions, all the patterning corresponding to the wind ratios listed above should be eliminated, or substantially reduced, and possibly also the patterning corresponding to the wind ratios which are multiples of 1:4 up to 11:4. The Wind ratios which are multiples of 1:5; 1:6; etc. are of relatively minor, importance and may be ignored, although clearly a further improved package would be obtained by the elimination of, or the reduction in the extent of, some, or all, of these wind ratios.

It is necessary to make a small correction to the equation S=T+W, given above, if strict accuracy is to be observed. Firstly, account must be taken of any yarn retraction on the package after it has been wound, if this yarn is of synthetic polymeric material which is subject to this effect.

Such retraction of the yarn causes the package as a whole to retract, and so relevant changes in package diameter will occur.

In addition, in comically-ended packages in which the yarn lay is in the form of closely-wound helical turns having superimposed thereon a sinusoidal motion, account must be taken of this sinusoidal component of the winding motion in predetermining the values of the package diameters at which enhanced patterning is to be expected.

In this way an error of approximately 4% in the calculated value for the package diameter may occur.

Conveniently the profile of the cam 36 is adjustable (or conforms to that of an adjustable cam), so that the desired spindle speed programme may be determined initially in an empirical manner.

The basic profile of such an adjustable cam would be such that the speed of the spindle of the winding apparatus is reduced during the winding of a package, except where knuckles are displaceably attached to the surface of the cam, the spindle speed being increased when the cam-follower engages these knuckles. The cam should be profiled so that at a position mid-way between adjacent knuckles the spindle speed is such that the desired balloon tension is maintained in the yarn, while at the position immediately before the engagement of a knuckle the spindle speed is, say, below the value required in order to give this desired balloon tension at that position.

These knuckle positions coincide with the points in the winding operation when the most enhanced patterning of the package surface occurs.

The effect of each knuckle is to cause the spindle speed to rise rapidly, from this value below, to the same value above the spindle speed required to maintain this desired balloon tension. The spindle speed is then arranged to fall gradually before engaging the next knuckle, to a value corresponding to a balloon tension 10% below the predetermined value at the point corresponding to this next successive knuckle.

The positions of the knuckles are deter-mined during the initial setting-up of the apparatus.

As stated above, knuckle positions can best be determined empirically, rather than by determining the ab solute values for the traveller speed or winding-on speed or even by a determination of the relevant package diameters, a knuckle being secured to the cam profile where patterning is observed during the previous production of a yarn package.

It may not be necessary for the spindle speed to be increased by as much as 20% at the patterning points so as to reduce effectively the extent of the patterning, although a spindle speed change as low as 6% may prove to be satisfactory, in the case of the patterning conditions associated with certain of the points defined above. Thus knuckles of various heights are used, the height of each knuckle corresponding to the spindle speed change required at that point in the winding operation.

Instead of the variable-pitch pulley and cam arrangement described above, other forms of programming means, for example, electrical or electronic devices may be employed, for example, by having a main motor for the draw rolls etc. and a separate motor for the spindle, the programming means being associated with this latter motor, so as to control the spindle speed in the desired manner. However in each form, when patterning is encountered, the spindle speed is arranged to be increased so that the patterning condition is passed through quickly and, hence, its effect either to be reduced or eliminated.

A modification of the winding apparatus of the draw twist machine described above includes a different form of device for controlling the spindle speed in accordance with the programme embodied in the cam 36 of FIG- URE 3.'This control device 60 is electrical in form and is illustrated in FIGURE 6, and will now be described, those parts which are identical to corresponding parts described above being given the same reference numerals, and will not be referred to again except Where necessary for an understanding of the manner of operation of this modification.

In this arrangement the spindle 12 is driven by a synchronous DC. motor (not shown), individually of the main drive means which drives the draw rolls and feed rolls of the draw twist machine.

The current supplied to the DC. motor is controlled by a reference voltage from a linear potentiometer 61, the slider 62 of which is rigidly secured to the cam follower 63 of the programming cam 35. Thus, the spindle speed is varied as in the previously described embodiment, the value of the spindle speed being determined by the position of the slider 62 of the potentiometer '61 the output of which is connected to the DC. motor by a lead 64.

Conveniently the reference voltage from the potentiometer 61 is compared with that obtained from a tacho-generator connected to the output shaft of the DC motor.

The error signal obtained by this comparison is then used to alter the setting of the D.C. motor.

Trimming rotary potentiometers (not shown) may be provided at either end of the linear potentiometer '61, each having a range of approximately 20% of the linear potentiometer range, and are used to control the range of the linear potentiometer.

This control arrangement for the Winding apparatus is of particular application Where it is required to control also the start-up and slow-down performance of the draw twist machine, during the production of each yarn package, in order to reduce yarn breakages, which are more likely to occur at these points in the winding of a package, than intermediate therebetween.

Thus an electrical timer may be included in the apparatus so that the draw rolls are not operably connected to the drive means until say, 4 seconds, after the spindle has been so connected.

A second timer which controls the slow-down performance of the draw twist machine may also be provided. In such an arrangement a tacho-generator monitors the speed of the main drive means motor, and feeds back a signal to the DC. motor to drive it against brake pressure acting on the spindle during the slow down of the machine. Thus both motors slow down with speeds which are a predetermined ratio of each other, the draw-rolls slowing down freely and the timing of the application of the brake to the spindle is controlled so as to maintain a traveller speed of at least 2,000 rpm.

A cheese winding arrangement according to the present invention is shown in FIGURE 7. This arrangement comprises a synchronous electric motor the output shaft 71 of which drives a spindle 72 on which the cheese 73 is being formed, the cheese container 74 being clamped to the spindle 72 in any convenient way.

Conventional traverse yarn guide means, indicated generally at 75, comprises a reciprocating yarn guide 76 in the form of an open-ended notch, and is driven by a secand synchronous electric motor 77, via a variable pitch pulley arrangement, shown at 78, the traverse guide speed being varied in accordance with the profile of a control :am (not shown).

The yarn is delivered to the yarn guide at a constant speed from a feeding device (not shown) and hence the speed of the output shaft 71 of the motor 70, and the rotational speed of the package 73 is arranged to be con- :inuously reduced throughout the winding of each package, as the cheese diameter increases. To arrange that the winding-on speed of the yarn is identical to the yarn delivery speed, and there is no build up of tension within the yarn, a conventional sensing head 80 is positioned in the yarn path, the output of which head controls the output of the motor 70 via a known form of servo-device, indicated diagrammatically at 81.

The appearance, and manner of formation of ridging 3n cheeses, is indicated in FIGURE 8a, which shows in an exaggerated way the lay of the yarn on a cheese. For the sake of clarity, the angle of lay of the yarn has been increased, the value of this angle, normally being of the order of 1. As illustrated in FIGURE 8b this angle is also equal to the helix angle as defined herein, ridging being pronounced on cheeses at certain package diame- :ers throughout the winding operation when this angle is in excess of 1, but will not be so enhanced when the "helix angle 0 is about, say,

In FIGURE 8a the lay of the yarn on the cheese when the wind ratio is, say, 2:1 is shown, this being when the :raverse yarn guide executes one oscillation along the spindle axis per two spindle revolutions and synchronisation of the winding occurs.

Under such winding conditions the yarn of one layer is laid on top of yarn laid in the layers immediately previously, and a ridge of yarn is formed along the whole length of each layer.

However the yarn will not be so laid, in the form of ridges, when the speed of the traverse yarn guide is vared, or the package diameter alters so that the wind ratio l.995:1 or 2.005:1.

Care must be taken to ensure that a wind ratio corresponding to a period of enhanced ridging does not occur tear to the outside of a completed cheese, or that the de- :rease in traverse guide speed included in the winding arogramme, is not such that the one period of enhanced idging is avoided but another period is entered immeliately afterwards.

It will be appreciated that, whereas for over-end winding of comically-ended packages any change in the traveler speed will substantially affect the winding conditions, ;uch that it is desirable that the traveller speed should be ncreased rather than decreased during the winding op- :ration, with cheese winding the winding conditions are ess sensitive to changes in the traverse yarn guide speed, ind consequently this speed conveniently may be de- :reased or increased during the winding operation.

As in the case of over-end winding, a reduction in the lam traverse guide speed will imply that the patterning zone occurs at relatively larger package diameters than if his speed is increased. Consequently, by decreasing the Jam traverse guide speed it may be possible to avoid the )atterning regions in a cheese of a predetermined size.

However, if the period of patterning is traversed by in- :reasing the traverse guide speed, then this period will lave to be traversed again at a larger package diameter, Jy decreasing the traverse guide speed, so no advantage s gained.

The wind ratios corresponding to a period of enhanced 'idging, and normally encountered in the winding of :heeses are the integers 2:1 up to 8:1 and the ratios of small integers in between these values.

Again, the determination of the points in the cheese 16 winding operation at which ridging occurs, is best done in an empirical manner.

When the relevant package diameters have been determined, the method of programming the winding apparatus will be identical to that described above with reference to the formation of conically-ended packages by over-end winding. The cam embodying such a cheese winding programme will resemble the cam 36 illustrated in FIGURE 3.

Winding apparatus according to the present invention, including means for increasing the spindle speed at predetermined points during the winding operation of each package, may include also means for scrambling the spindle speed, which means also will tend to eliminate ridging or patterning.

Account may have to be taken, in this respect, according to whether the yarn being wound is either a monofilament or a multifilament yarn.

In each illustrated arrangements, the increase in the speed of the spindle (or the yarn traverse guide device) will be relatively fast compared to the overall time required to wind each package, for example, a spindle speed increase of, say, 1000 rpm. being made in less than 0.5% of the package winding cycle, say, in 7.5 seconds.

It is essential that at the time in the winding operation at which the increase in spindle speed (or traverse guide speed) is initiated by the programming means, that it is within 1% of the predetermined programme for the winding apparatus.

In each embodiment described above, the accuracy with which the programme embodied in the cam is reproduced by the winding apparatus, is mainly dependent upon the accuracy of the motor controlled by the cam, and this will normally be of the order of /2 What we claim is:

1. Apparatus for producing a cylindrically-wound yarn package on a spindle, in which package the yarn is laid with a helix angle in excess of one degree, there being predetermined points during the formation of such a package associated with periods during which the yarn turns merge together to form ridges, each period of enhanced ridging corresponding to winding conditions having associated therewith a wind ratio the numerical value of which is either a small integer or a ratio of small integers, including programming means having a profiled cam which makes one revolution between the winding of successive packages and embodies the desired spindle speed program whereby the winding conditions are controlled and caused to produce an increase in the numerical value of the wind ratio at predetermined points in the winding operation so as to reduce the extent of the periods of enhanced ridging in the formation of the package.

2. Apparatus having over-end winding guide means, and for producing a comically-ended yarn package on a spindle, in which package the yarn is laid with a helix angle in excess of one degree, there being pre-determined points during the formation of such a package associated with periods during which the yarn turns merge together to form a surface relief pattern effect, each period of enhanced patterning corresponding to winding conditions having associated therewith a wind ratio the numerical value of which is either a small integer or a ratio of small integers, which includes programming means having a profiled cam which makes one revolution between the winding of successive packages and embodies the desired spindle speed program whereby the Winding conditions are controlled and caused to produce an increase in the spindle speed at the pre-determined points in the winding operation, so as to reduce the extent of the periods of enhanced patterning in the formation of the package.

3. Apparatus as claimed in claim 2 in which the programming means comprises an electrical device, and includes a potentiometer, the position of the slider of this potentiometer being controlled by the cam, and the output signal from the programming means controlling the spindle speed.

4. Apparatus for producing a cheese on a spindle, and including a reciprocating yam traverse guide, the rotational speed of the spindle being arranged to be proportional to the ratio of the yarn delivery speed to the package diameter, and the speed of the traverse yarn guide being variable independently of the spindle speed at will, and in which cheese the yarn is laid with a helix angle in excess of one degree, there being pre-determined points during the formation of such a cheese associated with periods during which the yarn turns merge together to form ridges, each period of enhanced ridging correspond ing to winding conditions having associated therewith a wind ratio the numerical value of which is either a small integer or a ratio of small integers, which includes programming means having a profiled cam which makes one revolution between the winding of successive packages and embodies the desired spindle speed program whereby the winding conditions are controlled and caused to produce an increase in the numerical value of the wind ratio at pro-determined points in the winding operation, and thereby reduce the extent of the periods of enhanced ridging in the formation of the package.

5. A method of producing a cylindrically wound yarn package on a spindle, in which package the yarn is laid with a helix angle in excess of one degree, there being predetermined points during the formation of such a package associated with periods during which the yarn turns merge together to form ridges, each period of enhanced ridging corresponding to winding conditions having associated therewith a wind ratio the numerical value of which is either a small integer or a ratio of small integers, which comprises controlling the winding conditions to cause an increase in the numerical value of the wind ratio at the predetermined points in the winding operation, so as to reduce the extent of the periods of enhanced ridging in the formation of the package.

6. A method of producing a conically-ended yarn package on a spindle, in which package the yarn is laid with a helix angle in excess of one degree, there being predetermined points during the formation of such a package associated with periods during which the yarn turns merge together to form a surface relief pattern elfect, each period of enhanced patterning corresponding to winding conditions having associated therewith a wind ratio the numerical value of which is either a small integer or a ratio of small integers, which comprises controlling the speed of the spindle to cause an increase in the spindle speed at the predetermined points in the winding operation, so as to reduce the extent of the periods of enhanced patterning in the formation of the package.

7. A method as claimed in claim 6 in which the spindle speed is arranged to be reduced intermediate between the predetermined points.

8. A method as claimed in claim 6 in which the increase in spindle speed at each predetermined point is arranged to be less than 20% of the mean value of the spindle speed at that point in the winding operation.

9. A method as claimed in claim 6 in which the increase in spindle speed at each predetermined point, and embodied in the spindle speed program, is arranged to be the minimum requisite value in order to avoid patterning at that point in the Winding operation, the value of this increase varying between different predetermined points. a

10. A method as claimed in claim 6 in which the requisite increase in spindle speed at each predetermined point in the winding operation is arranged to be effected during a period less than 0.5% of the package winding period.

11. A method of producing cheeses on a spindle, in which the rotational speed of the spindle is arranged to be proportional to the ratio of the yarn delivery speed to the package diameter, and the speed of a reciprocating traverse yarn guide is arranged to be independently variable of the spindle speed at will, and in which cheese the yarn is laid with a helix angle in excess of one degree, there being predetermined points during the formation of such a cheese associated with periods during Which the yarn turns merge together to form ridges, each period of enhanced ridging corresponding to winding conditions having associated therewith a wind ratio the numerical value of which is either a small integer or a ratio of small integers, comprises controlling the speed of the traverse yarn guide to cause an increase in this speed at the predetermined points in the winding operation, so as to reduce the extent of the periods of enhanced ridging in the formation of the package.

References Cited UNITED STATES PATENTS 3,009,308 11/1961 Bromley et a1. 57-55.5 3,137,987 6/1964 Potts 57S5.5 3,334,828 8/1967 Harrison 24226.1 2,529,559 11/1950 Kreamer.

2,764,363 9/1956 Stammwitz 242-26.3 3,130,930 4/1964 Miller 242-263 JOHN PETRAKES, Primary Examiner US. Cl. X.R.

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