US3445999A - Method and apparatus for producing yarn packages with a variable speed spindle - Google Patents

Description

May 27, 1969 J. R. DE RUIG 3,445,999 METHOD AND APPARATUS FOR PRODUCING YARN PACKAGES WITH A VARIABLE SPEED SPINDLE Filed March 15, 1967 Sheet of2 IN VENTOR ATTORNEYS May 27, 1969 J. R. DE RUIG 3,445,999 METHOD AND APPARATUS FOR PRODUCING YARN PACKAGES WITH A VARIABLE SPEED SPINDLE Filed March 15, 1967 Sheet 2 of 2 INVENT OR j mywmaw ATTORNEYS United States Patent 3,445,999 METHOD AND APPARATUS FOR PRODUCING YARN PACKAGES WITH A VARIABLE SPEED SPINDLE Jan Robert de Rnig, Arnhem,

American Enka Corporation, tion of Delaware Filed Mar. 15, 1967, Ser. No. 623,278 Claims priority, application Netherlands, Mar. 18, 1966, 6603529, 6603530 Int. Cl. B65h 54/02; B01h 13/00 US. CI. 57-94 Netherlands, assignor to Enka, N.C., a corpora- 46 Claims ABSTRACT OF THE DISCLOSURE This invention relates to method and apparatus for producing yarn packages and more particularly packages of drawn yarn by the use of a winding apparatus comprising at least one winding spindle on which the yarn is wound into a package, the winding spindle being driven at a rotary speed which is varied in a programmed manner as a function of a variable v which represents the growth of the yarn package. One aspect of the invention is particularly concerned with producing yarn packages by winding of the yarn, and another aspect of the invention is particularly concerned with producing yarn packages by twisting and winding of the yarn.

Heretofore a method has been proposed in which a yarn is, on a drawtwisting machine, successively drawn, twisted, and wound on a variable speed winding spindle. This method is disclosed by French Patent No. 1,385,792.

It will be recognized that drawing takes place in a zone bounded by a pair of feed rollers and a draw roller. The ratio of the peripheral speed of the feed rollers to that of the draw roller is referred to as the draw ratio. With the known apparatus described in the above-mentioned patent twisting is done by the ring twisting method, by which the yarn, via a top eyelet and a ring-guided traveller, is wound on to a yarn support to form a yarn package. Between the top eyelet and the traveller the yarn forms into a balloon. The complete process or method carried out on the drawtwisting machine for producing one yarn package will hereinafter he referred to as the doff or winding operation used to draw the yarn from its source.

The further development of drawtwisting machines has been especially directed towards increasing the draw rate without impairing the quality of the processed yarn. Thus, if an increase in draw rate should lead not only to an increase in production, but also to a yarn having a lower quality, then difficulties would be encountered in the further processing of the product and/or a high percentage of inferior-quality material would be obtained. By the known method in which time is the process variable, the rotary speed of the winding spindle is therefore so programmed that at a relatively high draw rate the balloon tension is maintained at constant acceptable value during the doif, and that at the end of the dolf the traveller speed is still acceptable. The course, that is, the programmed variation, of the spindle speed is controlled by a programming unit, in which there is a programme carrier in the form of a programme storing card. The programme carrier is displaced at a constant rate by a driving element and provides the set value for an automatic control loop of which the driving mechanism for the winding spindle forms a part. In this control loop the actual speed of the winding spindle is compared with the set value, which represents the desired spindle speed. When there is a difference between the two speeds, a correction is applied which reduces said difference.

The known method has the disadvantage that it is only suitable to be used for one particular value of the draw rate, which for convenience, will hereinafter be referred to as programme draw rate. If the draw rate should be different from this programme draw rate, it would in the first place be necessary, assuming other conditions to be equal, to execute the programme in a correspondingly shorter or longer period of time, depending on whether the draw rate is higher or lower than the programme draw rate. Although this problem could be solved in part by displacing the programme carrier at a correspondingly higher or lower rate, there is a second and more serious disadvantage. Thus, it has been found that when use is made of a diiferent value for the draw rate and the duration of the programme is merely prolonged or shortened correspondingly, the course of the balloon tension becomes difierent from the course occurring at the programme draw rate. If, for instance, the balloon tension during the doff is constant at the programme draw rate, it will no longer be constant at the modified draw rate. This indicates that if it is desired to modify the draw rate V, while the course of the balloon tension is to be kept unchanged, a different programme will be required for the programming unit. This programme must there fore specifically be adapted to the desired draw rate and the desired course of the balloon tension.

It will also be appreciated that the drawtwisting process is governed not only by the draw rate, but also by parameters such as twist, linear density of the yarn, length of yarn to be accommodated in the package, shape of the yarn package, and type of yarn processed. Each of the quantitative parameters of said series must be capable of assuming a sufiicient number of values, and it must also be possible to use a variety of package shapes and types of yarn. It will be clear that if the drawtwisting apparatus is to satisfy widely varying requirements as far as these parameters are concerned, a large number of programme storing cards must be available. Let us, for instance, assume that the known drawtwisting apparatus as shown by the French patent is to process one and the same type of yarn to yarn packages, and also that for each of the parameters draw rate, twist, linear density and yarn parameters in any combination, then the required number of programme storing cards is 5 :625. It will, therefore, be clear that when as in the above example it is to be possible to choose from only five different draw rates, the required number of programme storing cards rises from 5 to 5 =625, which means an increase of 500 programme storing cards.

The disadvantage of requiring a large number of programme storing cards is not only encountered when it is desired to maintain a particular course of the ballon tension during the doff. For example, when the traveler rings of a drawtwisting apparatus which operate by the ring twisting method are positioned inclined relative to the winding spindles, the package build-up presents the same problem as in the case of winders, namely the occurrence of mirror patterns in some yarn layers. In this situation, in addition to the main transverse motion of the ring rail or spindle-carrying bar there is also a subtraverse motion resulting from the inclined position of the traveller ring. The traveller acts as if it were a revolving transverse member making a traverse stroke which is governed by the diameter of the traveller ring and the angle through which it is inclined. The traverse speed is governed by the speed of the traveller.

When at a given moment during the doff the number of wraps laid on the yarn package per unit time is an integral multiple of the traveller speed at that particular moment, then the yarn wraps will be laid on the package contigious or at least very close together. With winding machines this phenomenon is known as mirror pattern formation. Since the speed of the main traverse is many times smaller than that of sub-traverse, the main traverse has only a small influence on the mirror pattern formation. Furthermore, mirror patterns are also formed if the traveller speed is an integral multiple of the number of yarn wraps laid per unit of time.

By appropriately programming the speed n of the winding spindle the formation of mirror patterns can be prevented. To this end, it is required that during the doff the speed of the winding spindle passes through such values that neither the quotient nor the reciprocal value thereof can be an integer; n, being the speed of the traveller.

If the method indicated as known should, with the necessary changes being made, be used for winding mirror-free yarn packages, then it is again necessary to use a different programme storing card as soon as the draw rate is changed, say, from V to V This must be done because, as a result of the draw rate being changed, there is a chance for mirror pattern formation with other combinations of the values 11 and the yarn package diameter d. In other words, for one particular value of n and two different values V and V of the draw rate, the values of d at which mirror patterns are formed are different for the two cases. So if at the draw rate V the spindle speed n should, as a function of the package diameter d, pass through the same values as at the draw rate V,,, then the chance of mirror pattern formation is not fully obviated. Also in this case, it is therefore not sufficient merely to adapt the duration of the programme of the programming unit to the draw rate.

It will further be appreciated that when use is made of a constant draw rate, as is the case in the know method, the twist in the yarn will vary as a result of the variation in the speed of the winding spindle. This in itself is not objectionable, because the twisting in this stage generally only serves to give the yarn some coherency. If necessary and if possible, however, the draw rate may be varied proportionally, although the processing speed of the yarn is consequently no longer constant.

It should also be recognized what is to be understood by the term twist. If use is made of the ringtwisting process, then the twist T in a given yarn portion satisfies the following formula:

T 1 1rd where d is the yarn package diameter at which the given yarn portion is positioned. The total twist T in this yarn portion is then,

where 11 represents the speed of the winding spindle the moment this yarn portion is laid on the yarn package. The total twist defined by this summation will hereinafter be referred to as the twist T. It should be borne in mind that T is equal to 11 V only if the yarn is drawn off overhead from the package. If the yarn is drawn off in tangential direction, then, T=T =n l V.

The setting of a different twist at a given draw rate V, indicates, therefore, the choice of a different speed n for the winding spindle. If the speed n is variable, then it is required to choose a different range within which it will be varied. With the known method this calls for the use of a different programme storing card each time a yarn with a different twist is to be wound. As heretofore noted, the programme is also dependent on parameters such as the draw rate, the linear density, the length of the yarn to be accommodated in the yarn package, the geometric shape of the yarn package, and the type of yarn. Therefore, there will be a need for a great many different programmes, and consequently storing cards with the known drawtwisting method and apparatus.

Advantageously the present invention substantially reduces the number of programmes required for producing yarn packages by winding in such drawtwisting methods.

Thus this invention contemplates a programmed method for producing yarn packages at many different yarn feed rates without changing a preselected programme in which a variable speed spindle is used to wind yarn into a package, which comprises feeding the yarn to the variable speed spindle, winding the yarn on the spindle in a programmed manner whereby the peripheral speed of the resulting yarn package is equal to the yarn feed rate and controlling the speed of the spindle in accordance with a preselected programme as a function of a process variable representing the growth of the yarn package, said programme being preselected to be independent of the yarn feed rate and to automatically adapt the speed of the spindle to variations in the yarn feed rate.

Furthermore, this invention also contemplates an apparatus for producing yarn packages in accordance with the above-mentioned programmed method, which comprises a variable speed winding spindle on which the yarn is wound into a package, means for feding a yarn to said winding spindle at many different rates, programming means for controlling the rotary speed of said variable speed spindle in accordance with a preselected programme as a function of a process variable representing the growth of the package, whereby the peripheral speed of the resulting yarn package is equal to the yarn feed rate, said programme being preselected to be independent of the yarn fed rate and to automatically adapt the speed of the spindle to variations in the yarn feed rate.

One aspect of the invention is directed to a programmed method for winding yarn in which there is provided in the programme, a programmed quantity which, as a function of the process variable v, passes through values each of which is proportional to the rotary speed n (v) of the winding spindle required at the corresponding value of the variable and at a particular feed rate V of the yarn fed to the winding apparatus, at control quantity is formed which is proportional to the applied feed rate V of the yarn, a product V.n (v)/V is formed, and from this product the value n(v) of the rotary speed of the winding spindle required at the feed rate V is derived.

It will thus be appreciated that in this manner, this proposed method has the advantage that the rate at which the yarn is fed to the winding apparatus no longer influences the choice of the programme. In the case of, for instance, a drawtwister this implies that if the draw rate is changed, the programming unit need not, as in the case of the heretofore known method, be provided with a different programme.

Any operation which leads to the product V.n (v)/V may be applied. Thus, the speed n (v) may be included in the programme, and subsequently the quotient V/V be formed which is finally multiplied by the programme value n (v). Or the course of n (v) included in the programme may first be divided by V and the resulting quotient multiplied by V.

In accordance with this aspect of the invention prefer ence is given to a method characterized in that in the programme there is included a programmed quantity proportional to the quotient ln (v)/V a control quantity proportional to the applied feed rate V of the yarn fed to the winding apparatus is formed, the product ow) V- is formed, and from this product the value n(v) of the speed of the winding spindle required at the feed rate V is derived.

In this case only a multiplication is required in order that the desired value ew) T, of the speed of the winding spindle may be formed.

This method for winding yarn may be carried out in several ways. For instance, the feed rate of the yarn can be measured by passing the yarn over a low-friction pulley or the like, of which the angular velocity is measured. However, for delicate yarns contact with any member that introduces an additional friction is undesirable. Moreover, a slip-free drive of the pulley is diflicult to realize.

An effective method for winding yarn in which the yarn is drawn in a continuous manner on a drawing apparatus provided with at least one feed roller and one draw roller, and subsequently wound by a winding apparatus, and more particularly for the draw-twisting of a yarn, is characterized in that the control quantity that is proportional to the feed rate of the yarn is derived from one of the rollers of the drawing apparatus.

This solution makes it unnecessary for the yarn to contact any additional member for the purpose of measuring the feed rate. Moreover, the provisions normally made with drawing apparatus to prevent slippage of the yarn insures that the angular velocity of the roller chosen is a precise measure of the speed of the yarn passed over said roller.

It will also be appreciated that the above-mentioned control quantity may be derived from the feed roller.

However, it is preferred to derive the control quantity that is proportional to the feed rate of the yarn from the draw roller. In this manner, if the draw rate is left unchanged, and the draw ratio is changed, the programme can be executed in the same way. But if the execution of the programme should be controlled by the feed roller, the rotary speed of the winding spindle would become lower or higher depending on whether the draw ratio should be decreased or increased.

It is further preferred to use a method for winding yarns in which a control quantity is formed which is proportional to the rate at which the yarn is fed to the winding apparatus, and that this quantity controls the execution of the programme, so that the programme is executed in a period of time which is proportional to the feed rate of the yarn. In this way it is insured that the programme is executed at a rate that corresponds to the feed rate of the yarn.

This invention also is directed to an apparatus for winding a yarn, more particularly a drawn yarn, which comprises at least one winding spindle on which the yarn may be wound into a package, and a programming unit, the winding spindle driving the package, during the formation thereof, at a rotary speed which is varied as a function of a variable v which represents the growth of the package, in accordance with a particular programme under the control of the programming unit. This apparatus is preferably further characterized as having a programming unit which includes a programmed quantity proportional to the quotient n (v)/ V and having a first means for forming a control quantity proportional to the yarn feed rate V to be applied, and for forming the product 0( To and a second means for adapting the rotary speed of the Winding spindle to the value of said product.

Furthermore, this apparatus is preferably so constructed that the first means comprise a pulse source which emits pulses the repetition frequency of which is proportional to the feed rate of the yarn, and a pulse divider to which the pulses are applied, the repetition frequency of the pulses emitted by the pulse divider being set under the control of the programming unit in accordance with the programmed quantity.

With this apparatus the influence of the yarn feed rate on the desired course of the rotary speed of the winding spindle is eliminated from the programming unit. The programming unit can bring the repetition frequency of the pulses emitted by the pulse divider to such a value that the repetition frequency represents the desired course of the spindle speed at the set feed rate. By having the drive of the winding spindle controlled by the pulses from the divider the speed of the winding spindle can be made to follow the desired course. It will be clear that the control quantity that is proportional to the feed rate of the yarn is represented then by the repetition frequency of said pulses. The programmed quantity is represented in this case by the reciprocal value of the frequency division. The use of a pulse source has the advantage that the relation between the feed rate and the frequency of the pulses may in a relatively simple manner be brought to the desired accuracy. To this end, it is suflicient for the number of pulses emitted per unit length of the yarn passed to be adapted to the desired accuracy. Moreover, a factor that contributes to the accuracy is that the relation between the input quantity and the output quantity of the pulse source, in this case the relation between the feed rate and the repetition frequency of the pulses, is independent of influences of temperature, ageing, and the like, which may have a disturbing effect in the case of analogue transducers.

A pulse generator may be used as a pulse source which independently generates pulses having a repetition frequency that may be manually set in dependence on the yarn feed rate used. However, in such a case adjustment to a difli-cult frequency always requires a separate operation. It is preferred to use an embodiment in which the generated pulses are derived from the yarn itself. To this end, the yarn may be passed over a low-friction pulley or the like that forms part of a pick-up element which emits pulses having a repetition frequency proportional to the angular velocity of the pulley, and hence to the yarn feed rate. However, such a pulley forms another machine part for the yarn to get into contact with.

In this regard, an embodiment of the apparatus which is particularly advantageous, is one in which the yarn is drawn on a drawing device that is at least provided with one feed roller and one draw roller, and is subsequently wound into a package on a winding device, more particularly a drawtwisting apparatus, and which is characterized in that the pulse source is formed by a pick-up element coupled to one of the rollers of the drawing apparatus. In this way the yarn, which is often delicate, need not be in contact with an additional machine part.

The most advantageous embodiment is obtained when the pulse source is formed by a pick-up element that is coupled to the draw roller.

In principle, the pulse source may be an electromechanical pulse source, in which an electric contact is mechanically opened and closed under the influence of the yarn motion. However, for the usual high yarn speeds it is preferred to use pulse sources in which pulses are generated by photoelectric, inductive or capacitive means.

As previously mentioned, the duration of the programme of the programming unit must be adjusted when the yarn feed rate does not correspond to the programme draw rate. This may be done by an operator. The operator must then always choose from the programme such a value as corresponds to the prevailing value of the variable that represents the growth of the package. This variable may be the time, or the diameter of the yarn package.

A preferred embodiment of the apparatus, which does not require the attendance of an operator, is characterized in that means are provided for the formation of a control quantity which is proportional to the rate at which the yarn is fed to the winding apparatus, and in that there is provided a control element through which the programming unit is controlled by this control quantity, so that the programme is executed in a period of time that is proportional to the feed rate of the yarn. It will be appreciated that the control quantity, which is multiplied by the programmed quantity, may be used for this purpose.

The programme will often be stored in a programme carrier, such as a magnetic tape, a magnetic disk, a punched tape or a programme storing card. It is also possible for the programmed quantity to be represented, for instance, by an electric voltage which is varied by contacts being opened and closed in a particular configuration controlled by a memory. In all these cases the control element controls the speed at which the programme is executed. When a programme carrier is used which, during the execution of the programme, carries out a movement relative to a sensing device, then the control element may be used to effect this movement.

In one suitable embodiment of the apparatus, a pulse source is provided for applying pulses to the control element, which have a repetition frequency that forms the control quantity proportional to the yarn feed rate. This apparatus is particularly suitable when the programme is made up of a number of parts, each of which corresponds to a discrete value of the speed of the winding spindle. However, it is also possible, with the aid of a digital-toanalogue converter, to convert the pulses into a continuous movement of the programme carrier. When the apparatus is to be used for winding a drawn yarn and is provided with at least one draw roller, then it is preferred to couple the last-mentioned pulse source to the draw roller. It is further preferred that an electric stepping motor is used as the control element.

It is also necessary for the duration of the programme to be adapted to the length of yarn to be wound into the package. When a drawing apparatus is used this may be effected, for instance, by coupling the pulse source to the draw roller by way of a gear change transmission. A more favorable embodiment for this purpose is obtained when an adjustable pulse divider is used to connect the pulse source to the control element. This has the advantage that the duration of the programme can be adapted to the feed rate of the yarn in a simple manner. As used herein the expression pulse divider is meant to refer to an apparatus which emits one or more output pulses for every n successive pulses that are fed to its input.

Another aspect of the present invention is directed to a method for twisting a yarn by the use of a twisting device comprising at least one variable speed winding spindle of the type heretofore described and a twisting member rotating around the spindle which is characterized in that the speed of the winding spindle is always given such a value that the speed n (v) of the twisting member satisfies the equation:

where:

n (v)=the desired speed of the twisting member correrespond-to the value v of the progress variable representing the growth of the package; n (v )=the desired speed of the twisting member at the beginning of the doff, the progress variable v having the initial value v and f(v):a programmed function value dependent on the progress variable v, defined by the object to be attained by means of the course of the values of the speed This method is based on the ascertainment that in order to obtain a particular course for the balloon tension during the dolf, the function:

(which is directed to obtaining this course), is not dependent on the twist and the feed rate V(,,). In this method, the speed of the winding spindle, itself, is not programmed as a function of the variable v, as in the known process, but rather the function value (v) is grammed. The function f(v) may, for instance, be chosen to obtain a constant balloon tension. By constant balloon tension is to be understood that during the dotf the balloon tension always has the same value at a particular position of the ring rail or spindle-carrying bar. The course of the balloon tension also may be directed to counteracting contractions in the yarn which may occur after unwinding the yarn packages. In this proposed method, it is not necessary, as is the case in the known process, to use a different programme carrier for a different value of the twist. Since, as explained above, in the case of a programmed spindle speed, the twist T will vary, it is more correct to speak of the choice of a different twist range than of the choice of a different twist. This twist range is bounded by the lowest and the highest value of the twist T. However, the twist range is sufficiently characterized by the magnitude of the twist level at the beginning of the dolf, which twist level is defined by the equation:

Hereinafter reference will therefore be made to a different initial twist instead of to a different twist range.

A first variant of the method for twisting yarn is characterized in that the speed of the twisting member is measured, and the measured speed It, is compared with the speed n (v) corresponding to the value v of the progress variable, and when a difference is registered between the measured speed n, and the speed n (v), the speed of the winding spindle is given such a value that said difference is reduced.

Another variant is characterized in that a programmed quantity is formed which is proportional to the value 11,01) which follows from the relation:

n (v)/n (v =f(v), and a quantity is formed which is proportion to the value V(v)/1rd(v) where:

V(v)=the rate at which the yarn is fed to the twisting apparatus at the value v of the progress variable representing the growth of the package; and

d(v)=the diameter of the yarn package corresponding to the value v of the progress variable;

and the quantities are proportional to said values in accordance with the same factor, and the sum of the two quantities is formed, and the sum obtained represents the desired value of the speed of the winding spindle corresponding to the value v of the progress variable.

A third variant of this twisting method is characterized in that the speed n of the winding spindle is measured, and a first control quantity is formed which is proportional to the value n (v), which follows from the relation n (v)/n (v :f(v), and a third control quantity is formed which is proportional to the value V(v)/1rd(v) where:

V(v):the rate at which the yarn is fed to the twisting device at the value v of the progress variable; and

package diameter corresponding to the progress variable;

d(v) =the yarn value v of the and said quantities are proportional to said values in accordance with the same factor, and the difference is formed of the control quantity proportional to the speed n and one of the two control quantities proportional to 11,01) and V(v)/1rd(v), respectively, and said difference is compared with the other of the two control quantities proportional to V(v)/1rd(v) and 12,0 respectively, and in the case of a deviation between said difference and the control quantity compared therewith the speed of the winding spindle is given such a value that said deviation is reduced.

With all these variants it is ensured that during the doff the speed of the twisting member follows a prescribed course. This is of importance if the balloon tension is to follow a predetermined course. For, in the case of ring twisting machines the balloon tension (for a given type of yarn and with given values of the initial diameter of the yarn package, the traveller weight, and the balloon height) is only influenced by the traveller speed n, and the prevailing package diameter d. By basing the course of the speed n of the winding spindle not directly on the balloon tension, but on the quantities n, and a, it is not necessary to measure the balloon tension. Such a measurement is not desirable in that it entails additional contact with the usually delicate yarn.

For carrying out the above-described method for twisting yarn, this invention also is concerned with an apparatus for the twisting of the yarn, more particularly a draw-twisting apparatus which comprises a twisting device having at least one Winding spindle and a twisting member rotating around the winding spindle on Which the twisted yarn is wound into a yarn package, and a programming unit which, during the winding process, serves to continuously impart a desired value to the speed of the winding spindle, said value being a function of a progress variable v, preferably the package diameter, which represents the growth of the package.

This apparatus is further characterized as having a programming unit programmed to include a function value f(v) dependent on the progress variable v, and having a first means for producing a control quantity proportional to the speed n (v a second means for forming a control quantity proportional to the speed n (v) of the twisting member, which speed satisfies the equation:

t( t( b)=f( where:

n (v)-=the desired speed of the twisting member, corresponding to the value v of the progress variable,

n (v )=the desired speed of the twisting member at the beginning of the doll, the progress variable v having the initial value v and f(v) =a function value dependent on the progress variable v, defined by the object to be attained by the course of the value n,(v),

providing the rotary speed of the that the speed of the and a third means for winding spindle with such a value twisting member is equal to n (v).

The quantities used could be obtained with the aid of analogue elements such as analogue multipliers, dividers and generators.

For greater simplicity, however, an embodiment of the apparatus is preferred, in which the first means comprise a first pulse source for the supply of pulses, the repetition frequency of which is proportional to the speed n (v and the second means includes a first pulse divider to which these pulses are applied. The frequency division of the pulse divider is set to a value corresponding to the function value f(v) under the control of the programming unit, so that the repetition frequency of the pulses emitted by the pulse divider is proportional to n,(v) following from the equation:

An apparatus of this type, comprising a variable driving motor for driving the winding spindle, may be constructed in different ways, depending on the type of process it is to carry out. A preferred embodiment of the apparatus for carrying out the first variant is characterized in that the driving motor is included in an automatic control loop, the controlled quantity of which forms the speed n (v) of the twisting member. The control loop also includes a digital automatic controller and a detecting element in the form of a pulse source which is connected to a first input of a comprising element of the controller and which emits pulses having a repetition frequency proportional to the actual value n of the rotary speed of the twisting member. The pulse train emitted by the first pulse divider is applied to a second input of said comparing element. When a difference is established by the comparing element between the frequencies of the pulse trains applied thereto, the control loop varies the speed of the driving motor so that said difference is reduced.

It will also be understood instead of a variable driving motor, a driving combination consisting of an electric motor or the like, coupled to a speed variator i.e. a gearing system with variable transmission ratio may also be used.

For carrying out the second variant of the method for twisting a yarn it is preferred to use an apparatus which is characterized as having a second pulse source which emits pulses having a repetition frequency proportional to the rate V(v) at which the yarn is fed to the twisting device, a second pulse divider to which the pulses are applied, the frequency division of the pulse divider, under the control of the programming unit, is set to a value corresponding to the value 1rd(v), so that the repetition frequency of its emitted pulses is proportional to where d( v) =the diameter of the yarn package corresponding to the value of v of the progress variable; and a summing device to which the pulse trains emitted by the heretofore mentioned first pulse divider and by the second pulse divider are applied and which emits pulses having a repetition frequency proportional to the sum:

The speed of the driving motor, under the control of the last-mentioned train is thereby set to a value at which the speed n of the winding spindle is equal to said sum.

For said last-mentioned apparatus it is preferred that the driving motor is included in an automatic control loop, the controlled quantity of which forms the speed of the winding spindle. The control loop also includes a digital automatic controller and a detecting element in the form of a pulse source connected to a first input of a comparing element of said controller, which emits pulses having a repetition frequency proportional to the actual value n of the speed of the winding spindle. The pulse train from the summing device is applied to a second input of said comparing element, and in the case, a difference is registered by the comparing element between the repetition frequencies of the pulses applied thereto, the control loop varies the speed of the driving motor so that the difference is reduced.

When the apparatus having a variable driving motor is used to carry out the third variant of the yarn twisting method, a particularly advantageous embodiment is further characterized as having a pulse source which emits pulses with a repetition frequency proportional to the actual value 12' of the speed of the winding spindle, a second pulse source (such as heretofore used above) which emits pulses with a repetition frequency proportional to the rate V(v) at which the yarn is fed to the twisting apparawhere d(v)=the yarn package diameter corresponding to the value v of the progress variable; and a subtraction device to which the pulses having the repetition frequency proportional to the actual value n of the speed of the winding spindle and one of the two series of pulses having the repetition frequency proportional to n (v) and V(v)/1rd(v), respectively, are applied. In this embodiment, the subtraction device emits pulses, the repetition frequency of which is proportional to the difference of the repetition frequencies of the pulses applied thereto, and the driving motor is included in an automatic control loop, the controlled quantity of which is formed by and n (v), respectively. The control loop also includes a digital automatic controller with a comparing element that makes a frequency comparison of the series of pulses from the substraction device with the series of pulses, the repetition frequency of which is proportional to V(V)/7I'd(V) and n (v) respectively. When a frequency difference occurs between the compared pulse trains, the control loop varies the speed of the driving motor so that the difference is reduced.

It will be appreciated that the second pulse source used to produce a control quantity proportional to the feed rate of the yarn in the apparatus for twisting yarn may be similar to the pulse source similarly used in the heretofore described winding apparatus.

Also, when an apparatus for drawtwisting of a yarn is to be used for carrying out the second or third variant of the twisting method, then it is recommended to couple the second pulse source to one of the rollers of the drawtwisting apparatus and preferably to the draw roller, as heretofore discussed in the description of the winding apparatus.

A particularly advantageous embodiment of the twisting apparatus has means for forming a control quantity proportional to the feed rate of the yarn supplied to the twisting apparatus and a control element through which the programming unit is controlled by said quantity, so that the programme is executed in a period of time proportional to said feed rate.

The programs used for the twisting apparatus will as a rule also be stored in a programme carrier, such as a magnetic tape, a magnetic disk, a punched tape, a programme storing card or the like.

It is also possible for the programmed quantity to be represented, for instance, by an electric voltage which is varied by contacts being opened and closed in a particular configuration controlled by a memory. In all these cases the control element controls the speed at which the programme is executed. When a programme carrier is used which, during the execution of the programme, carries out a movement relative to a sensing device, then the control element may be used to effect this movement.

The above-mentioned means for forming the control quantity preferably comprise a pulse source for applying to the control element pulses the repetition frequency of which forms the quantity proportional to the feed rate of the yarn.

Furthermore, it will be understood that where applicable the programming unit, the programme carrier, the control element and the second pulse source of the twisting apparatus may be arranged to cooperate in a manner similar to that heretofore discussed in detail with reference to like elements of the winding apparatus.

For example, when the twisting apparatus is to be used Cir for drawtwisting, then it is preferred to couple the pulse source which generates frequencies proportional to the yarn feed rate to the draw roller, since in this case if the draw rate is left unchanged and the draw ratio is changed, the duration of the programme will remain the same. But if the execution of the programme should be controlled by a pulse source coupled to the feed roller, then the changing of the draw ratio would be accompanied by a changing of the duration of the programme.

When the above-discussed twisting apparatus are used for the purpose of drawtwisting it is preferred that the draw roller is coupled to a drive the rotary speed of which is variable independent of the winding spindle.

In this way it is possible for the draw rate to be adjusted in a simple manner without the necessity of exchanging gears. This is of particular advantage in the case of a drawtwisting apparatus according to the invention since it is desirable that when the drawtwisting machines are strung up, a reduced draw rate is applied. By stringing up is meant the combination of operations by which, prior to the winding and twisting, the yarn is laid in its appropriate path between the yarn supply package and the twisting apparatus. The low draw rate then used often results in a low balloon tension, which may lead to filament wraps on the draw rollers.

However, with the method and apparatus (used for winding or for winding and twisting of yarn) the speed of the winding spindle automatically adapts itself to the applied draw rate. This adaptation is such that the traveller speed in the twisting apparatus always assumes the value at which the desired balloon tension is obtained.

It will be recognized that the draw roller may be coupled to the driving motor of the winding spindle through a gearing with infinitely variable transmission ratio. However, it is preferred that the drive of the draw roller comprises a driving motor with variable speed. In this way there is no need for a mechanical transmission system between the driving motor of the winding spindles and the draw rollers.

It is preferred that the driving motor of the draw roller is included in an automatic control loop the controlled quantity of which corresponds to the speed of this driving motor. The control loop also includes an automatic controller and a detecting element for the speed of the driving motor, which element is connected to a first input of said controller.

Further it is recommended that a digital automatic controller be provided and that the detecting element is formed by the second pulse source.

It is further advantageous to connect a second input of the digital automatic controller to the first pulse source, which applies pulses to said controller the repetition frequency of which represents the desired value of the speed of the driving motor.

A very simple adjustment of the speed of the driving motor for the draw roller is obtained if to at least one of said two inputs of the automatic controller there is connected a pulse divider with adjustable frequency division.

For the first pulse source used in the twisting apparatus use may be made of an apparatus consisting of a drive having an output shaft with variable rotary speed and a pulse detecting unit in the form of a pulse source coupled thereto. The speed of the output shaft is set proportional to the traveller speed n (v adapted to the desired initial twist.

However, preference is given to an apparatus having a first pulse source that is formed by an electronic pulse generator with a variable frequency.

When the above-described twisting apparatus are to be used for carrying out drawtwisting processes, a further important improvement is obtained when the feed roller is coupled to a drive whose rotary speed is variable independent of the speed of the winding spindle.

In accordance with this invention since the balloon 13 tension level is maintained at a reasonable value, the life of the traveller is prolonged. For a drawtwisting machine with programmed spindle speed, the life of the traveller may extend over a period of time in which the yarn of more than one supply package may be drawn, twisted and wound to pirns.

In order to avoid repeated stringing-up of the apparatus with each fresh supply package, the trailing yarn ends of the practically unwound supply packages may be tied to the leading ends of fresh supply packages. It is desirable then that the draw ratio is temporarilydecreased in order to avoid breakage at the knot in the drawing zone. The reduced draw ratio may be obtained by reducing the rotary speed of the feed rollers. The feed roller may, for instance, be coupled to the driving motor of the winding spindle through a drive with infinitely variable transmission ratio.

Alternatively, when the speed of the draw roller is independently variable, then the feed roller may be coupled to the draw roller through a geared transmission. However, it is preferred to use an apparatus in which the feed roller is coupled to a drive, having a speed which is variable independent of the drive of the draw roller. Such a drive for the feed roller may, for instance, be obtained by inter-coupling the draw rollers and the feed rollers by means of a speed variator.

It is preferred, however, that the drive of the feed roller comprises a driving motor with variable speed.

Preferably, the driving motor of the feed roller used in the twisting apparatus is included in an automatic control loop the controlled quantity of which corresponds to the speed of the driving motor. The control loop also includes an automatic controller and a detecting element for the speed of the driving motor which detecting element is connected to a first input of said controller.

Furthermore, as in the other heretofore described control loops, it is preferred that a digital automatic controller be provided and that the detecting element of the loop is formed by a pulse source coupled to the driving motor of the feed roller, so that the source supplies pulses having a repetition frequency which is proportional to the speed of the driving motor.

Further, it is of advantage when a second input of the digital automatic controller is connected to the second pulse source, which applies pulses to said controller at a repetition frequency which represents the desired value of the speed of the driving motor for the feed roller.

The speed of the driving motor for the draw roller may be set in a very simple manner, if to at least one of said two inputs of the automatic controller for the driving motor of the feed roller there is connected a pulse divider with adjustable frequency division.

It will be understood that this invention also is concerned with the yarn treated by any one of the proposed methods of winding and/ or twisting.

The invention will be further described with reference to the accompanying drawings in which:

FIGURE 1 schematically shows one embodiment of the apparatus of the invention; and

FIGURE 2 schematically shows another embodiment of the invention.

FIGURE 1 shows a part of an apparatus on which a yarn is subjected to a drawing treatment and subsequently wound into a package. An apparatus of this type may be a spin-drawing machine, a draw-winding machine or a drawtwisting machine. With the first-mentioned apparatus the yarn is, in a continuous process, successively spun, drawn and wound into a package. With the draw-winding and drawtwisting machines, however, the yarn to be treated is supplied from a yarn package, subsequently drawn and finally wound again into another package. With the drawtwisting machine the drawn yarn is also twisted. It will hereinafter be understood that FIGURE 1 relates to one of the drawtwisting positions of a drawtwisting apparatus. (It will be understood that this invention is particularly adapted to be used for such yarn treating machines.) Since the construction of a drawtwisting machine is known in itself, FIGURE 1 shows only those elements that must be illustrated for a proper understanding of the invention.

The reference numeral 1 designates a draw roller, which .forms part of a drawing apparatus (not shown). A spindle motor 2 drives a winding spindle which is diagrammatically shown by dash lines at one of the drawtwisting positions. Coupled to the draw roller 1 is a pulse source 3, which emits pulses that have a repetition frequency that is proportional to the rotary speed of the draw roller. These pulses are applied to two pulse dividers 4 and 5, which emit one or more output pulses for a particular number of pulses fed to their input. The repetition frequency of the pulses emitted by these pulse dividers is therefore only part of that of the pulses emitted by the pulse source 3. The frequency division of the pulse dividers 4 and 5 is adjustable. The pulse divider 4, of which the frequency division can be adjusted by hand, applies its pulses to a stepping motor 6, whose shaft is coupled to a programming unit 7. The programming unit 7 so sets the frequency division of the pulse divider 5 during a doif that the repetition frequency of its emitted pulses is varied in accordance with a desired course. In the pulse divider 5 the repetition frequency of the pulses that represent the yarn feed rate is multipled by a programmed quantity that corresponds to the reciprocal value of the frequency division.

The programming unit 7 comprises a programme carrier in the form of a programme storing card, which is known in itself, and which is provided with ridges that cooperate with microswitches. The programme storing card is advanced stepwise by the stepping motor 6. In a doif the programme storing card is displaced a given number of steps. Since the setting of the pulse divider 4 is adjustable, the step frequency may at all times be adapted in a simple manner to the duration of the deli. If the yarn package is to have a weight G, then the duration of the doff t follows from the equation:

where V is the draw rate and T the linear density of the yarn in deniers. The pulse source 3 takes into account the draw rate V, so that in setting the pulse divider 4 the variation of G/T is the only factor to be reckoned with.

It will be clear that in this way the duration of the doff is not a fixed quantity, but is dependent on the time required to have the programme-storing card carry out a complete movement. This time is governed by the repetition frequency of the pulses emitted by the pulse source 3. Before a doff is completed, the draw roller 1 must therefore have made a fixed number of revolutions. In any doif carried out using a given programme storing card, a given draw rate and a given setting of the pulse divider 4, the same length of yarn is wound into a package. Coupled to the spindle motor 2 is a detecting element in the form of a second pulse source 8, which emits pulses having a repetition frequency proportional to the rotary speed of the spindle motor, and consequently to that of the winding spindle. These pulses and those emitted by the pulse divider 5 are applied to a comparator or comparing device 9 forming part of an automatic controller 10. The comparator compares the repetition frequencies of the two series of pulses. Provided between the comparator 9 and the spindle motor 2 is a transducer consisting of a controlling unit 38 and a correction element 39. When the comparator registers a difference between the repetition frequencies of the pulses applied thereto, it adjusts, by way of the transducer elements 38 and 39, the rotary speed of the spindle motor 2 in such a sense and for such a time that the two compared pulse repetition frequencies again become equal. Consequently, during the doff the rotary speed of the spindle motor 2, and hence that of the wind- 15 ing spindle, follows the course prescribed with the aid of the programming unit 7.

The pulses emitted by the pulse divider 4 are applied not only to the stepping motor 6, but also to two pulse dividers 11 and 12. Also the frequency division of these pulse dividers is set by the programming unit 7. The pulses emitted by the pulse dividers 11 and 12 are applied to stepping motors 13 and 14, respectively, which may communicate a rotary movement to screw spindles 15 and 16, respectively. Provided on the screw spindles are slides 17 and 18 to which switches 19 and 20, respectively, are attached. The positions of the slides define the upper and lower reversing points of the traverse motion carried out by the ring rail or spindle-carrying bar during the formation of the yarn package. To this end, there is provided a rod 21, which carries a projection 22, which co-operates with the switches 19 and 20. The rod 21 makes a movement which corresponds to the traverse movement or motion of the ring rail. When the ring rail or spindlecarrying bar moves in upward direction and the projection strikes the operating member of the switch 19, the direction of the traverse motion is reversed. The next reversal of the traverse motion takes place when the projection 22 strikes the operating member of the switch 20. The upper and lower reversing points may be set independent of each other. In this regard, the programming unit 7 has two programmes in accordance with which the frequency division of the pulse dividers 11 and 12 is set. When the package is to have a symmetrical build-up, it is sufficient to use one programme for the setting of the pulse dividers 11 and 12. A control device of this type for the traverse motion in spinning machines and winding machines, more particularly in drawtwisting machines is described in the French Patent No. 1,362,200.

The course that is the variation of the rotary speed of the winding spindle may be chosen in accordance with different requirements. For instance, the course may be so chosen that during the doff the ballon tension or the traveler speed is constant. Or it may be so chosen that during the doff the balloon tension or some different quantity passes through predetermined values, for instance, for the purpose of influencing the yarn properties. More particularly, such a course of the balloon may be chosen as to counteract differences in the yarn contraction, which may occur after unwinding from drawtwisting pirns. Or the course may be so chosen that the occurrence of mirror patterns in the yarn package is prevented. Such mirror patterns may be formed in the case of drawtwisting machines with inclined traveller rings when as heretofore described, the ratio of the difference between spindle speed and traveller speed to the traveller speed itself is an integer or if the reciprocal value of this ratio is an integer.

When in drawtwisting, the balloon tension is to have a particular course, the appropriate programme can be determined as follows. Yarn of the type and linear density to be used is wound, on a yarn tube of a given diameter and at the desired twist level, to a yarn package of the desired shape and weight. During the doff the rotary speed of the winding spindle at which the ballon tension has the desired value is determined as a function of a variable which represents the growth of the package, such as the time, or preferably the diameter d of the yarn package. Let the course thus obtained for the spindle speed as a function of the package diameter d be represented by n (d). If, furthermore, the draw rate used with this spindle speed is V then a factor proportional to the quotient n (d)/V is programmed. This programmed quantity, as a function of the package diameter d, passes through values each of which corresponds to the quotient n (d) V relating to a particular value for d. For instance, for the package diameter d said quantity is proportional to the quotient n (d V It will be clear therefore that the repetition frequency of the pulses emitted by the pulse divider 5 is now proportional to V0 where V is the draw rate being used. The winding spindle is then automatically driven by the spindle motor 2 at a rotary speed that is V/V times higher than if the draw rate used should be V in this way the course of the balloon tension has been made independent of the magnitude of the draw rate. This is based on the fact, that in order for a given course for the balloon tension to be obtained during the doff, irrespective of the magnitude of the rotary speed V, it is only necessary to consider the relation:

t( t,( b)

where: n (d)=the speed of the traveller corresponding to the value d of the package diameter, and n (d =the speed of the traveller at the beginning of the doff, the package diameter having the value d When, as in the case of the proposed winding method, a variation in the draw rate V results in a proportional variation in the rotary speed of the winding spindle, then the values in will also undergo a proportional change. Consequently, the relation:

raw awn remains unchanged. Although there is no change in the course in the programmed variation, of the balloon tension, there does take place a change in the magnitude of the balloon tension.

Thus, a variation in the draw rate during the doff will not result in a change in the constancy but will vary the magnitude of the balloon tension.

This change may, however, be compensated for by using a traveller having a different weight.

Although the apparatus shown in FIGURE 1 is particularly suitable for drawtwisting machines, its application is not limited thereto. The invention may also be used for the spin-drawing and draw-winding processes when the yarn, as in the above-described examples, is wound in to a spindle-driven package. By the term spindle-driven it is meant that the yarn package is driven by the winding spindle on which the package is placed, and not by a rotary member that is in contact with the circumferential surface of the package. For instance, in the spin-drawing process the rotary speed of the winding spindle must, during the winding operation, be so varied that the peripheral speed of the yarn package is equal to the draw rate of the yarn. If there is a difference between these two speeds, the yarn will be subject to undesirable variations in the tension, which in turn give rise to variations in linear density and to other defects.

The rotary speed of the winding spindle must therefore be varied in dependence on a variable representing the growth the package, such as the time, or preferably the package diameter, and must be given such a course that the peripheral speed remains equal to the yarn feed rate. If this course is programmed, as in the known method, winding by the known method has the afore-mentioned disadvantage that such a programme is only suitable to be used for one particular yarn feed rate. If the yarn is supplied at a deviating rate, use must be made of a different programme, which is adapted to the deviating feed rate. Also in this case, and in general in those cases where it is desired to wind yarn into a spindle-driven package at various yarn feed rates, the present invention overcomes these difficulties.

The quantity to be programmed in accordance with one aspect of the invention, must, as a function of a variable representing the growth of the package, pass through values each of which is proportional to the rotary speed of the winding spindle which is, at a particular value of said variable, and at a given feed rate V require for the peripheral speed to be equal to the yarn feed rate. In this way not only is the programme made independent of the yarn feed rate, but the provisions according to the invention also have the advantage that if the yarn feed rate is subject to variations during the winding operation, the rotary speed of the winding spindle is automatically adapted to these variations, such variation could, for instance, be applied for the purpose of influencing the yarn properties.

The embodiment of the invention illustrated in FIG- URE 2 is used as a drawtwisting machine in which the balloon tension in the yarn is to be kept constant through the doff.

In the drawing the reference numeral 41 refers to a feed roller which is driven through a shaft 42 by a driving motor 43. On the shaft 42 there are a plurality of feed rollers, each of which belongs to a drawtwisting position. The feed roller 41 transports the yarn to be treated to a drawing zone which is located between the feed roller and a draw roller 44. The draw roller is driven through a shaft 45 and a partly visible conical gear transmission 54 by a driving motor 46. The draw ratio in the drawing zone is governed by the ratio of the peripheral speeds of the rollers 41 and 44.

The yarn leaves the drawing zone at a given rate, the drawing rate, and is fed to a twisting apparatus known in itself and provided with a winding spindle on which the yarn is wound to a yarn package. The winding spindle which is shown together with a traveller and the yarn in dashed lines, just as the winding spindles of the other drawtwisting positions of the drawtwisting machine, is driven by a spindle motor 47. Before being wound the yarn passes a twisting member in .the form of the traveller. During the dofi the traveller rotates relative to the winding spindle so that while the yarn is wound some amount of twist is imparted to it. The speeds of the motors 43, 46, and 47'may be controlled in the following manner. On the shaft 42 of the driving motor 43 there is a pulse source 48 which emits electric pulses having a repetition frequency that is proportional to the speed of the feed roller 41.

' These pulses are applied to a control unit 50 via a line 49. The control unit 50 serves to control the speed of the driving motor 43, with which it forms an automatic control loop. To the control unit 50 a train of pulses emitted by a pulse divider 51 is also applied. Of a particular number of pulses applied to its input the pulse divider 51 applies one or more pulses to the control unit 50. The input pulses of the pulse divider are supplied through the line 52 and are emitted by a pulse source 53. This source is coupled to the driving motor 46 of the draw roller 44. The pulse source 53 emits pulses having a repetition frequency that is proportional to the speed of the draw roller and consequently to the speed V at which the yarn is fed to the twisting apparatus. These pulses are applied to two pulse dividers 55 and 56 each of which emits one output pulse to a given number of pulses applied to their inputs. The repetition frequency of the pulses emitted by these pulse dividers is therefore only part of that of the pulses emitted by the pulse source 53. The frequency division of the pulse dividers 55 and 56 is adjustable. The pulse divider 55, the frequency division of which can be adjusted by hand, applies its pulses to a stepping motor 57 whose shaft is coupled to a programming unit 58.

The programming unit so sets the frequency division of the pulse divider 56 that the repetition frequency of its outgoing pulses is proportional to V/1rd, where d represents the prevailing yarn packagediameter. Since, for a particular build-up or growth of the yarn package, its diameter d, as a function of the length of the wound yarn, may be determined beforehand, the course of the diameter during the dolf may be programmed. The programming unit 58 comprises a programme carrier in the form of a programme storing card (not shown), which is provided with ridges which co-operate with microswitches in the programming unit. The programme storing card is advanced stepwise by the Stepping motor 57. In a doff the programme storing card is displaced a given number of steps. Since the setting of the pulse divider 55 is adjustable, the step frequency may at all times be adapted in a simple manner to the duration of the dofi. As heretofore pointed out, if the yarn package is to have a weight G, then the corresponding duration t of the doff follows from t =9000/V.T Where V is the draw rate and T, the linear density of the yarn in deniers. The pulse source 53 takes into account the draw rate V, so that in setting the pulse divider 55, variation of G/T is the only factor that must be considered.

It will be clear that in this way the duration of the doff is not a fixed quantity, but is dependent on the time required to have the programme storing card carry out a complete movement. This time is governed by the repetition frequency of the pulses emitted by the pulse source 53. Before a doff is completed, the draw roller 44 must therefore have made a fixed number of revolutions. In any dolf carried out using a given programme storing card, a given draw rate, and a given setting of the pulse divider 55, the same length of yarn is wound into a package.

An electronic pulse generator 70' generates a train of pulses 'which are applied to a pulse divider 60. The pulse generator 70 comprises a generator 59 'which produces pulses of a constant stabilized frequency and a pulse divider 69 with adjustable frequency division. The pulse divider 69 serves to vary the frequency of the pulse generator 70. The repetition frequency of the pulses applied to the pulse divider '60 is proportional to the traveller speed n (d at the beginning of the doif and may be set to a value corresponding to the desired value of the initial twist. Also the pulse divider 60', as far as its frequency division is concerned, is under the control of the programming unit 58. To this end an additional control programme is included in the programme storing card of the programming unit 5 8. This additional programme so sets the pulse divider 60 that the reptition frequency of its emitted pulses is proportional to the traveller speed n (d) desired at a given moment. Said speed satisfies the relation:

t t( b)=f( where: n,, (d) =the desired speed of the traveller when the package diameter has the value d; and n (d =the desired speed of the traveller at the initial diameter d of the yarn package. Hence, the package diameter d serves as a progress variable which represents the progress of growth of the yarn package.

As mentioned before, the function f(d) is independent of the twist and the feed rate V(d). The function f(d) is still influenced by the linear density, the type of yarn, the diameter of the yarn tube and traveller ring. The influence of the linear density is such that the range of the required linear density may be divided into sections within each of which use may be made of the same programme, provided that the type of yarn and the diameter of the yarn tube and traveller ring remain the same.

The function f(d) may be determined by experiment. For example, it can be determined during the doff which traveller speed n (d) is required at a given package diameter d to achieve the object desired. If, as in the case under consideration, a constant balloon tension is desired, then the speed of the winding spindle is changed until the required balloon tension is obtained. Then the corresponding traveller speed may, for instance, be determined stroboscopically. It is, of course, also possible to determine the desired traveller speed n (d) in accordance with the equation:

ol) m d)- d) where n (d) is the measured speed of the winding spindle at which the balloon tension assumes the desired value and d the corresponding yarn package diameter.

the function f (d)=n (d)/n (d pertaining to the tube diameter d follows from the previously determined function f(d)=n (d)/n (d If for each value of d the pertaining function value (d) is multiplied by the factor 11 ,(d) /n (d l/f(a' this factor is the value of l/f(d) for d=d Such an adaptation of the relation n (d)/n (d to the applied yarn tube diameter may be effected with the aid of a computer which co-operates with a number of (draw)-twisting machines to work out the programmes therefor. This co-operation is of importance if yarn packages of different shapes, and yarns of different thicknesses must be wound. If in that case the programme is divided into a number of steps, the computer may, on a basis of the desired shape of the package, the total length of yarn to be wound, and the yarn thickness, calculate to what package each of the steps of the programme corresponds.

As far as the influence of the diameters of the traveller rings is concerned, it has been found that for traveller rings of inches or 5% inches, one programme is sufficient.

The pulse trains emitted by the pulse dividers 56 and 60 are applied to a summing device 61 which derives therefrom those pulses having a repetition frequency which is proportional to the sum of the repetition frequencies of the pulses applied thereto. Since the repetition frequencies of these pulses are proportional to the terms V(d) /1rd and n (d) in the same ratio, the sum frequency is proportional to This sum frequency now represents the desired value of the speed n,(d) of the winding spindle at the moment the yarn package diameter has the value d. In order that the speed of the winding spindle also may always assume the desired value, the spindle motor 47, as well as the driving motors 43 and 46, are included in an automatic control loop.

The main elements of this control loop are a digital automatic controller 62, a correcting element 63 and a detecting element in the form of a pulse source 64. The pulse source 64 is coupled to the shaft of the spindle motor 47 and emits pulses with a repetition frequency of that which is proportional to the speed of the spindle motor 47, and consequently, to the speed 11 of the winding spindle.

These last-mentioned pulses and those from the summing device 61 are applied to the comparing element 65 in the automatic controller -62. The comparing element compares the repetition frequencies of the two series of pulses.

The automatic controller 62 further comprises a controlling element 66 which is connected between the comparing element 65 and the correcting element 63. When the comparing element registers a difference between the repetition frequencies of the pulses applied thereto, it adjusts, through the controlling element 66 and the correcting element 63, the rotary speed of the spindle motor 47 in such a sense and for such a time that the two compared repetition frequencies become equal again. Consequently, during the dQff the rotary speed 11, of the winding 20 Spindle follows the coarse prescribed by the programming unit 58.

The automatic control loop for the driving motor 43 is built the same way as that for the spindle motor 47, which is heretofore further described in the description of the winding apparatus of this invention. For instance, the control unit 50 comprises an automatic controller and a correcting element corresponding to the parts 62 and 63. respectively. A similar control unit referred to by the reference numeral 67 is provided for the control of the speed of the driving motor 46. To this control unit 67 two pulse trains are applied. One of these pulse trains is from the generator 49, the other from the pulse source 43. The latter pulse train first passes through a pulse divider 68 before being applied to an input of the control. unit 67. The frequency division of the pulse divider is adjustable by hand.

With the aid of the described control loops for the driving motors 43 and 46 it is possible to vary the draw rate and the draw ratio separately or simultaneously so that with regard to both the draw rate and the draw ratio widely varying requirements may be satisfied. A change of the frequency division of only the pulse divider 68, for instance, results in the driving motor 46 driving the draw roller 44 at a correspondingly varied speed. Since at the same time the speed of the driving motor 43 varies proportionally, only the draw rate is changed. If, however, the ratio is to be changed and the same draw rate is to be maintained such a change may be effected by only varying the frequency division of the pulse divider 51. Finally, if both the draw rate and the draw ratio are to be changed, then both the setting of the pulse divider 51 and that of the pulse divider 68 must be modified.

The initial twist T may, if desired, be re-set by correspondingly adjusting the frequency of the pulse generator 70. The speed n of the winding spindle now automatically adapts itself to the newly set twist without it being necessary to use a new programme. If the programme is directed to obtaining a particular course of the balloon tension and this course must also be maintained for the changed initial twist, then it is only necessary to replace the travellers. If, for instance, the initial twist has been increased, then it will be necessary to use travellers having a lower weight, since the traveller speed, under otherwise equal conditions will now have its course at a higher level. If, on the other hand, a different draw rate is to be used, and the resulting change in the initial twist is only relatively small and, therefore, admissible, then the travellers need not be replaced.

What is claimed is:

1. A method for winding a yarn into a yarn package which comprises feeding the yarn to a winding apparatus, said winding apparatus having a variable speed spindle, winding the yarn onto said spindle to form a yarn package, varying the rotary speed of the spindle on which the package is formed in accordance with a preselected programme as a function of a process variable v representing the growth of the package, producing a first control quantity that is proportional to the feed rate of the yarn to said winding apparatus, forming a programmed quantity in accordance with said preselected programme that is a function of the process variable v and that passes through values each of which is proportional to the rotary speed n (v) of the spindle required at the corresponding value of the process variable v and at a particular yarn feed rate V combining said first control quantity and said programmed quantity to form a product control quantity V. n (v)/V that is proportional to the rotary speed of the spindle, producing a second control quantity that is proportional to the rotary speed of the spindle and comparing the product control quantity with the second control quantity and thereafter controlling the rotary speed of the spindle and the formation of the yarn package so that the product control and the second control quantities are equal, whereby the preselected programme is made in,

21 dependent of the feed rate of the paratus to allow changing of the ing said programme.

2. The method of claim 1 in whichthe programmed quantity is proportional to the quotient n,,(v)/V 3. The method of claim 1 in which the yarn is first drawn in a continuous process on a drawing apparatus provided with at least one feed roller and one draw roller, prior to being wound by the winding apparatus, the control quantity that is proportional to the feed rate of the yarn being derived from one of the rollers of the drawing apparatus.

4. The method of claim 3 in which the control quantity that is proportional to the feed rate of the yarn is derived from the draw roller.

5. The method of claim 1 in which the control quantity which is proportional to the rate at which the yarn is fed to the winding apparatus, controls the execution of the programme, whereby the programme is executed in a period of time which is proportional to the feed rate of the yarn.

6. A method for twisting and winding a yarn into a package on a twisting device comprising a twisting member rotating around a variable speed spindle, which comprises feeding a yarn to said spindle via said twisting member, imparting twist to said yarn and simultaneously winding'the yarn into a package on said Spindle, imparting a value to the speed of the spindle in accordance with a preselected programme as a function of a process variable v representing the growth of the package, and controlling the value given to the speed of the spindle so that the speed n (v) of the twisting member satisfies the yarn to said winding apfeed rate without changequation:

where: n (v)=the desired speed of the twisting member corresponding to the value v of the progress varlable;

' f(v)= a programmed function value dependent on the I progress variable v, defined by the object to be attained by means of the course of the values of the speed n (v),

and so that the feed rate of the yarn to the twisting device can be varied without changing said preselected programme.

7. The method of claim 6 in which the speed n of the twisting member is measured, the measured speed n is compared with the speed n (v) corresponding to the value v of the progress variable, and in case a difference is registered between the measured speed 11, and the speed n (v), and the speed of the spindle is given such a value that said difference is reduced.

'8. The method of claim 6 in which a control quantity is formed which is proportional to the value n (v) which follows from the relation n (v)/n (v =f(v), a control quantity is formed which is proportional to the -value where: V(v)=the rate at which the yarn is fed to the twisting device at the value v of the progress variable;

and

d(v)=the diameter of the yarn package corresponding to the value v of the progress variable;

said control quantities being proportional to said values in accordance with the same factor, the sum of said quantities is formed, and the sum obtained represents the desired value of the speed of the winding spindle corresponding to the value v of the progress variable.

9. The method of claim 6 in which the speed n of the winding spindle is measured, a control quantity is formed which is proportional to said measured speed, a control quantity is formed which is proportional to the value n,( v), which follows from the relation:

n (v)/n (v =f(v), a control quantity is formed which is proportional to the value V( v)/1rd (v) where: V(v)=the rate at which the yarn is fed to the twisting device at the value v of the progress variable; and

d(v) =the yarn package diameter corresponding to the value v of the progress variable;

said quantities being proportional to said values in accordance with the same factor, a difference is formed of the control quantity which is proportional to the speed n and one of the two quantities which are proportional to n (v) and V(v)/1rd(v), respectively, said difference is compared with the other of the two quantities which is proportional to V(v)/1rd(v) and n,,( v), respectively, and in the case of a deviation between said difference and the quantity compared therewith, the speed of the winding spindle is given such a value that said deviation is reduced.

10. An apparatus for winding a yarn into a package which comprises at least one winding spindle on which the yarn is wound into a package means for feeding yarn to said winding spindle, a programming unit, said winding spindle driving the package, during the formation thereof, at a rotary speed which is varied, in accordance with a particular programme under the control of the programming unit, as a function of a process variable v which represents the growth of the package, said programming unit having a programme including a programmed quantity which, as a function of the variable v, passes through values each of which is proportional to the rotary speed n (v) of the winding spindle required at the corresponding value of the variable and at a particular feed rate V of the yarn fed to the winding apparatus, and control means operatively associated with said programming unit for forming a control quantity proportional to the yarn feed rate V to be applied for forming the product V.n (v)/V and for adapting the rotary speed of the winding spindle to the value of said product, whereby said yarn can be wound into a package at the feed rate to be applied without changing said preselected programme.

11. The apparatus of claim grammed quantity n (v)/V 12. The apparatus of claim 10 in which said control means comprise a pulse source which emits pulses having a repetition frequency proportional to the feed rate of the yarn, and a pulse divider to which said pulses are applied, the repetition frequency of the pulses emitted by the pulse divider being set under the control of the programming unit in accordance with the programmed quantity.

13. The apparatus of claim 10 in which said means for feeding yarn includes a drawing apparatus on which the yarn is drawn, said drawing apparatus having at least one feed roller and one draw roller said pulse source being formed by a pick-up element which is coupled to one of the rollers of the drawing apparatus.

14. The apparatus of claim 13 in which the pulse source is formed by a pick-up element coupled to the draw rollers. 4

15. The apparatus of claim 10 in which said control means includes means for forming the control quantity which is proportional to the rate at which the yarn is fed to the winding apparatus, a control element operatively associated with said programming unit, said control element being controlled by said control quantity, so that the programme in said programming unit is executed in a period of time that is proportional to the feed rate of the yarn.

16. The apparatus of claim 15 in which said means includes a pulse source for applying pulses to the control element, the repetition frequency of said pulses forming the control quantity that is proportional to the feed rate of the yarn.

17. The apparatus of claim 16 in which said means for feeding yarn includes a drawing apparatus provided with at least one draw roller, said pulse source being coupled to the draw roller.

10 in which said prois proportional to the quotient 18. The apparatus of claim 16 in which said control means further comprises an adjustable pulse divider by way of which the pulse source is connected to the control element.

19. The apparatus of claim in which said control element is an electric stepping motor.

20. An apparatus for the twisting and winding into a package of a yarn which comprises a twisting device having at least one winding spindle and a twisting member rotating around the winding spindle on which the twisted yarn is wound into a yarn package, means for feeding yarn to said spindle via said twisting member, a programming unit which serves to impart a desired value to the speed of the winding spindle, said value being a function of a progress variable v which represents the growth of the package, said programming unit including a function value f(v) dependent on the progress variable v in accordance with a preselected programme, and control means operatively associated with said programming unit for forming a control quantity proportional to the speed n (v for forming a control quantity proportional to the speed n (v) of the twisting member, which speed satisfies the equation:

"t( "t( b) =fi where:

n (v)=the desired speed of the twisting member, corresponding to the value v of the progress variable;

n (v =the desired speed of the twisting member at the beginning of the doff, the progress variable v having the initial value v and f(v):a function value dependent on the progress variable v, defined by the object to be attained by the course of the value n (v),

and for giving the rotary speed of the winding spindle a value such that the speed of the twisting member is equal to n (v) whereby the feed rate of the yarn to the twisting device can be varied without changing said preselected programme.

21. The apparatus of claim 20 in which said control means comprise a first pulse source for supplying pulses having a repetition frequency which is proportional to the speed n (v and a first pulse divider to which these pulses are applied, the frequency division of said pulse divider set to a value corresponding to the function value f(v) under the control of the programming unit, whereby the repetition frequency of the pulses emitted by the pulse divider is proportional to n (v), following from the equation:

n (v) /n (v =f(v) 22. The apparatus of claim 21 in which said control means further comprise a driving motor for driving the winding spindle, said driving motor being included in an automatic control loop, the controlled quantity of which forms the speed n (v) of the twisting member, the control loop also including a digital automatic controller and a detecting element in the form of a pulse source which is connected to a first input of a comparing element of said controller and which emits pulses having a repetition frequency which is proportional to the actual value n of the rotary speed of the twisting member; the pulse train emitted by the first pulse divider being applied to a second input of said comparing element and in case of a difference being established by the comparing element between the frequencies of the pulse trains applied thereto, said control loop varies the speed of the driving motor so that said difference is reduced.

23. The apparatus of claim 21 in which said control means includes a driving motor for driving the winding spindle, a second pulse source which emits pulse having a repetition frequency which is proportional to the rate V(v) at which the yarn is fed to the twisting apparatus, a second pulse divider to which these pulses are applied, the frequency division of the pulse divider under the control of the programming unit being set to a value corresponding to the value d(v), so that the repetition frequency of its emitted pulses is proportional to:

V(V)/1rd(v) where d(v)=the diameter of the yarn package corresponding to the value v of the progress variable;

d 7rd (7)) and under the control of which last-mentioned pulse train the speed of the driving motor is set to a value at which the speed rt of the winding spindle is equal to said sum.

24. The apparatus of claim 23 in which said control means further comprises an automatic control loop in which the driving motor is included, the controlled quantity of the loop forming the speed of the winding spindle, the control loop also includes a digital automatic controller and a detecting element of said controller, said pulse source emitting pulses having a repetition frequency that is proportional to the actual value n of the speed of the winding spindle, the pulse train from the summing device being applied to a second input of said comparing element, and in the case of a difference registered by the comparing element between the repetition frequencies of the pulses applied thereto the control loop varies the speed of the driving motor so that said difference is reduced.

25. The apparatus of claim 23 in which said means for feeding yarn includes a drawing apparatus provided with at least one feed roller and one draw roller, and said second pulse source being coupled to one of the rollers of the drawing apparatus.

26. The apparatus of claim 25 in which the second pulse source is coupled to the draw roller.

27. The apparatus of claim 21 in which said control means includes a driving motor for driving the winding spindle, a pulse source which emits pulses having a repetition frequency which is proportional to the actual value 11 of the speed of the winding spindle, a second pulse source which emits pulses having a repetition frequency which is proportional to the rate V(v) at which the yarn is fed to the twisting apparatus, a second pulse divider to which these pulses are applied, the frequency division of said second pulse divider, under the control of the programming unit, being set to a value corresponding to the value 1rd(v), so that the repetition frequency of the pulses emitted by said second pulse divider is proportional to V(v)/1rd(v) where d(v)=the yarn package diameter corresponding to the value v of the progress variable; a substraction device to which is applied the pulses having a repetition frequency which is proportional to the actual value n of the speed of the winding spindle and one of the two series of pulses having .a repetition frequency which is proportional to n (v) and V(v)/ 1rd (v), respectively, said subtraction device emitting pulses the repetition frequency of which is proportional to the difference of the repetition frequencies of the pulses applied thereto, the driving motor being included in an automatic control loop of which the controlled quantity is formed by V(v)/1rd(v) and n (v), respectively, the control loop also including a digital automatic controller, the comparing element of which makes a frequency comparison of the series of pulses from the subtraction device with the series of pulses having a repetition frequency which is proportional to V(v)/1rd(v) and n (v), respectively,and when in the case of a frequency difference between the compared pulse trains, the control loop varies the speed of the driving motor so that said deviation is reduced.

28. The apparatus of claim 21 in which the first pulse source is formed by an electronic pulse generator with variable frequency.

29. The apparatus of claim 20 in which said control means includes a means for forming a quantity proportional to the feed rate of the yarn supplied to the twisting apparatus and a control element through which the programming unit is controlled by said quantity whereby the programme is executed in a period of time proportional to said feed rate.

30. The apparatus of claim 29 in which last mentioned means comprise a pulse source for applying to the control element, pulses having a repetition frequency which forms the control quantity proportional to the feed rate of the yarn.

31. The apparatus of claim 30 in which said means for feeding yarn includes .a drawing apparatus provided with at least one feed and one draw roller, and said pulse source is coupled to the draw roller.

32. The apparatus of claim 30 in which the control element is an electric stepping drive.

33. The apparatus of claim 30 in which an .adjustable pulse divider is provided through which the pulse source is connected to the control element.

34. The apparatus of claim 20 in which the means for feeding the yarn to the twisting device includes a drawing device provided with at least one feed and one draw roller, the draw roller being coupled to a drive, the rotary speed of which is variable independent of the winding spindle.

35. The apparatus of claim 34, in which the drive of the draw roller comprises a driving motor with variable speed.

36. The apparatus of claim in which the driving motor is included in an automatic control loop, the controlled quantity of which corresponds to the speed of this driving motor, the control loop also including an automatic controller and a detecting element for the speed of the driving motor, said element being connected to a first input of said controller.

37. The apparatus of claim 36 in which said control means includes a digital automatic controller, and said detecting element is formed by the second pulse source.

38. The apparatus of claim 37 in which the second input of the digital automatic controller is connected to the first pulse source which applies pulses to said controller, the repetition frequency of which represents the desired value of the speed of the driving motor.

39. The apparatus of claim 38 in which at least one of said two inputs of the automatic controller is connected to a pulse divider with adjustable frequency division.

40. The apparatus of claim 20 in which said means for feeding yarn to the twisting device includes a drawing apparatus provided with at least one feed roller and one draw roller, said feed roller being coupled to a drive whose rotary speed is variable independent of the speed of the winding spindle.

41. The apparatus of claim 43 in which the feed roller is coupled to a drive, the speed of which is variable independent of that of the drive of the draw roller.

42. The apparatus of claim 41 in which the drive of the feed roller comprises a driving motor with variable speed.

43. The apparatus of claim 42 in which the driving motor of the feed roller is included in an automatic control loop, the controlled quantity of which corresponds to the speed of the driving motor, the control loop also including an automatic controller and a detecting element for the speed of the driving motor, said detecting element being connected to a first input of said controller.

44. The apparatus of claim 43 in which the automatic controller is a digital automatic controller and the detecting element is formed by a pulse source coupled to the driving motor of the feed roller, which supplies pulses having a repetition frequency which is proportional to the speed of the driving ;motor.

45. The apparatus of claim 44 in which a second input of the digital automatic controller is connected to a second pulse source, which applies pulses to said controller, the repetition frequency of which represents the desired value of the speed of the driving motor for the feed roller.

46. The apparatus of claim 45 in which a pulse divider with adjustable frequency division is connected to at least one of said two inputs of the .automatic controller for the driving motor of the feed roller.

References Cited UNITED STATES PATENTS

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