US3325985A

US3325985A - Draw-twisting method and yarn tension adjusting apparatus

Info

Publication number: US3325985A
Application number: US340083A
Authority: US
Inventors: Bucher Erich
Original assignee: Zinser Textilmaschinen GmbH
Current assignee: Oerlikon Textile GmbH and Co KG
Priority date: 1963-01-30
Filing date: 1964-01-24
Publication date: 1967-06-20
Anticipated expiration: 1984-06-20
Also published as: DE1273389B; CH422215A; GB1023103A

Description

June 20, 1967 E. BUCHER 3,325,985

DRAW-TWISTING METHQD AND YARN TENSION DJUSTING APPARATUS Filed Jan. 24, 1964 6 Sheets-Sheet l E. BUCHER -,ulne 20, 1967 DRAW-TWISTING METHOD AND YARN TENSION ADJUSTING APPARATUS 6 Sheets-Sheet 2 Filed Jan. 24,11964 (5 n fik-@QJ J. fweef June 20, 1967 E. BUCHER v 3,325,985

DRAW-TWISTING METHOD AND YARN TENSION ADJUSTING APPARATUS Filed Jan. 24, 1964 6 Sheets-Sheet 3 Inventor:

H46 @lah/- f man] x ffhfg,

June 20, 1967 E. BUCHER 3,325,985

DRAW-TWISTING METHOD AND YARN TENSION ADJUSTING APPARATUS Filed Jan. 24, 1964 l 6 Sheets-Sheet 4 Inventor: 'gf/'4f BMA@- June 20, 1967 E. BUCHER 3,325,985

DRAW-TWISTING METHOD AND YARN TENSION ADJUSTING APPARATUS Filed Jan. 24, 1964 6 Sheets-Sheet r Fig. 6c

t1 t3 la `lune 20, 1967 E. BUCHER 3,325,935

DRAW-TWISTING METHOD AND YARN TENsloN ADJUSTING APPARATUS Filed Jan. 24, 1964 6 Sheets-Sheet 6 F Fig. 8

182 l/.v/' f 1a1 t1 tl,

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United States Patent O 3,325,985 DRAW-T'WlSTING METHOD AND YARN TENSION AEJUSTING APPARATUS Erich Bucher, Goppingen, Wurttenrberg, Germany, assignor to Zinser-Textilrnaschinen Gesellschaft mit beschrankter Haftung, Ebersbach (Fils), Germany Filed Jan. 24, 1964, Ser. No. 340,083 Claims priority, application Germany, Jan. 30, 1963,

9,884 31 Claims. (Cl. 57-93) The present invention relates to a draw-twisting method and to a yarn 1 tension :adjusting apparatus which is used in carrying out the method of the invention. More particularly, the present invention relates to an arrangement according to which single yarns consisting of a synthetic material are wound on a rotating bobbin after being drawn out 2 and then twisted by means of a traveler running around a twisting ring.

Known draw-twisting apparatus of this type uses bobbins rotated by spindles at a constant speed. The speed of the traveler is substantially smaller at the beginning of a winding operation than at the end of the winding operation due to the fact that the dia-meter of the package wound on the bobbin is continuously increased and that the twist given to the yarn by the twisting operation is not substantial. The speed of the traveler must not exceed a certain upper limit since excessive traveler speeds result in damage to the traveler and also in unduly high tension of the yarn during the twisting and winding operation. High yarn tension results in undesired stretching of the yarn which reduces the usefulness of the twisted yarn. Due to these reasons, known draw-twister or drawtwisting apparatus provides a constant rotary speed of the spindle which is only so high that the traveler speed at the end of the winding operation when the diameter of the package is greatest, substantially corresponds to the maximum speed permissible for the traveler. During the first part of the winding operation, the traveler speed is consequently substantially below the permissible upper speed limit so that the draw-twis-ting machine does not operate at full capacity, and the yarn is not wound at the highest permissible speed during the first part of each winding operation by which -a package is wound on a spindle.

It is one object of the present invention to overcome this disadvantage of known draw-twisting machines, and to provide a method and apparatus for winding a yarn on a bobbin at the highest desired winding speed during the entire winding operation.

Another object of the present invention is -to rotate the bobbin, and the spindle carrying the bobbin, at a varying speed to compensate for the increase of the winding speed and of the traveler speed caused by the gradually increasing diameter of the wound package.

Another object of the present invention is to maintain the yarn tension of a yarn wound in a draw-twister or draw-twisting machine on a bobbin at predetermined desired values during the entire winding operation.

Another object of the invention is to control the twisting `and winding operation in such a manner that the yarn tension varies during the winding operation in accordance with a predetermined function.

Another object of the invention is to control the rotary speed of the bobbin during the winding operation in accordance with a predetermined program representing a 1The expression yarn to be interpreted in the entire specification und claims as a Continuous filament or a plurahty of filaments in forni of a continuous lainent yarn.

2 The expression drawn out to be interpreted in the entire specification and claims as stretching or drawing the filament or filament yarn to an increased length.

Lit)

fice

desired function according to which the rotary speed of the bobbin is to vary during the winding operation.

Another object of the invention is to control the rotary speed of the bobbin in accordance with the actual tension of the yarn during the twisting and Winding operation.

Another object of the present invention is to wind a yarn on a bobbin in a draw-twisting machine in such a manner that yarn portions located in superimposed layers of the pack-age have different predetermined tensions.

With these objects in View, the present invention relates mainly to an arrangement in which the tension of a yarn which is wound on a bobbin in a draw-twisting machine is regulated or controlled in accordance with a predetermined function.

In such an arrangement, it is possible to vary the tension of a yarn durin-g a winding operation in such a manner as required by the technological and physical properties of the yarn, and by the properties desired of the wound package.

Particularly, the function, which may be graphically represented, can be determined in such a manner that undesired high yarn tensions, which may be produced by a stretching of the yarn during the twisting operation, are prevented for all practical purposes.

For example, the function may be selected in such a manner that the yarn tension is slightly below the maximum permissible yarn tension which is given by the physical and technological properties of the respective yarn. It is, however, a prerequisite for such a determination of the yarn tension that the speed of the traveler does not exceed the maximum permissible speed. Consequently, the maximum yarn tension must be determined in view of the maximum permissible traveler speed.

The function according to which the yarn tension is to be controlled, may be at least during part of the winding operation maintained at a constant level.

It has been found that the function can be selected in such a manner that the feeding speed of the drawingout device through which the yarn passes before being wound on a bobbin, and there-by the entire output of the draw-twisting machine can be increased without any detrimental effects on the yarn package. The feeding speed may be maintained constant during each winding operation. This corresponds to a variation of the rotary speed of the spindle supporting the bobbin, which results in diterently twisted yarn portions, but it has been found that such differences in twist are without any practical consequences as compared with the advantage of increased production of the draw-twisting machine, and the improved technological properties of the drawn-out and twisted yarn.

In accordance with the present invention, the function according :to which the yarn tension varies can be selected in such a manner that certain undesired properties of the finished package Iare avoided. For example, in packages wound in accordance with the prior art, a relaxation or shrinking of the yarn lin the package takes place in accordance with the position of yarn portion on Ia smaller or larger diameter of the package. In accordance with the invention, such differences can be compensated partly or completely by controlling or regulating the yarn tension during the winding operation.

In accordance with one embodiment of the invention, the yarn tension is controlled or regulated in accordance with a predetermined function during the winding operation, and particularly during the second half of the winding operation.

During the rst half of the winding operation, the yarn tension may be substantially maintained at a high constant value, and in many cases it is desirable to reduce this yarn :tension during the rst part of the winding operation.

By controlling the yarn tension in this manner at least during part of the winding operation, particularly at the beginning, the present invention accomplishes the result that the outwardly lying yarn loops of the package will not slip out of position when the yarn is wound off the package. In packages wound in accordance with the prior art, the outermost windings of the package frequently slip across, or `between other windings, since the yarn is 4wound at high tension. Furthermore, the cornparatively soft consistency of the inner part of the wound package, caused by low yarn tension at the beginning of the winding operation in accordance tothe prior art, permits the entering of outer windings between adjacent inner windings. In accordance with the present invention, the yarn tension is high particularly at the beginning of the winding operation when the inner part of the packagel is being wound, so that `the latter is correspondingly more rigid and consequently will not permit the entering of outer yarn windings between adjacent windings of the inner part.

In accordance with a preferred method and apparatus according to the present invention, the yarn tension is controlled in accordance with a predetermined program, which is advantageously represented by a program carrier, such as a card read out by program controlled means. The yarn tension is continuously sensed during the winding operation, and the sensed actual yarn tension compared with a desired yarn tension represented by the program. As long as the actual value and the program represented desired value of yarn tension differ, the rotary speed of the bobbin carrying spindle is varied in such a manner that the difference between the value is reduced. This method permits ra particularly exact regulation of the yarn ytension in accordance with a predetermined function represented by the program.

If it is desired to have the yarn tension constant, then the regulation in accordance with a function represented by a program can be omitted, and the sensed actual yarn tension compared with Ia constant desired and selected yarn tension. Such comparison of the actual yarn tension with a desired yarn tension following a function represented by a program, or being constant, is preferably carried out by an electronic comparison device.

In thefevent that the regulation of the yarn tension takes place in accordance with a function represented by a program, the respective function constitutes a variation of the desired tension during the winding time. Since information regarding the actual yarn tension is compared with information represented by a program, this type of regulation may be considered as a feedback regulation.

A draw-twisting machine has a great number of spindles which are all simultaneously rotated. In accordance with the present invention, it is preferred to determine the yarn tension only at a single winding station by a sensing means engaging one yarn wound on a bobbin, and to control the rotary speed of all spindles of the machine in accordance with the rotary speed determined by the apparatus of the invention for a single spindle.

Since the yarn tension is partly dependent on the friction between the traveler and the twisting ring, and since such friction may vary at different twisting spindles, it follows that the yarn tension may be different at different spindles. However, it has been found that such differences of the yarn tensions at `different twisting stations are comparatively insignificant so that it is sufficient to regulate or control the yarn tension -of all twisting stations in accordance with the values determined for one characteristic twisting station.

In accordance with another embodiment of the invention, the yarn tension is not sensed, but the rotary speed of the spindle is regulated or controlled in accordance with a program which has been empirically found to result in yarn tension following 'a desired function, and in a package having the desired properties. In this elmbodiment as well, the small frictional differences between the individual twisting stations are of no consequence, and all twisting stations and spindles of the machine can be controlled in accordance with a program represented by a single program carrier.

The yarn tension discussed above is the tension of the yarn portion between the drawingout device and the bobbin during a twisting operation. It has been found that this tension is not constant over the entire length of the respective yarn portion. The yarn tension between the drawing-out device and the travelery is Adifferent from theV yarn tension between the traveler and the bobbin. in accordance with the present invention it is preferred to regulate or control the rotary speed of the spindles in accordance with the yarn tension prevailing between the drawing-out devicer and the traveler, and more particularly between the drawing-out device and the thread guide located in the axis of the 'bobbin and spindle.

Such an arrangement has particularly` good results concerning a high feeding speed of the drawing-out device, and good technological properties of the drawn-out and twisted yarn.

However, if it is desired` that under no circumstances a certain maximum tension between drawing-out device and bobbin is exceeded, which may occur with very fine delicate yarns, then the yarn tension between bobbin and traveler may be sensed for controlling the winding and twisting operation.

If it is not desired to regulate the yarn tension, but to influence the rotary speed of the spindle depending on the program, the rotary speed of the spindle can be regulated or controlled in accordance with the program. If the rotary spindle speed is to vbe regulated, information regarding the actual spindle speed is fed back into comparison device which also receives a signal corresponding to a desired rotary speed in accordance with a program. Differences between the desired program represented speed and the actual speed of the rotary spindle, produce a command signal by which the spindle speed is adjusted. Under certain circumstances, it is not necessary to regulate the rotary speed of thespindles in this manner, andy it is sucient to control the rotary speed in accordance with a program. In this event, the motor driving the rotary spindles is adjusted in accordance with a program which represents the preselected and desired rotary spindle speeds during each moment of the winding operation.

The function according to which the rotary speed of the spindles is to `be controlled by the program need be determined only once for a particular batch of yarn. The yarn is wound on the bobbin of the draw-twisting machine, while the yarn tension is regulated manually or automatically .in such a manner that the yarn tension varies in accordance with` a desired function. At the same time, the rotary speed of the spindle is continuously registered and recorded. On the basis of the recorded values of the rotary spindle speeds, the program function for the program regulation or progam control of the rotary spindle speed is determined. A record carrier is provided with records representing the thus empirically determined function, and during future winding operations, the rotary speed is controlled or regulated in accordance with the function represented by the program. j Ring spinning machines are known in which the speed of the spinning machine is controlled during each spinning Operation in such a manner that peaks of the yarn tension are avoided to prevent yarn breakage. However, this method in which the feeding speed of the drawing devices is varied at the same` time and together with the rotary speed of the spindles and with the frequency of the spinning ring operation, and in the same ratio, cannot be used with a draw-twister or a draw-twisting `machine of the type with which the present invention is con- Cerned in which a lament yarn is stretched or drawn out and wound to form a package on a bobbin. It has been found by tests, that when the method of the prior art is used for a machine of the type with which the present invention is concerned, the technological properties of the stretched and twistedyarn are detrimentally effected to such an extent that the yarn produced is useless for most purposes. In contrast thereto, the method of the present invention improves the technological properties of the yarn substantially, and moreover causes a substantial increase of the output of the machine.

In order to simplify the program control or program `regulation of the rotary spindle speed, it is advantageous in certain cases to vary the rotary spindle speed during at least part of the winding time substantially in accordance with a linear function. The arrangement is further simplified if the rotary spindle speed is maintained constant during at least a part of the winding time.

In the preferred arrangement of the present invention, the rotary spindle speed is reduced from a maximum value at the beginning of the winding operation to a yminimum during the second half of the winding time,

particularly between two thirds and three quarters of the Winding time. It is advisable to continuously reduce the rotary spindle speed, and particularly advantageous to gradually reduce the rate at which the spindle speed is reduced so that the minimum spindle speed is approached in an asymptotic manner. After the minimum spindle speed has been reached and maintained for a time period, it is in many cases advantageous to again increase the spindle speed at the end of the winding time, either continuously or stepwise.

A method for draw-twisting yarn according to the present invention comprises the steps of drawing-out a yarn; rotating a bobbin and winding the drawn-out yarn onto the bobbin so that a portion of the yarn supplied to the 4bobbin is tensioned as a yarn package of increasing diameter is formed on the bobbin; and automatically varying the rotary speed of the bobbin to maintain the tension of the yarn at predetermined desired values while the diameter of the package increases. As explained above, the predetermined value may be a constant value, or a value -depending on a selected function achieving different and varying yarn tensions during successive parts of the Winding operation.

According to one method of the invention, the yarn tension is sensed, and the sensed tension is compared with a predetermined desired tension whereupon the rotary speed of the bobbin is automatically regulated until the sensed tension is substantially equal to the predetermined tension.

According to another method of the invention, the actual rotary speed of the bobbin is compared with a program representing a predetermined characteristic function of a rotary bobbin speed over the winding time, and the rotary speed of the bobbin is regulated until the bobbin speed is substantially equal to the program represented speed at the same moment. In accordance with another method of the present invention, the rotary speed of the bobbin is automatically controlled in accordance with anempirically determined program representing a selected characteristic function of the rotary speed of the bobbin over the windin g time.

An apparatus according to the invention comprises a drawing-out device; a rotary spindle; a twisting ring surrounding the spindle and a traveler mounted for movement along the twisting ring; drive means rotating the spindle so that yarn supplied from the drawing-out device is wound up on the bobbin to form a package of gradually increasing diameter; adjusting means, preferably including a servomotor controlling an electric motor forming part of the drive means to adjust the motor speed and thereby the rotary spindle speed; and operation controlling means for automatically actuating the servomotor of the adjusting means so that the rotary speed of the spindle is varied 6 during the Winding operation in such a manner that the tension of the yarn between the bobbin and the drawingout device is maintained at predetermined desired values while the diameter of the package increases during the winding operation.

In one embodiment of the invention, a sensing means for sensing the yarn tension is provided and produces a signal proportionate to the sensed tension. The signal is supplied to a comparison device to which a comparison signal is supplied representing a desired tension. The comparison device produces a command signal representing the difference between the actual tension and the desired tension at the respective moment, and such signal is used to control the servomotor of the actuating means to adjust the rotary spindle speed.

The comparison signal may be constant and represent a constant desired yarn tension, or may be varied in accordance with the function represented by a program readout by a program controlled device from a record carrying card.

In another embodiment of the invention, no sensing means is provided, and the comparison device is supplied with a signal representing the actual spindle speed which may be measured by a tachometric device producing a signal whose voltage is proportionate to the actual rotary speed of the spindle and bobbin.

Instead of regulating the machine in this manner, it may be considered suliicient to control the machine directly in accordance with a program, and in this event the operati-on control means include a program controlled means producing signals representing a desired variation of the rotary speed of the spindle during a winding operation, and such signals are used for adjusting the drive motor of the spindle.

In the embodiment using a comparison device, information about the actual conditions is fed back to be compared with a desired value represented by the program.

In one embodiment of the invention, the servomotor is controlled to adjust the position of the brushes of the motor of the drive means. In another embodiment of the invention, the motor of the drive means runs at constant speed, and a gradually variable transmission, provided between the motor and the spindles, is adjusted by the servomotor.

In the preferred embodiment of the invention a program card of plastic synthetic material provided with ridges is used. However, a magnetic record carrier or a perforated tape may be used as program carrier.

A program function represented by a program card is designed to represent the rotary winding speeds during a single winding operation in which a complete package is wound on the bobbin of each spindle of the machine. A program function empirically determined, and a corresponding program carrier, can then be used again repeatedly for other winding operations with empty bobbins replacing the ybobbins on which packages have been completely wound, assuming that the yarn Wound during the second winding operation has the same technological and physical properties, and that the same type of package is desired.

However, it has been found that a program function determined for a certain yarn cannot only be applied t0 the yarn which was used for empirically determining the program function, but can be used for a number of somewhat diiferent yarns having different yarn numbers or consisting of a somewhat different material.

Generally, a number of record carriers with different empirically determined programs will be available, and each program is suitable for a group of yarns which may be slightly different from each other.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be d best understood from the following description of specic embodiments when read in connection with the accompanying drawings, in which:

FIG. 1a is a perspective view illustrating a draw-twisting machine or draw-twister provided with the yarn tension adjustingr apparatus according to one embodiment of the invention;

FIG. lb is a fragmentary perspective view illustrating the yarn tension adjusting apparatus of the embodiment of FIG. la on a larger scale;

FIG. 2 is a fragmentary schematic perspective View illustrating the apparatus of the embodiment of FIGS. la and 1b, with parts of the machine omitted for the sake of clarity;

FIG. 3 is a fragmentary schematic perspective view illustrating a modified embodiment of the apparatus of the invention;

FIG. 4 is a fragmentary schematic perspective view illustrating another embodiment of the invention;

FIG. 5a is a perspective view illustrating 'a program carrying card used in the l'apparatus of FIG. 2;

FIG. 5b is a cross-sectional view taken on line 5-5 in FIG. 5a;

FIG. 5c is a diagram illustrating the program represented by lthe card shown in FIGS. 5a and 5b in the form of a graph;

FIG. 6a is a perspective view illustrating a program carrying card used in ythe embodiment of FIG. 3;

FIG. 6b is a cross-sectional view taken on line 6-6 `in FIG. 6a;

FIG. 6c is a diagram illustrating the program of the` card shown in FIGS. 6a and 6b in the form of a graph;

FIG. 7 is a diagram illustrating variations ofthe rotary speed of the spindles automatically carried out in yaccordance with the present invention;

FIG. 8 is a diagram illustrating several yarn tensions automatically varied Vand adjusted in accord-ance with the invention; and

FIG. 9 is a fragmentary schematic perspective view illustrating another embodiment ofthe invention.

Referring now to the drawings, Kand more particularly to FIGS. 1a, 1b and 2, the draw-twisting machine shown in FIG. la comprises a hea-d stock 10, a tail stock 12, a base 14, and a series of twisting devices arranged in two parallel rows at the front and rear of the machine. The machine is particularly suited for the twisting of synthetic fibers rwhich are stretched or drawn out. Only a single yarn 11 is shown in FIG. 1a, but it will be understood that two rows of supply spools are disposed on `a support, not shown, mounted on carrier rods 15. Each yarn 11 is guided over a roller 16 and a plurality of guide roller means 13 which assure the transport of the yarn which then passes between Iroller 16 and a roller 30.

The yarn is then fed in the direction of the arrow A in FIG. 1 to a roller 18 and `another roller 20 over which the yarn is guided in several loops. The peripheral speed of roller 18 is greater than the peripheral speed of roller so that the yarn is stretched or drawn out by the

device

13, 16, 30, 18, 20, as is known to those skilled in the art.

The drawn-out yarn :is guided through a thread guide 47 in the form of an eye disposed in the axis of a rotary twisting device 22 which includes a rotary spindley 24 having a vbobibin-supporting shaft 5l), ya twisting 4ring 35 surrounding a bobbin mounted on the spindle, and a traveler 21 mounted on the twisting ring 35. When the spindle is rotated, the bobbin rotates so that the yarn passing `through thread guide 47 and traveler 21 is wound in a package on the bobbin. The support 75 moves twisting ring 35 in `:atxialdirection in a reciprocating motion whose stroke is gradually reduced during the winding operation so that the package has conical end portions, as is known to those skilled inthe art.

Every spindle 24 has a spindle lbody 58 with la pulley portion 55. In the embodiment shown in FIG. 2, a belt 3 57 is guided over the pulleys of four spindles' and over a pair of guide rollers 51, 52, to a drive pulley 2S on drive shaft 27. Groups of spindles comprising two forward and two rearward spindles are driven in this manner from drive shaft 27 by driving devices generally indicated by a reference numeral 48.

Drive shaft 27 is driven by an electric drive motor 26 mounted in the head stock 10 of the machine.

Another motor 36 is connected by a belt and pulley drive 38 to a shaft 39 which drives the rollers 18 of the drawing-out device through pairs of

bevel gears

43, 44.

Shaft 39 carries the bevel gears 43 for the drawing-out devices located in the front row, and a shaft 42 drives corresponding rollers of `the rear row, as best seen in FIG. 2. A transmission gear arrangement generally indicated by reference numeral 40, is driven from a gear 39a on shaft 39 and transmits rotary motion to shaft 42, and 4the two shafts by which the

transportingV rollers

30 and 31 are driven.

In draw-twisting machines of the above described type according to the prior lart, `the spindles are rotated at a constant speed. During the rst pia-rt of the winding operation, the speed of traveler 21 is lower than during the second `part of the winding operation due to the smaller diameter of ythe wound package andthe low twist of the yarn. The speed of the traveler must not exceed a certain upper limit since very high traveler speeds' result in breakage of the yarn, or at least in undesirably high tension of the yarn wound on the package. When the tension near the end of the winding operation of the package is too high, the yarn is stretched beyond its desired stretching previously produced, and the quality and usefulness ofthe yarn will be impaired. Consequently, a constant spindle speed must be selected in such a manner that the speed of the traveler at the end of the winding operation corresponds substantially to the maximal permissible upper limit. As a result, the traveler speed is substantially below the permissible limit during the first part of the winding `operation so that the draw-twisting machines according to the prior art are not fully used since a lesser amount of yarn is drawn-out and wound up in a given time than could be wound if the spindles would rota-te at maximum speeddu'ring the first part of the winding operation.

In accordance with the present invention, the rotary speed of the spindles is adjusted, controlled or regulated, so that the maximum ou-tput of the machine can be achieved. The speed of the spindle is varied in such a manner that the tension of the yarn is maintained at predetermined desired values which may follow ia certain function, or which may be a constant tension.

In lthe embodiment of FIGS. la, lb and 2, the rotary speed of the spindles iis regulated in accordance with a program represented by the card shown in FIGS. 5a and 5b, and the variation of the Irotary speed of the spindle over the time of winding is represented by the graph shown in FIG. 5c.

The electric motor 26 of the spindle drive means includes a servo-motor by which a device for adjusting the position of the brushes of motor 26 is operated to gradually and continuously adjust the rotary speed of motor 26 and thereby of drive shaft 27.

A gear transmission 81 drives a tachometric means 82 which produces an electric signal whose voltage is proportionate to the rotary spindle speed. Two

terminals

83 and 84

secure conductors

87 and 90 which respectively lead to an indicator 89 and to a comparison device 91 of known construction. The spindle speed is indicated by indicator 89 to the operator.

Program controlled means 94 are provided for sensing a program carrying card 97, and produce a second signal whose voltage is proportionate to the desired rotary speed at any time during the winding operation. The signal is supplied through conductor 92 to comparison device 91 and compared with the signal from the tachometric means 82 which represents the actual value of the rotary speed. The comparison device 91 compares the actual value with the programmed desired value of the speed, and if the two values are not identical, a command signal is produced and transmitted through conductor 96 to servomotor Si) to adjust the rotary speed of the motor 26. Motor 26 is adjusted until the difference between the actual speed and the programmed speed is below a predetermined small value, which is zero for all practical purposes but is selected to prevent hunting.

As best seen in FIGS. a and 5b, the program carrying card 97 has at its upper edge a rack 99a whose gear teeth are engaged by a transporting roller, not shown, so that card 97 is continuously advanced during a winding operation.

Card 97, which is made of a synthetic plastic material, has live longitudinal columns 991) to 99f of which columns 99C to 99j have ridges of different lengths and spacing, while column 99h has one continuous ridge.

The ridges represent in a certain sense orders of desired rotary speeds. For example, the column 99h is associated with 6,000 revolutions per minute, column 99e is associated with 1,000 revolutions per minute, column 99d is associated -with 500 revolutions per minute, column 99e is associated with 320 revolutions per minute, and column 99f is associated with 160 revolutions per minute.

T he number of revolutions at any moment of the winding operation is rep-resented by the ridges located in a line across the card. For example, at the line (1, ridges are provided in all tive columns, and consequently a sens- .ing feeler 98 located across the card, will produce a signal whose voltage represents a number of revolutions which is 6,000-|1,000+500+320+160, which are 7,980 revolutions per minute. When the card has traveled further, and the sensing feeler is at the line b, the program voltage represented by the card is 6,000-i-500-i-320 which are 6,820 revolutions per minute. The program determined rotary spindle speeds are represented in FIG. 5c by the number of revolutions n over the time of winding t. It will be seen that in accordance `with the function represented by the graph of FIG. 5c and by the program on card 97, the rotary speed of the spindle is reduced during the first part of the winding operation lasting to the time I2, then maintained at a constant level to the time t3, and then increased again to the time t4 of the end of the winding operation.

The stepped graph 99m represents the effective values, and the broken line graph 99p represents average values.

The function represented by the graphs of FIG. 5c is empirically determined and results in wound packages having the desired tension in all layers, while the yarn is not unduly stretched during operation of the machine at very high winding speeds.

In accordance with conditions prevailing during a drawing-out and twisting operation, the technological and physical properties of the yarn, and the desired properties of the wound package, the program may be modified to achieve the desired result. However, at least during the first part of the winding operation, the rotary spindle speed is gradually reduced, and it has been found advantageous to operate the spindles at a substantially constant speed during the middle part of the winding operation. The increase of the winding speed at the end of the winding operation as described with reference to FIG. 5c, may not be necessary and in this event the winding is preferably carried out at a constant speed to the end of the winding operation.

It will be understood that at the time t1 indicated in FIG. 5c, the bobbin is empty an-d that the diameter of the wound package continuously increases during the winding operation while the rotary speed of the spindle is reduced. The diameter of the package continues to increase while the rotary speed of the spindle is maintained at a constant level, or again increased as described with reference to FIG. 5c.

In the embodiment described with reference to FIGS. la, lb, 2 and 5a to 5c, the rotary spindle speed is regulated in accordance with a program. It is, however, in certain cases sufficient to control the speed of the spindles in accordance with a program, and such a simplified arrangement is illustrated in FIG. 3.

The drive motor 26, and the adjusting means with servo-motor correspond to the embodiment described with reference to FIG. 2. However, the comparison device is omitted, and the program controlled means 102 with sensing feeler 105 produce a voltage signal by sensing the program on card 104, and such signal, which represents the speed of the spindle in accordance with the program, is supplied to the servo-motor 80 which correspondingly adjusts the motor speed.

FIGS. 6a and 6b illustrate a program card 104 used in the program controlled means 102. A rack 106 is provided along one longitudinal edge of the card so that the card can be transported by a suitable gear roller. Three columns 10561, 105]) and 105C contain ridges, column 105a having spaced ridges 105m, and column 105b having a single ridge extending along the length of the card. The ridge of column 105C is continuous, but shorter than the ridge of column 105b.

In contrast to the card described with reference to FIGS. 5a and 5b, the several ridges of the card 104 are not all associated with the rotary spindle speed. The ridge in column 105C controls the start and stopping of the twisting machine, which will be operative as long as the ridge in column 105C is sensed by the sensing feeler 105.

The several ridges 105m in column 105a and the ridge in column 105b are associated with the speed control. Whenever the sensing feeler engages one of the ridges 105m the servo-motor S0 is energized to actuate the adjusting means so that the speed of motor 26 is varied for a predetermined amount, for example 35 revolutions per minute. This adjustment is additive and results in a speed increase if no ridge is provided in column ItiSb in the respective transverse line in which the sensing feeler operates, and is negative if a ridge portion is present in the respective part of column 105i). For example, along the line (1, a ridge projection is provided in col-umn 105a, and a ridge is provided in column 10517 so that servomotor 80 is controlled to effect a speed reduction of the motor 26 for 35 revolutions pe-r minute, as indicated by the steps of the graph in FIG. 6c. In the example of the control function represented by the program of the card shown in FIG. 6a, the spindle speed is not increased at the end of the winding operation, but maintained at a constant level between the time t3 and t4 at the time t3, the control by the program card is terminated so that the apparatus is only used for reducing the rotary spindle speed during the rst part of the winding operation corresponding to the increasing diameter of the bobbin package. Since the spindle speed is not to be increased, ridge 1t35b extends along the length of the card without interruption.

The function represented by the graph in FIG. 6c is also characteristic for a winding operation in accordance with the present invention. Other characteristic functions according to other programs are illustrated by

graphs

119, 120, and 121 in FIG. 7. The ordinate again represents the rotary spindle speed expressed in revolutions per minute, and the abscissa represents the winding time t. t1 is the start, and t4 is the end of the winding operation.

The function represented by graph 119 corresponds to a grad-ual reduction of the speed of the spindles at a varying rate. During the first part of the winding operation, the rotary spindle speed is gradually reduced in accordance with a non-linear function at the gradually reduced rate. In the time period between the times t2 and t3, the function is substantially linear, whereas after the time tgl, the spindle speed is maintained at a constant level to the end of the winding operation.

It has been 'found that in many cases a non-linear function represented by the program, can be replaced by corresponding linear functions, as indicated at 12). A further variation is indicated by the graph 121 and represents an increase of the rotary spindle speed at the end of the winding operation as described with reference to FIG. 5c. It has been found that the yarn wound in the package shrinks to a greater extent in the inner layers of the package, and relaxes in the outer layers of the package where the diameter is greater. By increasing the spindle speed at the end of the operation, the outer layers are wound at a desired higher tension. Graph 121 is merely illustrative, and the amount by which the spindle speed is increased at the e-nd of the operation depends on the prevailing conditions and is empirically determined. However/the increase of the spindle speed will be generally produced only during the last third of the winding operation.

The above described embodiments of the invention use a program carrier, which has been described as a cardV provided with ridges, of which evidently a perforated card or tape can be substituted` However, instead of controlling the machine operations by a program carrier, a mechanical switching mechanism may be used.

An embodiment of a mechanical switching mechanism for controlling the spindle speed as illustrated in FIG. 9. FIG. 9 only i-llustrates the control mechanism, and the other parts of the machine correspond to FIGS. la, 1b,

kand 2. The drive motor 26 kdrives through a drive shaft the spindles on which the bobbins are located, and the yarn is supplied as described with reference to FIG. lb.

An adjusting means for motor 26 includes a servo-motorl 80 which, whenever, energized, will adjust the motor speed, and thereby the rotary speed of the spindles. Servomotor 8) is connectedl by conductor 123 and conductor 124 to a voltage source 125, a switch 126 being provided in conductor 124 `and adapted to interrupt the connection between the voltage source and servo-motor 80.

A synchronous motor 130 drives through a reduction transmission 127 including gears 137 and 13S, a cam disk or switch actuator 132 to which a plurality ofcam lugs 133 are detachably attached. Cam lugs 133 cooperate with a projection 135 of switch 136 to close switch 136 whereby the servo-motor 80 is energized, and the speed of the motor 26 is adjusted.

Whenever a cam lug 133 closes switch 136, the rotary speed of motor 26 is reduced the same amount, for eX- ample 50 revolutions per minute. A program is selected -by placinly a selected number of cam lugs at selected positions circumferentially spaced from each other on the outer periphery of disc 132.

lBy exchanging gears

138, 137, the rotary speed of

cam

132, 133 can be adjusted and the time during which a program represented by

cam

132, 133 is carried out, can be varied.

Generally, one full rotation of cam disc 132 will correspond to the time required for the program-controlled winding operation. However, a program may be carried out while disc 132 performs several revolutions.

In the above described embodiments, the rotary speed of the spindles is varied in accordance with a program which is empirically determined. In the embodiment of FIG. 4, the rotary speed of the spindles is regulated in accordance with the tension of the yarn which is supplied from the device 18, to the bobbin 23.

A sensing means 140 of known construction includes a feeler engaging the portion of the yarn between roller 18 and thread guide 47, and means for producing a voltage signal proportionate to the sensed tension. The signal produced by sensing means 140 passes through a conductor 141 to a comparison device 142 of known construction which is provided with an adjusting knob by which the comparison device 142` can be set to a selected constant voltage which is compared with the voltage of the signal produced by sensing means 140. In this manner the actual tension of the yarn is compared with a desired constant tension, and a corresponding command signal representing the difference between the desired value and the actual value of the tension is transmitted through conductor to a servo-motor by which a gradually variable transmission 152 is set to different transmission ratios. Transmission 152 `is driven by pulley means 159 and a belt 160 from the drive motor 26.

From this condition, the comparison device can be switched by a switch y145 to a condition in which the signal produced yby the Isensing means 140 is compared with a signal vsupplied. through a conductor 149 to the comparison device 142. A program controlled rneans 146 is controlled by a program tape, or by a card as described with reference to FIG'. v5a to produce a signal whose voltage varies in accordance with selected program during the winding operation so that the differential command signal transmitted to servo-motor 170 represents the difference between the tension desired in accordance with a predetermined program at any moment of the winding operation,` and the actual tension sensed by sensing means 140. In this manner, the tension of the wound-up thread is regulated `during the winding operation to follow a predetermined function.

The tension between

device

18, 20 Aand the thread guide 47 depends on the speed at which traveler 21 runs around twisting ring 35. The greater the speed of the traveler is, the greater is the tension of the yarn. The traveling speed of traveler 21 increases when the rotary speed of the spindle, and the diameter of the package increase. In the event that the rotary speed of the spindle remains constant during the entire winding operation, the thread tension will increase as the diameter of the package increases, and will become a multiple of the tension prevailing at the beginning of the winding operation with the empty bobbin. This undesired increase of the yarn tension on the bobbin is prevented by the apparatus of the present invention, since the thread .tension is regulated in accordance with a predetermined selected function if the comparison device is used together with the program controlled means 146, or the yarn tension is maintained at a constant level when the signal of the sensing means i-s compared with the constant voltage and the control of knob 144.

In any event, the ratio of the transmissionmeans 152 is continuously adjusted by servo-motor 170 so that the tension of the yarn corresponds to the desired valuewhich may be a constant value, or a value varying in accordance with a desired function. The actual tension of the yarn vwill during the entire winding operation substantially correspond t-o a predetermined tension. A

A drawing-out and twisting machine to which theV present invention is applied has a great number of spindles.

FIG. 4 illustrates only a single spindle driving arrangement with the associated drawing-out means. It is not necessary to provide a sensing means, and operation control means including a comparison device for each spindle station of the machine, but by sensing the tension of the yarn wound on one spindle, sufficient information for adjusting the rotary yspeed of all spindles is obtained. Therefore, drive shaft 27 is connected by gear transmission means of the type indicated at 401 in FIG. 2, to all spindles of the machine, for example as illustrated in FIG. 4 by pulley means 28 and lbelt means 57.

FIG. 8 is a diagram illustrating ythe functions according to which the tension of the yarn may be controlled. The ordinate lrepresents the yarn tension, and the abscissa represents the time of the winding operation. Graphs 180, 18.1 and 182 represent characteristic functions of the yarn tension during the winding operation. The line 181 represents a constant yarn tension, which may be achieved by setting knob 144 of comparison device 142 to a desired yarn tension. The graphs and 182 represent functions determined by programs represented by record carriers or record carrying cards, but it will be understood that other functions may be selected to be represented by a program carrier. The actual selected function will depend on the weight and material of the yarn, on the type and Weight of the traveler, on the shape and diameter of the twisting ring, on the diameter and size of the package, and other constructive features, so that it is best to determine empirically the program by which a package having the desired properties is produced. The program based on a gradually increasing yarn tension as represented by graph 182 will compensate for a certain relaxing of the yarn in the outer layers of the package, whereas the program producing a gradually lowered yarn tension as represented by graph 180 will have the advantage of a tighter inner core of windings of the package.

The embodiment of FIG. 4 produces the most exact approximation of the actual yarn tension to the programmed tension. However, in many cases it is suflicient to use the yarn tension adjusting apparatus described with reference to FIGS. 2, 3 and 9 to produce packages wound in the desired manner by merely programming the rotary speed of the spindles.

In order to achieve a substantially constant yarn tension as represented by the graph 181, it is necessary to continuously reduce the rotary speed of the spindles as indicated, for example, by the graph 119 in FIG. 7.

A particularly rigid package is obtained when the yarn tension lis reduced in accordance with the graph 180. When the tension of the inner layers of the package is greater than the tension of the outer layers, the slipping of windings of the outer layers into spaces between windings of the inner layers, which particularly may occur during the winding off of yarn from the package, is prevented. By increasing yarn tension as the winding operation progresses, as exemplified by graph 182, the relaxation of the outer layers of the yarn is substantially cornpensated. To obtain a function of the yarn tension as represented by graph 182, it is generally necessary to first reduce the rotary speed of the spindles, and then increase the same again near the end of the winding operation as indicated by the graph portion 121 in FIG. 7.

From the above description of several embodiments of the invention, it will become apparent that in accordance with the method of the invention, the rotary speed of the bobbins, and the winding speed of the yarn is automatically varied to maintin the tension of the yarn at predetermined desired values while the diameter of the package increases. Such predetermined value may either be a constant yarn tens-ion, or ya-rn tensions varying in accordance with a predetermined function.

It will be understood that the yarn tension adjusting apparatus of the invention comprises adjusting means,

including a servo-motor 8() for adjusting the speed of the drive means 26 and thereby the rotary speed of the spindles and the winding speed of the yarn. Operation control means may include a comparison device 91 and program controlled means 94, or be of a simpler construction and include only program control means for influencing the servo-motor 80 by the records of a program card 104.

While in the embodiment of FIG. 2, the comparison device receives a signal representing the rotary speed of the spindles, in the embodiment of FIG. 4 the control signal Arepresnts the tension of the yarn.

It will be understood that each of the elements described above, or two or more together, may also nd reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intotended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

l. A method for draw-twisting a yarn comprising the steps of drawing out a yarn; rotating a bobbin and winding the drawn-out yarn on the bobbin so that a portion of the yarn supplied to said bobbin is tensioned, as a ya-rn package of increasing diameter is formed on said bobbin; producing a first signal representing the rotary speed of said bobbin; producing a second signal in accordance with a predetermined function of the rotary speed of the bobbin over the winding time required for maintaining a desi-red tension of the yarn; comparing said first and second signals and producing a differential command signal; and automatically adjusting the rotary speed of said bobbin in accordance with said command signal until said lirst signal is substantially equal to said second signal so as to maintain the tension of the yarn at predetermined desired values while the diameter of the package on the bobbin increases during the winding operation.

2. A method for draw-twisting a yarn comprising the steps of drawing out a yarn; rotating a bobbin and Winding the drawn-out yarn on the bobbin so that a portion of the yarn supplied to said bobbin is tensioned, as a yarn package of increasing diameter is formed on said bobbin; sensing the tension of the yarn; comparing the sensed tension with a predetermined desired tension; and auto matically regulating the rotary speed of the bobbin until the sensed tens-ion is substantially equal to said predetermined tension so as to maintain the tension of the yarn at predetermined desired values while the diameter of the package on the bobbin increases during the winding operation.

3. A method for draw-twisting a yarn comprising the steps of drawing out a yarn; rotating a bobbin and winding the drawn-out yarn on the bobbin so that a portion of the yarn supplied to said bobbin is tensioned, as a yarn package of increasing diameter is formed on said bobbin; comparing the actual rotary speed of the bobbin with a program representing a predetermined characteristic function of a rotary bobbin speed over the winding time; and automatically regulating the lrotary speed of the bobbin until the bobbin speed is substantially equal to the program represented speed so as to maintain the tension of the yarn at predetermined desired values while the diameter of the package on the bobbin increases during the wind- -ing operation.

4. A method for draw-twisting a yarn comprising the steps of drawing out a yarn; rotating a bobbin and winding the drawn-out yarn on the bobbin so that a portion of the yarn supplied to said bobbin is tensioned, as a yarn package of increas-ing diameter is formed on said bobbin; and automatically controlling the rotary speed of the bobbin in accordance with a program representing a predetermined characteristic function of the rotary speed of the bobbi-n over the winding time so as to maintain the tension of the yar-n at predetermined desired values while the diameter of the package on the bobbin increases during the winding operation.

5. A method for drawtwisting a yarn comprising the steps of drawing out a yarn; rotating a bobbin and winding the drawn-out yarn on the bobbin so that a portion of the yarn supplied to said bobbin is tensioned, as a yarn package of increasing diameter is formed on said bobbin; producing a first signal representing the rotary speed of said bobbin; producing a second signal in accordance with a program representing a predetermined function of l the rotary speed of the bobbin over the winding time required for maintaining a desired tension of the yarn; comparing saidl first and second signals and producing a differential command signal; and automatically adjusting the rotary speed of `said bobbin in accordance with said command signal until said rst signal is substantially equal to said second signal; and automatically varying the rotary speed of the bobbin to maintain the tension of the yarn at predetermined desired values while the diameter of the package on the bobbin increases during the winding operation.

6. A method for draw-twisting a yarn comprising the steps of drawing out a yarn; rotating a bobbin and winding the drawn-out yarn on the bobbin so that a portion of the yarn supplied to said bobbin is tensioned, as a yarn package of increasing diameter is formed on said bobbin; and automatically varying the .rotary speed of the bobbin to maintain the tension of the yarn atpredetermined desired decreasing values during the first part of the winding operation while the diameter of the `package on the bobbin increases.

7. A method for draw-twisting a yarn comprising the steps of drawing out a yarn; rotating a bobbin and winding the drawn-out yarn on the bobbin so that a portion of the yarn supplied to said bobbin is tensioned, as a yarn package of increasing diameter is formed on said bobbin; and automatically varying the rotary speed of the bobbin to maintain the tension of the yarn at predetermined desired increasing values while the diameter of the package or thebobbin increases during the last p-art of the winding operation.

8. A method for draw-twisting a yarn comprising the steps of drawing out a yarn; rotating a bobbin and Vwinding the drawn-out yarn on the bobbin so that a portion of the yarn supplied to said bobbin is tensioned, as a yarn package of increasing diameter is formed on said bobbin; and automatically varying the rotary speed of the bobbin in accordance with a linear function of the rotary bobbin speed over the winding time at least during part of the winding operation to maintain the tension of the yarn at'predetermined desired values while the diameter of the package on the bobbin increases during the winding operation.

9. A method for draw-twisting a yarn comprising the steps of drawing out a yarn; rotating a bobbin and winding the drawn-out yarn on the bobbin so that a portion of the yarn supplied to said bobbin is tensioned, as a yarn package of increasing diameter is formed on said bobbin; and at first automatically varying the rotary speed of the bobbin to maintain the tension of the yarn at predetermined desired values while the diameter of the package on the bobbin increases during the winding operation, and then maintaining a constant rotary bobbin speed during the last part of the winding operation.

10. A method for draw-twisting a yarn comprising the steps of drawing out a yarn; rotating a bobbin and winding the drawn-out yarn on the bobbin so that a portion of the yarn supplied to said bobbin is tensioned, as a yarn package of increasing diameter is formed on said bobbin; and automatically varying the rotary speed of the bobbin in accordance with a non-linear function or" the rotary bobbin speed over winding time at least during part of the winding operation to maintain the tension of the yarn at predetermined desired values while the diameter of the package or the. bobbin increases during the winding operation.

11. A method for draw-twisting a yarn comprising the steps of drawing out a yarn; rotating a bobbin and winding the drawn-out yarn on the bobbin so that a portion of the yarn supplied to said bobbin is tensioned, as a yarn package of increasing diameter is formed on said bobbin; automatically reducing the rotary speed of the bobbin at the beginning of the winding operation in such a manner that a minimum rotary speed is reached during the second half ofthe winding time required for winding the package l@ whereby the tension of the yarn is maintained at predetermined ditferent values as the diameter of the bobbin increases during the winding operation.

12.. A method as set forth in claim 11 wherein the minimum rotary bobbin speed is produced in the time period between two-thirds and three-quarters of the winding time.

13. A method as set forth in claim 11 wherein the minimum rotary bobbin speed is between 50 percent and 90 percent of the maximum bobbin speed.

14. A method as set forth in claim 11 wherein the rotary bobbin speed is reduced from a maximum speed to a minimum speed at a gradually decreasing rate.

15. A method for draw-twisting a yarn comprising the steps of drawing out a yarn; rotating a bobbin and winding the drawn-out yarn on the bobbin so that a portion of,

the yarn supplied to said bobbin is tensioned, as a yarn package of increasing diameter is formed of said bobbin; automatically reducing the rotary speed of the bobbin at the beginning of the winding operation in such a manner that a minimum rotary speed is reached during the second half of the winding time required for winding the package, and automatically increasing the rotary bobbin speed at the end of the winding operation whereby the tension of the yarn is maintained at predetermined different values as the diameter of the bobbin increases during the winding operation.

16. A method for draw-twisting a yarn passing from a drawing-out device through a thread guide and a traveler on a twisting ring to a bobbin on a rotating spindle comprising the steps of drawing-out the yarn on the drawingout device; rotating said spindle so that the drawn-out yarn is wound on said bobbiny and the portion of the drawn-out yarn between said device and said thread guide is tensioned as a yarn package of increasing diameter is formed on said bobbin; and automatically varying the rotary speed of said spindle and thereby of said bobbin in accordance with a program representing a predetermined characteristic function of the rotary speed of the bobbin over the winding time to maintain the tension of the yarn at predetermined desired values while the diameter of the package on the bobbin increases during the winding operation.

17. Yarn tension adjusting apparatus for a draw-twisting machine comprising, in combination, a drawing-out device; a rotary spindle adapted to support a bobbin; a twisting ring surrounding said spindle, and a traveler mounted for movement along said twisting ring; a sensing means for sensing the tension of the yarn between said device and said bobbin, and adapted to produce a signal proportionate to the sensed tension; drive means operatively connected with said 'spindle for rotating the same so that the yarn supplied from said device through Vsaid traveler to said bobbin is wound up on said bobbin to form a package of gradually increasing diameter; adjusting means for adjusting the speedof said drive means and thereby the rotary speed of said spindle and the speed of said traveler; and operation control means including a comparison device connected to said sensing means for receiving said signal, means for producing in said comparison device a comparison signal corresponding to a selected tension, said comparison device producing a command signal representing the difference between said signals and thereby the deviation of the sensed actual tension from a desired selected tension and `being connected to said adjusting means for actuating the same in accordance with said command signal so that the rotary speed of said spindle is varied during the winding operation in such a manner that the tension of the yarn between said bobbin and said device is maintained at said selected tension while the diameter of said package increases during the winding operation.

18. Yarn tension adjusting apparatus for a draw-twisting machineV comprising, in combination, a drawing-out device; a rotary spindle adapted to support a bobbin; a twisting ring surronuding said spindle, and a traveler mounted for movement along said twisting ring; a sensing means for sensing the tension of yarn between said device and said thread guide and adapted to produce a signal proportionate to the sensed tension; drive means operatievly connected with said spindle for rotating the same so that the yarn supplied from said device through said traveler to said bobbin is wound up on said bobbin to form a package of gradually increasing diameter; adjusting means for adjusting the speed of said drive means and thereby the rotary speed of said spindle and the speed of said traveler and operation control means including a comparison device connected to said sensing means for receiving said signal, means for producing in said cornparison device a comparison signal in accordance with a program representing selected different tensions desired during different parts of the winding operation, said comparison device producing a command signal representing the diierence 'between said signals and thereby the deviation of the sensed actual tension from the desired tension selected in accordance with the program, said comparison device being connected to said adjusting means for actuating the same in accordance with said command signal so that the rotary speed of said spindle is varied during the winding operation in such a manner that the tension ofthe yarn between said bobbin and said device is maintained in accordance with the program at predetermined desired values while the diameter of said package increases during the winding operation.

19. Yarn tension adjusting apparatus for a draw-twisting machine comprising, in combination, a drawing-out device; a rotary spindle adapted to support a bobbin; a twisting ring surrounding said spindle, and a traveler mounted for movement along said twisting ring; a thread guide disclosed between said device and said spindle; a sensing means for sensing the tension of the yarn between said device and said thread guide, and adapted to produce a signal proportionate to the sensed tension; drive means operatively connected with said spindle for rotating the same so that the yarn supplied from said device through said thread guide and said traveler to said bobbin is wound up on said bobbin to form a package of gradually increasing diameter; adjusting means for adjusting the speed of said drive means and thereby the rotary speed of said spindle and the speed of said traveler; and operation control means for automatically actuating said adjusting means and including a comparison device connected to said sensing means for receiving said signal, and means for producing in said comparison device a control signal corresponding to a selected tension, said comparison device producing a differential signal supplied to said adjusting means whereby said actuating means adjusts the speed of said drive means in accordance with the differential signal so that the rotary speed of said spindle is varied during the winding operation in such a manner that the tension of the yarn between said thread guide and said device is maintained at predetermined desired values while the diameter of said package increases during the winding operation.

20. Yarn tension adjusting apparatus for a draw-twisting machine comprising, in combination, a drawing-out device; a rotary spindle adapted to support a bobbin; a twisting ring surrounding said spindle, and a traveler mounted for movement along said twisting ring; drive means operatively connected with said spindle for rotating the same so that the yarn supplied from said device through said traveler to said bobbin is wound up on said bobbin to form a package of gradually increasing diameter; adjusting means including an electric servomotor for adjusting the speed of said drive means and thereby the rotary speed of said spindle and the speed of said traveler; land operation control means including program controlled means adapted to produce a signal in accordance with a program and `operatively connected with said adjusting means for controlling the operation of said adjusting means depending on the program so IS that the rotary speed of said spindle is varied in such a manner that the tension of the yarn between said bobbin and said device is maintained at predetermined desired values while the diameter of said bobbin increases during the winding operation.

21. An apparatus as set forth in claim 20 wherein said electric servo-motor is directly connected with said program controlled means and effects adjustment of said drive means in accordance with said signal and program.

22. Yarn tension .adjusting apparatus for a draw-twisting machine comprising, in combination, a drawing-out device; a rotary spindle adapted to support a bobbin; a twisting ring surrounding said spindle, and a traveler mounted for movement along asid twisting ring; drive means operatively connected with said spindle for rotating the same so that the yarn supplied from said device through said traveler to said bobbin is wound up on said bobbin to form a package of gradually increasing diameter; adjusting means for adjusting the speed of said drive means and thereby the rotary speed of said spindle and the speed of said traveler, a tachometric means driven from said drive means and adapted to produce a control signal proportionate to the rotary speed of said spindle, a comparison device connected to said program controlled means and to said tachometric means receiving said signals and adapted to produce a command signal representing the difference between said signals and between a desired speed represented by said program and the actual speed of said spindle, said comparison device being connected with said adjusting means for controlling the operation of the same in accordance with said command signal.

23. Yarn tension adjusting apparatus for a draw-twisting machine comprising, in combination, a drawing-out device; a rotary spindle adapted to support a bobbin; a twisting ring surrounding said spindle, and a traveler mounted for movement along said twisting ring; drive means operatively connected with said spindle for rotating the same so that the yarn supplied from said device through said traveler to said bobbin is wound up on said bobbin to form a package of gradually increasing diameter; adjusting means including an electric servo-motor for adjusting the speed of said drive means and thereby the rotary speed of said spindle and the speed of said traveler; and operation control means including program controlled means adapted to produce a signal in accordance with a program, feed back means for producing a control signal proportionate to a physical variable representing an actual condition varying during a winding operation, a comparison device connected to said program controlled means and to said feed back means for receiving said signals and adapted to produce a command signal representing the dilerence between said signals and the deviation of the actual condition from a program represented condition, said comparison device being connected in the said adjusting means for controlling the operation of the same in accordance with said command signal so that the rotary speed of said spindle is varied in such a manner that the tension of the yarn between said bobbing and said device is maintained at predetermined desired values while the diameter of said bobbin increases during the winding operation.

24. Yarn tension adjusting apparatus for a draw-twisting machine comprising, in combination, a drawing-out device; a rotary spindle adapted to support a bobbin; a twisting ring surrounding said spindle, and a traveler mounted for movement along said twisting ring; drive means operatively connected with said spindle for rotating the same so that the yarn supplied from said device through said traveler to said bobbin Iis wound up on Vsaid bobbin to form a package of gradually increasing diameter; adjusting means including an electric servo-motor for adjusting the speed of said drive means and thereby the rotary speed of said spindle and the speed of said traveler; and operation control means including program controlled means adapted to produce a signal in accordance with a program, feed back means including a sensing means for producing a control signal proportionate to the yarn tension varying during a winding operation, a comparison device connected to said program controlled means and to said feed back means for receiving said signals and adapted to produce a command signal representing the diiference between said signals and the deviation of the actual yard tension and a program represented yarn tension, said comparison device being connected with said adjusting means for controlling the operation of the same in accordance with said commandsignal so that the rotary speed of said spindle is varied in such a manner that the tension of the yarn between said bobbin and said device is maintained at predetermined desired values while the diameter of said bobbin increases during the winding operation.

25. A yarn tension adjusting apparatus as set forth in claim 24 wherein said drive means include an electric motor, a gradually variable transmission means driven by said motor, a drive shaft driven from said transmission means, and other transmission means connecting said drive shaft with said rotary spindle; and wherein said adjusting means include means for varying the ratio of said variable transmission means, and a servo-motor for controlling said last-mentioned means and operatively connected to said comparison device and responsive to said command signal.

26. Yarn tension adjusting apparatus for a draw-twisting machine comprising, in combination, a drawing-out device; a rotary spindle adapted to support a bobbin; a twisting ring surrounding said spindle, and a traveler mounted for movement along said twisting ring; drive means including an electric motor operatively connected with said spindle for rotating the same so that the yarn supplied from said device through said traveler to said bobbin is wound up on said bobbin to form a package of gradually increasing diameter; adjusting means for adjusting the speed of said drive means and thereby the rotary speed of said spindle and the speed of said traveler, said adjusting means including means for stepwise varying the rotary speed of said electric motor, and an electric servo-motor connected to said last mentioned means for actuating the same whenever energized; and operation control means including a switch in the circuit of said servo-motor, rotary cam means, and driving means for driving said rotary cam means at a constant speed for actuating said switch to cause stepwise variation of the speed of said electric motor in accordance with a predetermined program represented by said rotary cam means so that the rotary speed of said spindle is varied during the winding operation in such a manner that the tension of the yarn between said bobbin and said device is maintained at predetermined desired values while the diameter of said package increases during the winding operation, said rotary cam means including a disk, and a plurality of cam lugs detachably mounted on said disk spaced selected distances from each other, each cam lug extending a selected distance in circumferential direction so that said switch is operated in accordance with a program represented by the spacing between said cam lugs, the number of said cam lugs, and the circumferential extension of each of said cam lugs.

27. In a draw twisting machine, in combination, a winding and twisting apparatus, comprising, rotatable spindle means adapted to support a bobbin; twisting means; a support mounting said twisting means for rotating movement around said spindle means; drive means for rotating at least one of said means so that yarn supplied to said twisting means is wound up on the bobbin to form a package of gradually increasing diameter; ad-v justing means for adjusting the rotary speed of said drive means and thereby the speed of said spindle means and of said twisting means; and actuating means including program controlled means adapted to produce signals in accordance with a program and a comparison device adapted to compare these signals with signals derived from said rotating means and being proportionate to the actual rotary speed of said spindle means so as to determine the relationship between said signals, said actuating means being connected to said adjusting means and controlling the same in accordance with variations of said relationship between sai-d signals-so that the rotary speed of said one driven means is varied in such a manner that the tension of the wound yarn is maintained at predetermined desired values while the diameter of said package on said bobbin increases during the winding operation.

28. In a draw twisting machine, in combination, a winding and twisting apparatus, comprising, rotatable spindle means adapted to support a bobbin; twisting means; a support mounting said twisting means for movement around said spindle means; drive means for rotating said spindle means so that yarn supplied to said twisting means is wound up on the bobbin to form a package of gradually increasing diameter; adjusting means for adjusting the rotary speed of said drive means and thereby the speed of said spindle means and of said twisting means; and actuating means including program controlled means adapted to produce signals in accordance with a program `and a comparison device adapted to compare these signals with signals derived from said rotating means and being proportionate to the actual rotary speed of said spindle means so as to determine the relationship between said signals,

said actuating means being connected to said adjusting means and controlling the same in accordance with variations of said relationship between said signals so that the rotary speed of said spindle means is varied in such a manner that the tension of the wound yarn is maintained at predetermined desired values While the diameter of said package on said bobbin increases during the winding operation.

29. In a draw twisting machine, in combination, a winding and twisting apparatus comprising, rotatable spindle means adapted to support a bobbin; twisting means; a support mounting said twisting means for movement around said spindle means; drive means for rotating one of said means so that yarn Supplied to said twisting means is wound up on the bobbin to form a package of gradually increasing diameter; adjusting means for adjusting the rotary speed of said drive means and thereby the speed of said spindle means and of said twisting means; and operation control means including program controlled means adapted to produce a signal in accordance with a program, feed back means for producing a control signal proportionate to a physical variable representing an actual condition varying during a winding operation, a comparison device connected to said program controlled means and to said feed back means for receiving said signals and adapted to produce a command signal representing the difference betweensaid signals and the deviation of the actual condition from a program represented condition, said comparison device being connected with said adjusting means for controlling the operation of the same in accordance with said command signal so that the rotary speed of said spindle is varied in such a manner that the tension of the yarn between said bobbin and said device is maintained at predetermined desired values while the diameter of said bobbin increases during the winding operation.

30, In a draw twisting machine, in combination, a winding and twisting apparatus, comprising, rotatable spindle means adapted to support a bobbin; twisting means; a support mounting said twisting means for movement around said spindle means; drive means for rotating one of said means so that yarn supplied to said twisting means is wound up on the bobbin to form a package of gradually increasing diameter; adjusting means for adjusting the rotary speed of said drive means and thereby the speed of said spindle means and of said twisting means; a tachometric means driven from said drive means and adapted to produce a control signal proportionate to the rotary speed of said spindle, a comparison device connected to said program controlled means and to said tachometric means receiving said signals and adapted to produce a command signal representing the difference between said signals and between a desired speed represented by said program and the actual speed of said spindle, said comparison device being connected with said adjusting means for controlling the operation of the same in accordance with said command signal so that the rotary speed of said one driven means is varied in such a manner that the tension of the wound yarn is maintained at pre determined desired values while the diameter of said package on said bobbin increases during the winding operation.

31. In a draw twisting machine, in combination, a winding and twisting apparatus, comprising, rotatable spindle means adapted to support a bobbin; twisting means; a support mounting said twisting means for movement around said spindle means; drive means for rotating one of said means so that yarn supplied to said twisting means is wound up on the bobbin to form a package of gradually increasing diameter; adjusting means for adjusting the rotary speed of said drive means and thereby the speed of said spindle means and of said twisting means; a sensing means for sensing the tension of the yarn between said device and Said bobbin, and adapted to produce a signal proportionate to the sensed tension; and operation control means including a comparison device connected to said sensing means for receiving said signal, means for producing in said comparison device a comparison signal corresponding to a selected tension, said comparison device producing a command signal representing the differ ence between said signals and thereby the deviation of the sensed actual tension from a desired selected tension and being connected to said adjusting means for actuating the same in accordance with said command signal so that the rotary speed of said one driven means is varied in such a manner that the tension of the wound yarn is maintained at predetermined desired values while the diameter of said package on said bobbin increases during the winding operation.

References Cited UNITED STATES PATENTS 1,412,518 4/1922 Guildford 57-93 2,682,144 6/1954 Hare 57-93 XR 2,735,257 2/1956 Legard et al. 57-93 2,785,527 3/1957 Lewellen et al. 57-93 2,885,898 5/1959 Malcolm et al. 57-93 XR 2,895,284 7/1959 Dritina 57-93 3,265,476 8/1966 Roberson 57-93 XR FOREIGN PATENTS 490,448 8/1938 Great Britain.

490,923 8/ 1938 Great Britain.

491,003 8/1938 Great Britain.

FRANK J. COHEN, Primary Examiner.

D. E. WATKINS, Assistant Examiner.

Claims

19. YARN TENSION ADJUSTING APPARATUS FOR A DRAW-TWISTING MACHINE COMPRISING, IN COMBINATION, A DRAWING-OUT DEVICE; A ROTARY SPINDLE ADAPTED TO SUPPORT A BOBBIN; A TWISTING RING SURROUNDING SAID SPINDLE, AND A TRAVELER MOUNTED FOR MOVEMENT ALONG SAID TWISTING RING; A THREAD GUIDE DISCLOSED BETWEEN SAID DEVICE AND SAID SPINDLE; A SENSING MEANS FOR SENSING THE TENSION OF THE YARN BETWEEN SAID DEVICE AND SAID THREAD GUIDE, AND ADAPTED TO PRODUCE A SIGNAL PROPORTIONATE TO THE SENSED TENSION; DRIVE MEANS OPERATIVELY CONNECTED WITH SAID SPINDLE FOR ROTATING THE SAME SO THAT THE YARN SUPPLIED FROM SAID DEVICE THROUGH SAID THREAD GUIDE AND SAID TRAVELER TO SAID BOBBIN IS WOUND UP ON SAID BOBBIN TO FORM A PACKAGE OF GRADUALLY INCREASING DIAMETER; ADJUSTING MEANS FOR ADJUSTING THE SPEED OF SAID DRIVE MEANS AND THEREBY THE ROTARY SPEED OF SAID SPINDLE AND THE SPEED OF SAID TRAVELER; AND OPERATION CONTROL MEANS FOR AUTOMATICALLY ACTUATING SAID ADJUSTING MEANS AND INCLUDING A COMPARISON DEVICE CONNECTED TO SAID SENSING MEANS FOR RECEIVING SAID SIGNAL, AND MEANS FOR PRODUCING IN SAID COMPARISON DEVICE A CONTROL SIGNAL CORRESPONDING TO A SELECTED TENSION, SAID COMPARSION DEVICE PRODUCING A DIFFERENTIAL SIGNAL SUPPLIED TO SAID ADJUSTING MEANS WHEREBY SAID ACTUATING MEANS ADJUST THE SPEED OF SAID DRIVE MEANS IN ACCORDANCE WITH THE DIFFERENTIAL SIGNAL SO THAT THE ROTARY SPEED OF SAID SPINDLE IS VARIED