US2936511A

US2936511A - Yarn clearing apparatus

Info

Publication number: US2936511A
Application number: US523245A
Authority: US
Inventors: Wilson Peter
Original assignee: William Hollins & Co Ltd
Current assignee: William Hollins & Co Ltd
Priority date: 1954-08-06
Filing date: 1955-07-20
Publication date: 1960-05-17
Anticipated expiration: 1977-05-17

Description

M y 17, 1960 P. WILSON 2,936,511

YARN CLEARING APPARATUS Filed July 20, 1955 3 Sheets-Sheet l 73 j ZO /2 3/ Q i /o l/ Inventor May 17, 1960 P. WILSON YARN CLEARING APPARATUS Filed July 20, 1955 3 Sheets-Sheet 2 Inventor Yawn? W/JLSU/V M y 17, 1960 1 WILSON 2,936,511

YARN CLEARING APPARATUS Filed July 20, 1955 3 Sheets-Sheet 3;

PETER 11/045017 United States Patent YARN CLEARING APPARATUS Peter Wilson, Nottingham, England, assignor to William Hollins & Company Limited, Nottingham, England Application July 20, 1955, Serial No. 523,245 Claims priority, application Great Britain August 6,1954

6 Claims. (Cl. 28-64) This invention is'for improvements in or relating to yarn clearing apparatus and is concerned with apparatus for detecting variations in the thickness of a running yarn. It will be appreciated that in the manufacture of fabric from textile yarn the variation in the thickness of the yarn is observable in the made upfabric. For the manufacture of high quality fabric, therefore it is essenial that the thickness of the required yarn shall be uniorm.

This invention is concerned with spun yarns which are composed of short fibres twisted togetherto form a continuous yarn and having a tendency to form slubs or enlargements which produce an undesirable appearance in a manufactured fabric. A slub may be defined as a defect in a spun yarn consisting of thick uneven places and its length is usually in the order of the length of the fibres forming the yarn.

Furthermore when a fabric is knitted from a yarn containing slubs or enlargements, these may cause damage or breakage of the needles resulting in. holes in the fabric.

In addition to apparatus for detecting slubs the invention is concerned with detecting other faults in the thickness of the yarn such as abnormally thin places in the yarn which wouldreduce the efiective strength of the Y It will also be appreciated that with spun yarns knots have to be formed between the successive lengths of the yarn to joint two lengths together and conveniently it is desirable that these short enlargements in the thickness of the yarn should not be detected by apparatus for detecting slubs or undue thinness of the yarn.

It has been proposed hitherto to detect slubs by passing the yarn between two parallel edges formed by hardened metal plates, the distance between the two edges of the plates being adjustable and arranged to permit the'passage of yarn of correct thickness but to oflfer obstruction to any slubs in the yarn. The aforesaid mechanical detecting devices are not wholly satisfactory in practice as certain types of faults, for example soft thick places which are easily flattened, may pass through the plates. In addition the yarn speed has to be limited in order to reduce mechanical damage to the yarn as it passes between the edges of the plate. Furthermore continual passage of a running yarn between two plates tends to wear grooves into one or both of the plates and these may cut or scrapethe yarn passing through them.

Other disadvantages are that the edges of the plates must be set parallel to each other; otherwise a tapered slotis formedvwhich enables thicker yarn to pass between the plates at one end of the slot than the other. If the yarn is being wound by being traversed along a cone the yarn may be drawn through the plates over a certain length of the slot so that certain slubs will be allowed to pass through the plates while others will be obstructed. The adjustment of the plates calls for a considerable degree of skill and the misalignment of the plates may be brought about by mechanical damage to the plates or by vibration of the winding machine. 7

It is an object of the present invention to provide im proved detecting apparatus of the kind herein referred to.

With the above and other objects in view the present invention provides apparatus for detecting: variations in thickness of a running yarn comprising a light sensitive device, a light source for directing a light ray onto said device, means for guiding a running yarn through the light ray, and indicating means actuated by said device consequent upon variations in the thickness of the yarn causing variations of the light intensity on said device and frequency responsive means to prevent actuation of the indicating means consequent upon the passage of either a nep or a knot in said yarn.

Conveniently the light sensitive device is some form of photo-electric responsive device and specifically may be in the form of a photo-electric cell. The indicating means may provide for severing of the yarn upon the light sensitive device responding to variations in the thickness of the yarn. The severing means may for example include a cutter plate mounted upon the armature of an electromagnetic relay. Other indicating means such as, for example, visual or audible indicating means or counting means may be provided, or alternatively the light sensitive device may be arranged to actuate means for stop ping the movement of the running yarn. Visual indicating means may conveniently be in the form of a counter for the number of slubs. The indicating means may also include an electronic tube operated by the light sensitive device which electronic tube may be of the gas filled type and normally biased to cut off. Conveniently the light sensitive device is arranged in the control electrode circuit of the said electronic tube so that variations in the light intensity falling on the light sensitive device due to variations in the thickness of the running yarn trigger the tube and render it conducting. The expression electronic tube as used herein defines a device which may be either of the thermionic type, i.e., provided with a heated cathode, of the cold cathode type and by which the flow of an electric current may be controlled. A tube for use with the present invention requires at least three electrodes which are hereinafter termed, cathode, trigger electrode, and anode. The fiow of electric current from the cathode to the anode is controlled by varying the potential of trigger electrode. An electro-magnetic relay may be provided inthe anode circuit of the tube which'relay is operated when the tube conducts.

More specifically the invention provides apparatus for detecting variations in the thickness of a running yarn comprising a photo-electric cell, a light source for directing a light ray onto said cell, means for guiding a running yarn through the light ray, a gas filled cold cathode tube having at least a trigger electrode, a cathode and an anode, normally biased to cut oil, and having the photoelectric cell in its trigger electrode circuit so that variations in the thickness of the yarn vary the light intensity falling on the cell and in consequence vary the trigger electrode potential of the tube to trigger it and render it conducting, and indicating means in the anode circuit of the tube operable upon the tube conducting and frequency responsive means to, prevent firing of said tube consequent upon the passage of either a nep or a knot in said yarn.

It will be appreciated it is often required to alter the sensitivity of apparatus according to the present invention in order to detect slubs of varying thickness. Furthermore it is desirable that the apparatus should not detect knots or neps which occur in spun yarns. A nep may be defined as .a small knot of entangled fibres whichin the case of cotton usually comprises dead or immature fibres and is considerably shorter in length relative to the yarn;

Patented May 17, 19,69-

than a slub. Means are therefore provided for adjusting the sensitivity of the apparatus. 7

It will be appreciated that when the thickness in the yarn varies it will cause a variation in the intensity of light which falls on the photo-electric cell which in turn will vary the output voltage of said cell. This variation in output voltage may be termed a pulse and according to the nature of the fault in the yarn the frequency components forming the pulse will vary (Fouriers analysis). Anep produces a pulse containing mainly very high frequency components, a slub on the other hand produces a pulse containing mainly medium frequency components due to the greater length relative to the yarn of the increased thickness in the yarn of a slub than a nep. A gradual variation in the thickness of the yarn as for example a gradual thickening of the yarn over a substantial part of its length will produce a pulse containing mainly very low frequency components. It is a feature of the present invention that frequency responsive means are provided for differentiating between the pulses containing very high frequency components produced by neps and knots and pulses containing very low frequency components produced by gradual variations in the thickness in the yarn and pulses containing medium frequency components as produced by a slub.

In the application of the present invention to a winding machine wherein there are provided a plurality of winding heads, apparatus according to the present invention may be provided associated with each winding head to detect slubs on each yarn being wound. It will be appreciated that the. sensitivity of each apparatus will vary due to variations in manufacture of the components of the said apparatus and in order to standardize the thickness of the slubs which are being detected each detecting apparatus has to be separately adjusted.

The invention also provides for an adjustment common to a plurality of detecting apparatus for altering the sensitivity in unison of the said plurality of detecting apparatus. Thus by an alteration of the common adjustment, the size'of slubs detected by the plurality of detecting apparatus each associated with one winding head may be varied to suit different yarns or to suit the different purposes for which the yearns are intended.

' The invention also provides a method of detecting defects in a running yarn which comprises passing the yarn through light focussed on to a photo-electric responsive device so as to interrupt part of said light and utilizing changes in actuation of the said device due to changes in the thickness of the yarn to actuate means to indicate said changes in the thickness of the yarn.

In order that the invention may be more readily understoodreference will now be made to. the accompanying drawings in which:

Figure 1 is a diagram of the electrimcircuit of one form of detecting apparatus according to the present invention,

Figure 2 is a side elevational view with parts being shown in cross section of a Winding location incorporating detecting apparatus according to the present invention,

Figure 3 is a side elevational view of detectingv apparatus according to the present invention,

Figure 4 is an end elevational view illustrating the apparatus of Figure 3 looking in the direction of the arrow A, and V Figure 5 is a diagram of an alternate electricvcircuit which can be employed in the present invention.

A running yarn is indicated at a audit is fed past a photo-electrical cell being guided through a gate between the cell 10 and a source of light indicated as a lamp bulb 11 provided with a focussing lens 8 and energized from

leads

12 and 13 connected toa low voltage supply. The yarn a is traversed past a slotted light aperture of greater width than the yarn so. that whileyarn sv P e en n. he e i ht a Pa t t e. ce l 10 on cold cathode gaseous discharge tube 16 having a trigger electrode 17 coupled through a condenser 1% to the cell end of resistance 14. The potential of the trigger electrode 17 is biased by means of a fixed resistance 19 and a potentiometer 20. The cathode of tube 16 is connected to lead 13 while the anode is connected by lead 21 through a switch 22 to one end of the coil of an electro-magnetic relay 23, the other end of which coil. is connected by lead 24 to supply lead 15. Connected in parallel with the switch 22 is a resistance capacity circuit comprising resistance 25 in series with condenser 26. The relay 23 has an armature 27 coupled by linkage 28 to a knife 2? arranged on the normal path of the yarn at a sufficient distance from the cell 10 to sever the yarn when a slub passes the cell before such slub has reached the knife.

In circuit with the resistance of the potentiometer 2%) is a normally closed jack switch 30 permitting a jack plug 31 when inserted to introduceinto the potentiometer circuit an adjustable resistance indicated at 32.

A suitable cell to employ as cell 10 is a PSOA germanium junction cell as sold by Standard Telephones & Cables Ltd. As the cold cathode tube 16 it is preferred to use a Gl/235G'tube as supplied by Standard Telephones & Cables Ltd. Thevalues of the resistance and capacities employed are conveniently as follows:

lay having a resistance of 20,000 ohms.

V In the operation of the apparatus yarn during its travel passes the gate of the cell 10 and partly but not completely shields the light from impinging thereon. During travel of the yarn if an enlargement occurs the change of thickness causes a sudden reduction of light impinging on the cell and the cell current is reducedcausing a fall in the voltage drop across resistance 14 thereby applying a voltage pulse to condenser 18 and trigger electrode 17. By a suitable choice of the values'of the components it is possible to ensure that only pulses which are produced by slubs or other faults of a predetermined size and shape provide a voltage pulse which when applied to the trigger electrode'17 raises the potential of that electrode sufliciently to cause the tube to fire. 7 Voltage pulses containing very low frequencies such as produced by a temperature. change or by' a gradual variation in the thickness of the yarn will be filtered off by the resistance capacity combination 19/18 and voltage pulses containing very high frequencies as result from the passage of a knot or nep will also sufier attenuation across resistance 14. When a voltage pulse as produced by a slub is applied to the trigger electrode 17, the tube fires and becomes conducting and completes the circuit of the relay 23 thereby actuating its armature and operating the knife 29 to cut the yarn. The relay 23 is self re-setting, its armature being coupled to switch 22 so as to open the latter on energization of the relay. When switch 22 is open the relay current continues to flow through condenser 26 and resistance 25 until the condenser is charged sutficiently to reduce the anode potential of tube 16 below the extinguishing value whereupon the tube then ceases to be conducting, thus de-energizing the coil of relay 23. On such de-energizationthecutter 29 is released and switch 22 is again closed, the potential of trigger electrode 17 having meanwhile fallen below the firing value so that the circuit again becomes quiescent until the arrival of the next slub inthe yarn.

Suitable yarn guides are conveniently provided to direct the yarn in the correct path past the photo-electric cell 10; these guides are conveniently of such a form as to facilitate threading the yarn in addition to ensuring its correct position.

The jack plug 31 and resistance 32 form a convenient means of setting the steady biasing voltage applied to the trigger 17 so that the tube 16 will respond only to pulses of a predetermined minimum amplitude. With the plug 31 and resistance 32 in circuit the potentiometer 20 is adjusted until self-triggering occurs. The plug 31 is then removed causing the required biasing voltage to be applied through omission of the resistance 32 from the circuit. The resistance 32 may be adjusted in value to determine precisely whatever steady biasing voltage is required to be applied to the trigger 17 to suit particular conditions, including for example the thickness of the yarn in use.

In Figure 2 a yarn a is being wound from a cop 41 on to a cone 49. The cop is supported on a cop holder 42 secured to a frame 40 of the winding machine. The yarn a passes through a yarn tensioning device comprised by a lower friction disc 44 and an upper friction disc 45 loosely centred on a vertical shaft 43. The tension is applied by the weight of the upper disc 45 augmented if necessary by metal washers placed on the upper disc 45. The yarn then passes through a box 34 containing slub detecting apparatus, under a hooked drop wire 46, over a roller 47 rotating in a trough 48 containing water or sizing liquid and on to the cone 49. The box 34 is provided with, yarn guides 33 and 37 having enlarged friction reducing bushings35 and 38 provided atthe centre and forming an aperture 36 through which the yarn may pass. An electric light bulb 11 is mounted below the running yarn and is arranged to project a light ray on to a lightjsensitive device in the form of a photoelectric cell 10. An electro-magnetic relay 23 having an armature 27 is provided with a cutting knife 39 on the armature and arranged below the running yarn so that actuation of the relay and consequent movement of the armature 27 results in the cutter 39 being brought into contact with the yarn and severing the yarn.

The electric circuit illustrated in Figure operates in the following manner: A cold cathode gas filled tube T is normally biased to cut 01f so as to be non-conducting. A potential is applied to the trigger electrode of the tube via resistance R2 by means of potentiometer R3. The light ray from the lamp is focussed onto the photoelectric cell so as normally to-maintain the tube nonconducting. In the event of the light ray being inter rupted and the current of the photo-electric cell falling the trigger electrode of the tube T will become more positive by means of the bias applied through condenser C1 and the tube will be triggered and will conduct. A current will flow through the tube T, resistance R4, the switch and contact A2, and the relay 23 to the positive potential V1. As soon as the tube conducts the relay 23 is actuated and the switch begins moving toward the contact A1. While the switch is moving the relay is maintained operated by the tube continuing to conduct and charging the condenser C2. Once the switch has moved so as to maintain a conducting path from potential V1 through relay 23, condenser C2 and resistance R4 to ground, the tube immediately becomes non-conducting as insufiicient positive potential is applied to the anode but the relay 23 is still held on due to the condenser C2 continuing to charge. As soon as the con denser C2 is charged or nearly charged the current flowing through relay 23 falls and the relay 23 is deenergized returning the switch from the contact A1 to the contact A2 in the position illustrated in Figure 5 and the circuit is again at rest. The sensitivity of the circuit may be altered by variation" of the bias applied to the trigger electrode of tube T which may be adjusted by the potentiometer R3. The frequency responsive means consists of the condensers C1 and R2 acting as a resistance capacity, time constant circuit to smooth out the low frequency components of the pulses and the condenser C3 to smooth out high frequency components of pulses. The condenser C3 acts as a high frequency smoothing circuit to prevent triggering of the tube T consequent upon high frequency variations of the potential across resistance R1. Only a prolonged variation of the potential across resistance R1 triggers the tube so that alterations inthe current of the photo-electric cell consequent upon short variations in yarn thickness such as for example knots or neps will not be detected by the apparatus. By a suitable choice of condenser C3 knots or neps will pass undetected and slubs of substantial length in comparison with knots or neps will be detected. The tube is conveniently provided with an additional electrode whose purpose is to illuminate the main gap between the cathode and the anode of the tube so as to ensure a supply of ions to facilitate rapid breakdown of the internal resistance of the tube when the tube is triggered. This electrode is connected to ground through resistance R5.

The values of the components illustrated in Figure 5 are as follows:

Relay 23 manufactured by Magnetic Devices Ltd. Type 595.

Light sensitive device 10, Standard Telephones & Cables Ltd.

Photo-cell PSOA.

T Ericsson Telephones Limited. Tube GTE M.

R1-220,000 ohms.

R2--l',000,000 ohms.

R31,000,000 ohms.

R44,700 ohms.

R510,000,000 ohms.

C1--0.l microfarad.

C2-8 microfarad.

C3-0.001 microfa rad.

V1-280 volts D.C.

V2-1 10 volts D.C.

V3- 4 to +4 volts D.C.

V48 volts A.C.

A plurality of detecting apparatus according to the present invention may be applied to a winding machine having a plurality of winding heads such that one detecting apparatus is provided for each winding head and each detecting apparatus may be separately adjusted to provide the same sensitivity for detecting slubs of the same minimum size and permitting the passage of knots or neps of the same maximum size. The initial adjustment of sensitivity of each detecting apparatus is provided by alteration of the potentiometer R3. If it is desired to alter the sensitivity of all the detecting apparatus common to a winding machine the difierence in potential between V1 and V3 may be adjusted by a potentiometer common to all the detecting apparatus on a winding machine. Thus if it is desired to wind yarn for one purpose and to detect slubs of minute size the potential between V1 and V3 is reduced so as to reduce the cut-off bias and increase the sensitivity of each detecting apparatus. If it is desired to wind yarn in which a larger size of slub is permitted then the potential between V1 and V3 is adjusted to increase the cut-off bias and to reduce the sensitivity of the detecting apparatus.

In order to standardize the sensitivity of each detecting apparatus a standard testing device may be provided in the form of a wire of known thickness which is mounted in a sprung jack so that it can be rapidly moved between the light source 11 and the photo-electric cell triggered when the standard wire is passed through the light beam at a pre determined speed.

It will be appreciated that the present invention pro vides a slub. yarn thickness detecting apparatus in which substantially no tension is applied to the yarn in order to detect variations in the thickness of the yarn. The only tension applied to the yarn is due to the friction of the

yarnguide bushings

35 and 38 and/or of the discs 44 and 45.

The invention also enables the sensitivity of the detecting apparatus to be adjusted according to the requirements of the yarn and such adjustment may be made common to a plurality of detecting apparatus on a winding machine thus obviating the necessity of adjusting each detecting apparatus separately. Furthermore the invention enables each detecting apparatus to be adjusted accurately to determine substantially the same variations in thickness of yarn thus ensuring uniformity in the detection of sluhs or the permitted tolerance of knots and neps.

Various changes and modifications may be made without departing from the spirit and scope of the present invention and it is intended that such obvious changes and modifications be embraced by the annexed claims.

Having thus described the invention, What is claimed as new and desired to be secured by Letters Patent is:

1. An apparatus for detecting variations in running yarn comprising a single photo-electric'cell, a light source, a' lens disposed between said cell and said light source for focusing light rays from said light source on said cell, means for guiding a running yarn between said lens and said cell, a single electronic tube provided with an anode, a cathode, and a trigger electrode, a source of biasing voltage for said trigger electrode, means connected to said trigger electrode for adjusting the initial biasing voltage from said source of biasing voltage, said cell being connected in circuit with said trigger electrode so that variations in the thickness of said yarn vary the signal voltage from said cell and applied on said trigger electrode, indicating means connected to said tube and operable when the total of said biasing voltage and said signal voltage permit said tube to fire, and means to prevent firing of said tube and actuation of said indicating means upon passage of anything other than a slub.

2. Apparatus for detecting variations in the thickness of a running yarn, comprising a single photo-electric responsive device, a light source, means. for directing: a light ray from said source onto, said device, rnean s for guiding a running yarn through the light ray, a single electronic tube having at least a cathode, an anode and a. trigger electrode normally biased to cut-off so. that normally there is no anode current, said photo-electric responsive device being connected in circuit with said trigger electrode, whereby variations in the thickness of said yarn vary the intensity of light falling on said device and in consequence thereof vary the electric current from said device and thus varies the biasing voltage on said trigger electrode to thereby trigger said tube and render it conducting when said electric current is below a pre determined limit, indicating means operable by said tube becoming conducting, and means connected in circuit with said photo-electric responsive device and said trigger electrode to prevent triggering of saidtube and actuation of said indicating means, consequent upon the passage of either a nep or'a knot in the yarn through said light ray;

3. Apparatus according to claim 2, said indicating means comprising an electro-magnetic relay, and a cutter for cutting the yarn operable by said electro-magnetic re ay. 7 a

4. Apparatus according to claim 2, further-comprise ing means for adjusting the initial biasing voltage on said tr gger electrode, thereby to vary therange of variations in thickness of the yarn which are detected.-

5. Apparatus according to claim 2, further comprisirrg means for adjusting the biasing voltage on said trigger electrode and including a potentiometer to thereby vary the range ofvariations in thickness of yarn which are detected.

6. Apparatus according to claim 2, wherein said last recited means comprises a condenser for smoothing .out the high frequency components of-a pulse produced by either a nep or a knot in said yarn.

References Cited in the file of this patent Ingham Aug. 28, 1951