US3220758A

US3220758A - Yarn knotting device and control means

Info

Publication number: US3220758A
Application number: US307077A
Authority: US
Inventors: Raasch Hans; Gith Walter
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-09-07
Filing date: 1963-09-06
Publication date: 1965-11-30
Anticipated expiration: 1982-11-30
Also published as: GB1067457A; GB1067456A; CH437854A; BE637017A; CH427691A; DE1247914B

Description

Nov. 30, 1965 H. RAASCH ETAL YARN KNOTTING DEVICE AND CONTROL MEANS 5 Sheets-Sheet 1 Filed Sept. 6, 1963 FIG? Nov. 30, 1965 H. RAASCH ETAL 3,220,753

YARN KNOTTING DEVICE AND CONTROL MEANS Filed Sept. 6, 1963 5 Sheets-Sheet 2 //IIIIIIII{I7IIIIIIIIIIII W l h Nov. 30, 1965 H. RAASCH ETAL 3,220,758

YARN KNOTTING DEVICE AND CONTROL MEANS Filed Sept. 6. 1963 5 Sheets-Sheet 3 Nov. 30, 1965 H. RAASCH ETAL YARN KNOTTING DEVICE AND CONTROL MEANS 5 Sheets-Sheet 4 Filed Sept. 6, 1963 Nov. 30, 1965 H. RAASCH ETAL 3,220,758

YARN KNOTTING DEVICE AND CONTROL MEANS Filed Sept. 6, 1963 5 Sheets-Sheet 5 United States Patent 3,220,758 YARN KNOTTING DEVICE AND CONTROL MEANS Hans Raasch, Rheydt-Odenkirchen, and Walter Gith, Monchen-Gladbach, Germany, assignors to Walter Reincrs, Monchen-Gladbach, Germany Filed Sept. 6, 1963, Ser. No. 307,077 Claims priority, application Germany, Sept. 7, 1962, R 33,460 14 Claims. (Cl. 289-18) Our invention relates to yarn knotting devices for use in textile manufacture and to control or monitoring means therefor, to actuate a signal or to block operation of the knotter if there has been placed therein more than the proper number of strands of yarn, or upon departure of the thread number or dimension from a predetermined value.

It is known to connect two yarn ends by means of a manual knotting device equipped with means which permits the knot-forming operation to take place only if the two yarn ends to be tied together are properly located in the device. If only one end is placed into the knotter, or if the two yarn ends are improperly placed into the knotter, the operation remains blocked so that no faulty knot can be brought about.

Our invention, in a more particular aspect, also relates to a knotting device equipped with a supervisory device that checks the proper presence of the two yarn ends to be knotted together. However, the invention is not limited to manual devices but is particularly advantageous in the form of an automatic knotting device, for example as a component in automatic yarn-package winding machines or other textile fabricating machinery. Automatic yarn knotters for tying a fishermans knot are known, for example, from US. Patent No. 2,981,559 of S. Furst, and from application Serial No. 159,197 of Gregor Gebald et al., filed May 17, 1961, now Patent No. 3,110,511, issued November 12, 1963. Automatic knotters of this type can be used in automatic winding machines of the multi-station type described, for example, in US. Patcnts 3030,040 of W. Reiners, issued April 17, 1962; 3,033,478 of S. Furst, issued May 8, 1962;

3.035.783 of S. Fttrst, issued May 22, 1962;

3,057,577 of M. Ruhl, issued October 9, 1962; 3,06l.2l6 of S. Furst et al., issued October 30, 1962; 3.067.962 of S. Furst et al., issued December 11, 1962; 3.0773 ll of S. Furst, issued February 12, 1963; 3.077312 of S. Furst, issued February 12, 1963; 3.078.054 of S. Furst, issued February 19, 1963; and 3,092,340 of S. Furst, issued June 4, 1963.

It is one of the objects of our invention to devise a kno-itcr whose supervisory equipment responds not only to proper presence of the two yarn ends to be tied together but which also prevents the knotter from operating if more than two yarn ends are simultaneously placed into the knotter.

To this end, and in accordance with a feature of our invention. we provide the knotting device with a supervisory measuring device which is responsive to the number of yarn ends simultaneously passing into the knotter and which for this purpose comprises yarn-responsive sensing means near the yarn path at the knotter, and aiso signal receiving output means, such as an indicating signal device, a relay or the like, the signal-receiving means being actuated when only one yarn end or more than two yarn ends pass into the knotter. The foregoing object and feature of our invention will be more fully explained in the following.

Another object of the invention is to provide a device which will always secure proper knotting of no more ice than two individual yarn ends coming respectively from the supply coil and take-up spool of a yarn winding machine.

Heretofore, if only one yarn end is placed into a knotter, for example in an automatic yarn-package winding machine, and if no provision is made to then prevent the knotting operation, the knotter will operate but the result will be faulty and the yarn end is not tied together with another yarn end, so that the faulty operation has no disadvantage other than loss of time. Moreover, if more than two yarn ends are placed into such a knotter, all of these yarn ends become tied together so that double or triple threads enter into the subsequent fabricating operation.

In automatic winding machines in which a yarn end coming from below, namely from a supply coil, and a yarn end coming from above, namely from the take-up spool, are automatically knotted to each other, the upper yarn end and the lower end, as a rule, are seized by respective gripper members and are then conveyed thereby into the knotter where they are placed in overlapping relation to each other before the knot-forming elements or tie beaks of the knotter commence operating. Under particularly unfavorable conditions it may then happen that a yarn end is caught at the supply coil or take-up spool or at another machine part with the result that the gripper, when passing the yarn to the knotter, will pull and entrain a loop of yarn. In this manner, the upper yarn end or the lower end enters into the knotter in form of a double thread. When now the knotter operates, it ties the double thread together with the other yarn end, and during the subsequent winding operation of the machine, the knot containing double thread is wound into the yarn package being built up.

Another possibility of how a double thread can become placed into the knotter may occur when a supply coil is depleted and exchanged for a full coil. It may then happen occasionally that, for example on account of faulty coil cores, two new coils are inserted instead of one; and the gripper will then convey two lower yarn ends instead of one into the knotter. As a result, the two lower yarn ends become tied together with the single yarn end of the take-up spool, so that a double thread may extend over a great length and be wound into the yarn package.

There are automatic yarn-package winding machines which do not have a built-in knotter at each individual winding station but in each machine a single knotter services a large number of winding stations. In such multi-station machines the knotter travels past the winding stations (for example, according to US. Patents 3,033,478 of S. Furst, issued May 8, 1962; 3,077,311 of S. Furst, issued February 12, 1963; 3,078,054 of S. Furst, issued February 19, 1963),

or the winding stations travel past a stationarily installed knotter (for example, according to US. Patent 3,030,040 of W. Reiners, issued April 17, 1962). It may happen that the lower yarn end is properly placed into the knotter, whereas the upper yarn end is missing. Although in this case no knot is formed, the lower yarn end may remain caught in the knotter. When the knotter then travels to the next winding station at which a tying operation is to be performed, the caught yarn end from the precedingly serviced station is dragged along by the knotter travel and forms a so-called dragging thread. The dragging thread is apt to be caught by the yarn running onto the take-up spool in another winding station, thus also resulting in winding a double-yarn into the yarn package of that other station. Regardless in which particular manner a double thread may have entered into the knotter, a double length of yarn wound into a yarn package does not cause the yarn guard or other sensing devices of the winding machine or of the subsequent textile fabricating machines to respond, so that such faults are carried along into the finished fabric product. Although it has been found that even under particularly unfavorable conditions the occurrence of double yarn faults will occur only at about 3 per mil of the total number of knotting operations, it is desirable to prevent such defects because, when they occur, the quality of the product may be greatly impaired.

It is therefore a more specific object of my invention to minimize, virtually down to complete elimination, the possibility of having a yarn knotter operate with more than the two yarn ends properly required.

By virtue of the fact that according to the invention the supervisory device combined with the knotter measures the number of the yarn ends passing into the knotter, the above-mentioned defects can indeed be obviated with reliability.

Another object of the invention is to provide a supervisory device which, when responding to the presence of more than the proper number of yarn ends or strands, serves to actuate a signal in order to call attention of the attending personnel to the occurrence of the defect.

A further object of the invention is to provide a supervisory device which, when responding to more than two yarn ends being present in the knotter, releases a blocking device that prevents the further fabrication of the yarn. Such a blocking device, in a yarn-package winding machine, may be designed according to the invention, to block the winding operation, or may prevent the knotter from performing the knotting operation, or may cut or tear the yarn, or may clamp the yarn or cause it to be eliminated from the knotter before the knotting operation is performed.

The yarn-responsive sensing means of the device for checking the proper number of yarn ends passing into the knotter are preferably of the proximity type so that the yarn movement is not impeded by mechanical contact with the sensing means. The measuring device may determine the number of yarn ends received in the knotter by measuring or responding to the volume or diameter or overall dimension of the yarn quantity passing by the sensing means, or the measuring device may also operate by pulse counting. For many purposes a measuring device has been found preferable that operates on the principle of a capacitance or dielectrical measurement. Such a device responds substantially to the volume of the amount of yarn material passing by a capacitive probe and causing a change in the dielectric constant of that probe, this change being measured in an electric circuit or bridge network as generally known for capacitance or dielectric measurements.

The above-mentioned and more specific objects and features of our invention, said features being set forth with particularity in the claims annexed hereto, will be apparent from and will be further described in the following with reference to the embodiments of apparatus according to the invention illustrated by way of example on the accompanying drawings in which similar parts and elements are designated by like reference numerals throughout the several views, and in which:

FIGS. 1 and 2 each show a front view of a knotter according to the invention receiving two yarn ends, FIG. 1 relating to an initial stage of operation and FIG. 2 to a stage shortly prior to completion of a knot.

FIG. 3 is a side view in cross section of a knotter according to FIGS. 1 and 2.

FIG. 4 is a cross-sectional view of a multi-station winding machine having a travelling servicing unit equipped with a knotter and supervisory equipment according to the invention.

FIG. 5 shows schematically a yarn severing device which forms part of the supervisory equipment of the 4 knotter and also part of the servicing unit according to FIG. 4.

FIG. 6 is a schematic circuit diagram of the knotter supervisory equipment in the apparatus according to FIGS. 1 to 5.

FIG. 7 is an explanatory diagram relating to the operation of apparatus according to the invention, illustrating a cross sectional view through two adjacent yarn ends or strands.

FIG. 8 shows schematically an embodiment of photoelectric sensing means together with an apertaining circuit diagram for use in knotter supervisory apparatus otherwise similar to that of FIGS. 1 to 5.

FIG. 9 is a schematic circuit diagram of another embodiment of a photoelectric type of sensing means.

FIG. 10 is a modification of the device of FIG. 8, and

FIG. 11 is a fragmentary side view in section of the drive means of FIG. 10.

The knotter shown in FIGS. 1, 2 and 3 is generally of the known type designed for producing a fishermans knot. Such knotters are more fully described in the above-mentioned US. Patent 2,981,559 of S. Furst; also in application Serial No. 159,197 of Gebald et al., now Patent No. 3,110,511 and in copending application Serial No. 306,265, of Albert Pesch, filed September 3, 1963.

The sensing means of the supervisory measuring device with which the illustrated knotter is equipped according to the present invention are constituted by two capacitors 1 and 2 which are fastened to the housing structure 101 of the knotter. Thus mounting the sensing capacitors 1 and 2 directly on or at the knotter, and in the immediate vicinity of the yarn path constituted by the diametrically opposite slots 1a and 2a (FIG. 2) into which the two yarn ends 3 and 4 are to be inserted, has the advantage that the number of yarn ends or strands is measured in the immediate vicinity of the knotter itself, i.e. the beaks 5, 6 and hence very close to the knot to be formed. However if it is desirable to ascertain the number of mutually adjacent yarn ends at a different location of the yarn path, a correspondingly designed measuring or sensing device 1, 2 may conveniently be located at such other location.

In the illustrated embodiment of FIGS. 1 and 2, the right-hand yarn 3 coming from below, namely from the supply coil (10 in FIG. 4) by-passes the lower capacitor 2 and is inserted into the slot 1a which forms part of the upper sensing capacitor 1. The upper yarn end 4 located at the left and coming from the take-up spool (11 in FIG. 3) by-passes the upper capacitor 1 and is inserted into the knotter so as to pass through slot 2a of the lower sensing capacitor 2. As will be more fully described with reference to FIG. 6, the two capacitors 1 and 2 are connected in a bridge network and are energized from an oscillator by high-frequency current. If only one yarn end passes through each of the respective sensing capacitors, the same change in impedance takes place at both capacitors so that the bridge network remains in equilibrium. However, if no yarn passes through one of the two capacitors l, 2, or if two yarn ends are placed through one of the capacitors, the bridge balance is disturbed so that a voltage appears between the two normally equipotential diagonal points of the bridge network. This output voltage, amplified, if necessary, is used for actuating a signalling device, such as a lamp, or a yarn severing device 19, further described below. It is preferably to have the supervisory measuring device electrically switched on only at the time when the two yarn ends 3, 4 are placed, or supposed to be placed, into the knotter. This can be done by the means and in the manner described below with reference to FIG. 4.

The mounting of the sensing means 1, 2 directly at the knotter has the following further advantage. As is more fully described in the above-mentioned Patent 2,931,559, each of the two tie beaks 5 and 6 of the knotter is provided with a cutter or cutting edge which, after the knot is formed and tightened, cuts the superfluous free ends off the knotted yarn. By having the apparatus according to the present invention perform another measuring operation, it can be ascertained whether the tie beaks 5 and 6, after tightening of the knot, have properly eliminated the surplus loose ends. A faulty cutting operation of a tie beak 5, 6 may likewise result in double threads because a yarn end dangling from a knot is likewise wound into the yarn package; and such occurrences can likewise be prevented by virtue of the present invention.

FIG. 1 shows a front view of the knotter in the initial stage of operation at a moment in which the respective gripper devices 16, 17 (FIG. 4) have just conveyed the lower yarn end 3 and the upper yarn end 4 into the knotter. Thereafter the tie beaks 5 and 6 are rotated about their respective axes to form respective component knots, and the appertaining cutting edges of beaks 5, 6 then act to eliminate the residual dangling ends away from the knots.

The principle involved in tying a fishermans knot of this type is further described in the above-mentioned Patent No. 2,985,599 of S. Furst, and in application Serial No. 159,197 of Gregor Gebald et al., filed May 17, 1961, now Patent No. 3,110,511, issued November 12, 1963. In a knot of this type, each of the two yarn ends to be tied together is first given a simple individual knot through whose loop the other yarn end can glide. Since each yarn end has its own knot, the two knots can move toward each other during tightening of the loops until they touch each other and then prevent each other from gliding out of the loop of the adjacent yarn end. The two tie beaks 5, 6 serve to tension the yarn ends after the individual knots are formed. Thereafter the tie beaks loosen and release the respective yarn ends. Such release takes place after the individual knots are formed but before they are tightened together. The knotter is provided with a tensioning member or tappet 7 which moves on a straight line between the two tie beaks 5, 6. The member 7 acts upon the yarn portions located between the tightened individual knots and tests the knotted tie.

FIG. 2 shows the knotter after the tie beaks 5 and 6 have thus operated and have eliminated the free ends. Thereafter the tensioning member or tappet 7, moving toward the observer in the view on FIG. 2, tautens the yarn and thereby pulls the components together, thus forming a single and tight fishermans knot. When the knotter has reached the stage shown in FIG. 2 and has properly performed the operations described, no yarn must remain in the two sensing capacitors 1 and 2. Consequently, the above-mentioned measuring bridge, when performing another measuring operation, is now again in equilibrium and does not furnish an output voltage. However, if one of the dangling yarn ends is not cut off, one of the two sensing capacitors 1, 2 would have a different impedance than the other so that the measuring bridge would furnish an output voltage applicable for indicating the fault or performing any desired preventive operation.

It is conceivable that in both operating stages according to FIGS. 1 and 2 a double thread might simultaneously be received in both sensing capacitors 1 and 2 or that both tie beaks might simultaneously fail to perform the desired cutting operation. In the event of such a coincidence, the measuring device would not respond. As mentioned, however, a double thread occurs statistically only in about three per mil of all knotting operations. The probability then that two double threads might simultaneously be received in the knotter is thus virtually nil. The same applies to the case that both tie beaks might not cut the respective yarn ends simultaneously. At the knottcrs nowadays employed, the scissors or cutters provided on the beaks 5, 6, used for cutting the residual ends can perform several millions of cuts without impairment of the cutting ability. It is therefore likewise extremely improbable that both tic beaks 5, 6 will simultaneously fail to properly operate.

The knot-tying operation of the knotter 15 of FIG. 3 and its tensioning member 7 is in general accordance with that more fully described in the above-mentioned Patent 2,981,559.

The yarn-package winding machine shown in FIG. 4 is generally in accordance with those more fully described in the afore-mentioned US. Patents 3,078,054 and 3,077,311. The yarn F, corresponding to the yarn 3 of FIGS. 1-3, and coming from a supply coil 10 at a respective winding station, passes through a yarn tensioner 18 and thence over a yarn guiding drum 112 onto the take-up spool 11. The normal path of yarn F from the tensioner to the take-up spool 11 is indicated by a dotand-dash line. (The respective yarn portions 3, 4 form part of the yarn F after the knot is tied and the winding operation again proceeds.) Of course it is assumed that at the illustrated moment of FIG. 4 the supply coil previously in the dot-and-dash position at 10 has become depleted and doffed and is about to be substituted by a new supply coil 10, so that at the illustrated moment no yarn end 3 is in reality yet available from the new supply coil 10. The servicing unit or tender 14 runs on horizontal rails 12 and 13 along a plurality of winding stations in a direction perpendicular to the plane of FIG. 4 and carries the knotter 15. If the supply coil 1!) is in the proper position at 10 and during the winding operation, the yarn F coming from this coil becomes broken, yarn guard 117 responds to absence of yarn, causing a gripper member 16 to seize the yarn end 3 at a point along the path F between the supply coil 10 and the tensioner 18. At the same time, the yarn end 4 from the take-up spool 11 is seized by a gripper 17. Both grippers 16, 17 are pivotally mounted on the travelling servicing unit 14, and after thus seizing the respective yarn ends, move about their respective pivots and thereby place the yarn ends 3, 4 into the knotter 15 where they then occupy the positions shown in H6. 1.

Mounted on the travelling unit 14 between the yarn tensioner 18 and the knotter 15 is a scissorstype cutter 19 (FIGS. 4, 5). The cutter 19 is mounted along the path F, preferably as close to the knotter 15 as the particular machine design will conveniently permit. The actuation of the cutter 19 is released by the supervisory measuring device, for example according to FIG. 6, under control by the yarn-responsive sensing means which in the illustrated embodiment are constituted by the capacitors 1 and 2 (FIGS. 1, 2, 3) when the above-mentioned equilibrium of the bridge network is disturbed during the measuring operation.

The control of the cutter 19 is efTect-ed according to FIG. 5 by an electromagnet or solenoid 20 (FIGS. 5, 6) which is energized from the bridge network in depend-- ence upon occurrence of bridge unbalance, preferably through an amplifier as shown at 27 in FIG. 6. As long as the magnet 20 is not energized, a movable leg 19/) of the cutter 19 is kept in open condition by a spring 19:: (FIG. 5.) The armature 20a of the magnet is normally held in lifted position by a spring 20/). As soon as the magnet 20 is energized, the armature 20a is pulled into the magnet in opposition to the force of spring 20/) so that the lower end 200 of the armature strikes against the pivoted leg 19!) of the cutter l9 and closes its cutting scissors, thus severing the yarn end 3 along its path between the tensioner 18 and the knotter 15 (FIG. 4) in the event only one yarn end or more than two yarn ends are received by the knotter.

As mentioned, it is generally of advantage to have the measuring device of FIG. 6 normally switched off and to render it electrically operative, by means if a switch 22, only when the yarn ends are placed into the knotter or additionally immediately after completion of the knotting operation. The first measuring or checking operation then serves to determine whether the correct number of yarn ends is received in the knotter 15, whereas the subsequent measuring operation determines whether the residual ends are properly cut off by the cutting edges of the tie beaks 5, 6 upon tightening of the knot. For securing the performance just described, the device is provided with a cam disc 21 (FIG. 4) which forms part of the tender 14 and cooperates through a cam follower 136 with a switch 22 (FIGS. 4, 6) to switch the measuring device on and off at the proper stages of operation. The cam disc 21 is fastened on the cam shaft 23 which controls the operation of the knotter in the manner known from the above-mentioned Patents 3,077,311 and 3,078,054. As a result, the proper synchronization of the knotter performance relative to the temporary or intermittent performance of the supervisory measuring device is secured.

schematically shown in the circuit diagram of the measuring device according to FIG. 6 are the two sensing capacitors 1 and 2 at a stage of operation, corresponding to FIG. 1, in which respective yarn ends 4 and 3 are received. The two capacitors 1 and 2 are connected in two branches of a bridge network whose other two branches are constituted by

resistors

28 and 29 of which at least one, as shown at 28, is preferably adjustable for calibrating purposes to serve as discriminating means. The input diagonal of the bridge is energized from an oscillator or high-frequency generator 26 which receives current through a current supply unit 25, preferably connected to a utility outlet furnishing alternating current, for example of 110 volt and 50 or 60 eps. The bridge network is normally balanced by corresponding adjustment of the variable resistor 28. If the bridge balance becomes disturbed, for example by absence of the upper yarn end 4 or by the presence of more than one lower yarn end 3, then an output voltage occurs at the diagonal points A and B of the bridge network, which voltage is amplified by an amplifier 27 and applied to the abovedescribed magnet for actuation of the cutter 19 to sever the yarn F. Such operation takes place only when the switch 22 is closed, and this takes place under control by the above-mentioned cam 21 (FIG. 4).

Operation of the device of FIGS. 1-6 is as follows.

If the supervisory or monitoring device of FIG. 6 has responded because of a doubled lower yarn end 3, then, according to this embodiment of the invention, this doubled yarn end will be knotted together with the upper yarn end 4 and then run onto the take-up spool 11; but after completion of the faulty knot, no further yarn will pass onto the take-up spool because the lower yarn end will have been severed by scissors 19 (FIGS. 4, 5) shortly behind the knot by the automatic operation of the supervisory device of FIG. 6. Consequently, the winding station will now behave as if a yarn break had occurred. Peeler member 117 will respond to absence of yarn along path F and the knotter will thus be caused to commence another knotting operation. Consequently, the gripper 17 for the upper yarn end 4 will pull the yarn otf take-up spool 11 downwardly until the defective length of yarn with the faulty knot is well below and no longer placed into the knotter. After the second knotting operation is then completed, the severing devices of the knotter beaks 5, 6 cut the faulty knot off the yarn so that it is eliminated as waste from the machine. However, if the supervisory device has ascertained that the upper yarn end 4 is missing, the lower yarn end is likewise cut off and the loose yarn residue still dangling from the knotter is now eliminated, for example by means of a suction nozzle. A waste yarn discharge device of this latter type is described in the above-mentioned copending application Serial No. 306,265 of Albert Pesch.

It has been found that the above-described capacitive sensing device for determining the number of yarn ends received in the knotter, though reliable for most kinds of yarn, may not be sufficient in some exceptional cases. With certain kinds of yarn it may happen that for one and the same yarn count, the cross section of the yarn may vary. Comprehensive measurements on textile threads have shown that the smallest to largest cross sections of a given yarn count may vary over short yarn lengths in the ratio of 112, whereas these variations substantially equalize themselves over extended lengths of yarn. Consequently, in a completely stationary type of measurement a thicker yarn locality of one and the same yarn may possess approximately the same cross section as two thin localities together. Thus two thin yarn localities together in the capacitor 1 or 2 may not be sensed by the bridge network. To overcome this difficulty, it is of advantage to apply the measurement or checking to a relatively long length of yarn, for example 200 mm., and if necessary, to use an integrating circuit or amplifier so that the operation of the measuring device depends upon the average value measured. This is achieved by giving the above'described capacitors 1 and 2 a correspondingly long length in the yarn-path direction, or by designing cam 21 to close switch 22 so as 'to perform the measurement during an interval of time in which the yam ends 3, 4 are pulled a correspondingly long distance, for example 200 mm., through the capacitors l, 2.

However, the above-mentioned possibility of discrepan-cies due to variations in cross section of the yarn can also be avoided by having the sensing means of the supervisory device respond to the diameter rather than to the volume of the yarn. FIG. 7 shows schematically an enlarged view of two yarn portions beside each other and having respectively different cross sections I and II. It is assumed that the cross section II is twice as large in area as the cross section I. Consequently, this illustration relates to a case of the most unfavorable ratio that may occur in the same yarn. If one scans the respective diameters a and b, either simultaneously or sequentially, and if the resulting values are then compared with each other, it will be found that even in this most unfavorable case the measuring values depart by at least 71% from each other. If the two yarns of I and II are alike, then a theoretical increase of 100% is involved in the area of II. Even in the event the yarn is not exactly of circular cross-sectional shape, there still remains an ample difference between a single diameter and a duplicated diameter, as has been confirmed by tests. The diameter scanning by suitable sensing means can be effected in the direction of the arrow x and in the direction of the arrow y of FIG. 7.

Particularly well suitable for thus scanning or sensing the yarn with respect to its diameter are photoelectric devices. For the purpose of the invention and according to another feature thereof, as shown in FIG. 8, such a sensing device comprises at least two light-

sensitive cells

31, 32 arranged at a right angle to each other, the yarn F to. be sensed being located at the intersection of the respective beams of light impinging upon the two cells. For example, one light beam can be oriented in the x-di- Jrection and the other beam in the y-direction of FIG. 7.

The two measuring values furnished by the respective voltages of the two photoelectric cells need then only be compared with each other, for example in a normally balanced bridge network. If the comparison results in a difference, the corresponding difference is then applicable as an output signal, for example to control a device that prevents the further processing of the yarn by actuating a cutting device 19 from a magnet 20 substantially as described above with reference to FIGS. 5 and 6, and to light a signal lamp L to alert the operator.

In the embodiment illustrated in FIG. 8, the yarnresponsive sensing device 125, mounted on the front of knotter 15 in place of the capacitor 1 or 2, is provided with two normally conducting

photocells

31 and 32 which are electrically connected in a bridge network normally balanced by means of an adjustable resistor 33 so that no voltage occurs between the output terminals C and D when the two

photocells

31 and 32 receive equal quantities of light. The respective light beams are preferably produced by a single light source 34 to obtain equal brightness of the two beams impinging upon the respective cells. In the illustrated embodiment of FIG. 8, therefore, with the thread being guided to normally pass in a position flat against one of the cells 32, the light from an incandescent lamp 34 passes through a lens 35 and through a prism 36 which divides it into two beams that are directed onto the

respective cells

31 and 32. Under normal operating conditions, with the yarn being guided, when a yarn end F passes through the sensing device, the light impinging upon each of the two

cells

31, 32 is reduced to the same extent so that the bridge network remains balanced. By arranging suitable yarn-guiding means along the yarn path, care can be taken for example that when two yarn ends reach the zone between the

cells

31, 32 of the sensing device they are always placed parallel to each other upon the lower photocell 32. Thusly, if two yarn ends instead of one are placed through the sensing device, the cell 31 receives more light than the cell 32, so that the bridge network becomes unbalanced. When thus the voltage of the lower photocell 32 is lower than the voltage from the lateral photocell 31, with switch 22 closed, the output bridge potential across points C and D is amplitied in amplifier 27 and applied to the cutter-control magnet 29 to operate the cutter 19 in the manner above described relative to FIGS. 4-6. The correct time for performing the sensing operation is controlled by the cam 21 of the tender 14 which operates above-mentioned switch 22. Current is supplied to the lamp 34 and to the amplifier 27 through a conventional supply unit corresponding to the one shown in FIG. 5.

Such a measuring device is generally applicable where it is desired to ascertain the presence of two or more threads. If the device is employed in conjunction with the type of knotter as exemplified by FIGS. 1, 2 and 3, the provision of a single photoelectric sensing device in place of the capacitor 1 or 2 in FIG. 1 is sufficient. On the other hand, if two photoelectric sensing devices are substituted for the respective capacitors at the localities according to FIGS. 1 and 2, the two pairs of output terminals C and D (FIG. 8) can be connected to one and the same amptitier so that the two photoelectric devices operate in parallel relation but independently of each other.

An embodiment of the invention related to the one just mentioned but further modified is illustrated in FIG. 9. Aside from the two photocells 31, 32 a sensing device of FIG. 9 is equipped with a third photocell 37. For simplicity, the light source 34 and its optical system of lenses 35 and prisms 36 are shown only schematically in FIG. 9 by the lamp 34 and the corresponding parallel beams of light. The photocells 31 and 37 are directly impinged upon by the light beams. whereas the light beam for the photocell 32 is deflected 90 with the aid of a mirror 38. A double thread F F is indicated as being located at the intersection point of the respective light beams for

cells

31 and 32. The light beams for cell 37 are not effected by the threads of yarn to be sensed. All three photocells in this embodiment are electrically interconnected to form two bridge networks. The upper bridge network, comprising ceils 31 and 37 as well as an adjustable resistor 39, produces along the load resistor 40 a voltage drop that corresponds to the diameter or dimension across the narrow side of the group of two threads F F and consequently corresponds to the measuring value in the xdirection of FIG. 7. The lower bridge network with the cells 31. 32 and a resistor 41 produces at the load resistor 42 a voltage drop which corresponds to the difference between the dimensions across the narrow side and the broad side of the double thread group and consequently corresponds also to the difference between the measurement in the x-direction and in the y-direction according to FIG.

The voltage drop of resistor 40, corresponding to the measuring value of the narrow dimension side of the thread group, is supplied to an amplifier 43 whose output voltage comprises a resistor 44 and is applied to another amplifier 45. The output voltage of amplifier 43 thus furnishes the threshold voltage for response of the amplifier 45, this threshold voltage corresponding to the diameter of the narrow side of the thread group. The amplifier 45 also receives the voltage from the resistor 42 corresponding to the above-mentioned dimension difference. As long as the voltage drop of resistor 42 is smaller than the threshold voltage at resistor 44, the amplifier 45 remains turned off and the yarn-cutter magnet 20 cannot respond. Only when the voltage from resistor 42 exceeds the minimum voltage furnished from amplifier 43, is the amplifier 45 effective to energize the cutter magnet 20 in FIG. 9.

A measuring system according to FIG. 9 has the advantage, relative to that of FIG. 8, that the thickness of the particular yarn being used has no influence upon the measuring result so that it is not necessary, when changing to yarn of different thread count, to newly adjust the measuring device.

The embodiments according to FIGS. 8 and 9 are predicated upon the possibility that the double threads are located firmly beside each other, for example against a support or guide, and that thereby the direction of the geometric line connecting the axes of these two threads is defined. However, a measuring device according to the invention for sensing the yarn diameter can also be employed if the threads cannot be placed flat upon the support. The diameter scanning can then be effected for example by turning or swinging the threads in the measuring location about their common axis, or by turning or swinging the sensing device, namely the light source, optical system and photocells about the threads, as shown in FIGS. 10 and 11.

According to this embodiment of the invention, as shown in FIGS. 10 and 11, swinging movement is imparted to the sensing device about the pivot P, located in the zone through which the thread group to be tested passes, by means of drive means comprising a crank disc or cam 119 acting through a linking member or connecting rod 118. The crank disc 119 is provided with a T- groove 120 in which a pin 119a attached to the end of connecting rod 118 is slidable. Rod 118 is pivoted at 118a to the housing 139 of the sensing device. The crank disc 119 can be rotated about its central axis 121 by an electric motor provided with a reduction gear drive (not shown). As the disc 119 rotates, the point 11811 describes an are A about the pivot axis P to scan the zone of the threads. If two threads actually are present, at some location within the path of the housing during its swinging motion about P, there will be a difference of light on the

respective photocells

31, 32, thereby causing a voltage potential to actuate the cutter 19 through magnet 20. Thus, the housing will oscillate continuously in its scanning operation to detect the presence of two or more threads, irrespective of the location of the threads within the zone between the cells, or their exact alignment relative to the

photocells

31, 32, or of the alignment of the geometric line connecting the axes of the two threads.

Another way of performing a diameter-responsive sensing in such cases is to pass the threads through a stationary sensing device which possesses at least three sensing axes. The difference within the three axes then indicates the diameter difference. In some cases, a single photoelectric beam and cell is sufficient. This is the case when the measuring values resulting from the individual directions are memorized in an electric storer and are subsequently compared with each other. Such a time sequence of the measuring operations in different sensing directions is applicable only when the yarn is at rest, whereas travelling threads require performing the measurements simultaneously.

It will be apparent from the foregoing that the invention is not limited to the above-described illustrated embodiments, presented by way of example, but can be modified in various other respects. For example, in the embodiment of FIG. 9, there can be used, in lieu of the two bridge networks of photocells 31/37 and 31/32, two measuring bridges both of which include the photocell 37, namely a measuring bridge comprising the photocells 37, 31 as in the embodiment of P16. 9, and a second measuring bridge comprising the photocells 37 and 32. Furthermore, the diameter-responsive control can be effected not only with the aid of photoelectric devices operating with beams of light, but also by other sensing means. For example, the diameter can be ascertained with the aid of a so-called ion-spot sensor operating as follows. A highfrequency corona discharge is applied locally to the travelling yarn as it passes between two electrodes of which one is designed as a point electrode directed toward the yarn. Due to the corona discharge, in whose field the yarn is located, a spot on the yarn is ionized and retain an electric field which travels together with the yarn. The electric charge is applied to the yarn before it approaches the knotter. Near the knotter the yarn passes through another group of electrodes close to the yarn on diametrically opposite sides thereof but spaced therefrom. One of the two electrodes may again be pointed toward the yarn. The two electrodes are connected to a measuring circuit. When two ends of yarn are located beside each other, the field effect of the ionized yarn upon the electrode circuit differs from that occurring when only a single yarn end passes between the electrodes, so that the device can be made to respond substantially in the same manner as described above.

The invention is further applicable not only for determining the occurrence of double threads in the knotter, but generally for determining the occurrence of a given number of threads at the sensing location or the departure of the thread number from a given value. This applies particularly to the above-described embodiments provided with at least two photoelectric cells arranged at a right angle to each other. To prevent accumulation of dust in the light-beam path of such devices, it is often of advantage to pass a current of suction or blowing air through the measuring gap and, if desired, to provide known means for preventing or eliminating electrostatic charges.

Such and other modifications will be obvious to those skilled in the art, upon a study of this disclosure, and are indicative of the fact that our invention permits of a great variety of variations and hence can be given embodiments other than particularly illustrated and described herein, without departing from the essential features of the invention and within the scope of the claims annexed hereto.

We claim:

1. Apparatus for monitoring yarn being wound, comprising a yarn knotter provided with means for receiving two yarn ends to be knotted together and defining for each yarn end a yarn path through said knotter, yarn-proximity sensing means positioned adjacent said yarn paths for receiving said respective yarn ends, electrical circuit means comprising a bridge network connected across said sensing means and responsive into unbalanced condition upon sensing by said sensing means of mutually unequal presence of yarn along said two paths, high frequency generator means for energizing said circuit means, said bridge network when in said unbalanced condition having a voltage potential across the terminals thereof, an amplifier connected across said terminals for amplifying said potential to produce an actuating signal, and yarn blocking means connected to said amplifier for actuation by said signal to interrupt further yarn travel upon occurrence of unbalance of said bridge network.

2. Apapratus for monitoring yarn being wound, comprising a yarn knotter provided with yarn tying beaks and with means for receiving two yarn ends to be knotted together, said receiving means defining for each yarn end a yarn path through said knotter, yarn-proximity sensing means positioned adjacent at least one of said yarn paths, said sensing means comprising two capacitors of normally equal impedance mounted adjacent said beaks for receiving said respective yarn ends, electrical circuit means comprising a bridge network having resistance means and connecting said two capacitors in parallel and responsive into unbalanced condition upon sensing by said sensing means of mutually unequal presence of yarn along said two paths, high frequency generator means for energizing said circuit means, said bridge network when in said unbalanced condition having a voltage potential across the terminals thereof, an amplifier connected across said terminals for amplifying said potential to produce an actuating signal, blocking means including a solenoid connected to said amplifier for actuation by said signal, and cutter means linked to said solenoid for cutting one of said yarn ends to prevent tying operation of said knotter when said two capacitors sense mutually unequal presence of yarn.

3. Apparatus for monitoring yarn being wound, comprising means defining a yarn path for yarn, yarn-proximity sensing means positioned adjacent said yarn path and sensitive to departure of diameter of the yarn from a predetermined value, measuring means comprising a bridge network connected across said sensing means and responsive into unbalanced condition upon sensing by said sensing means of said departure of yarn diameter, said bridge network when in said unbalanced condition having a voltage potential across the terminals thereof, and signal receiving means connected to said terminals for actuation by said voltage potential.

4. Apparatus according to claim 3, said signal receiving means comprising a protective device for preventing further processing of the yarn being wound.

5. Apparatus according to claim 4, said protective device including a magnet arranged to be actuated by said voltage potential, an armature movable by said magnet, and yarn severing means connected to said armature for serving yarn along said path.

6. Apparatus for monitoring yarn being wound, comprising a yarn knotter provided with means defining a yarn path through said knotter, yarn-responsive sensing means mounted on said knotter adjacent said yarn path and responsive to variations in the presence and diameter of yarn along said path, a measuring device having discriminating means connected to said sensing means, and signal receiving means connected to said measuring device and controllable thereby in dependence upon response of said sensing means.

7. Apparatus according to claim 6, said sensing means comprising electric capacitors, said measuring device comprising a capacitance measuring circuit, and said discriminating means comprising a variable resistance.

8. Apparatus for monitoring yarn being wound, comprising a yarn knotter provided with means for receiving two yarn ends to be knotted together and defining for each yarn end a yarn path through said knotter, two capacitors mounted on said knotter at diametrically opposite locations, said capacitors each having a yarn-receiving gap forming part of a respective yarn path, said capacitors having normally mutually equal inductance but variable in dependence upon difference in presence and diameter of yarn in said respective gaps, a normally balanced bridge network connecting said capacitors and arranged to become unbalanced upon difference in inductance occurring in said capacitors, said bridge network when in unbalanced condition having a voltage potential across the terminals thereof, and signal receiving means connected to said terminals for actuation by said voltage potential.

9. Apparatus according to claim 6, said signal receiving means comprising a yarn severing device mounted along said yarn path ahead of said knotter as considered in the yarn travel direction.

10. Apparatus according to claim 6, said sensing means including photoelectric cell means mounted adjacent said yarn path, and light beam means providing at least one light beam directed toward said cell means and across said yarn path.

11. Appartus according to claim 10, said cell means comprising a plurality of photoelectric cells, at least two of said cells being positioned at right angles to each other, said light beam means including a prism arranged to direct two light beams at right angles to each other to impinge upon respective ones of said two cells, the intersection of said two light beams being on said yarn path.

12. Apparatus according to claim 11, said plurality of photocells including a third photocell mounted adjacent said yam path, said means providing a light beam including means for directing a third light beam to impinge on said third cell and extending outside of said yarn path.

13. Apparatus according to claim 10, said light beam means having a single source of light, and light deviating means arranged to direct light from said source into a plurality of light beams for impinging on said respective cell means.

14. Apparatus according to claim 10, including means for turning said sensing means relative to the axis of the yarn path.

References Cited by the Examiner UNITED STATES PATENTS 3,030,040 4/1962 Reiners 24235.6 3,063,007 11/1962 Baugh et a1. 2864 3,077,312 2/1963 Furst 242-35.6 3,106,762 10/ 1963 Riera 28-64 3,132,407 5/ 1964 Glastra 28-64 DONALD W. PARKER, Primary Examiner.