GB2046317A

GB2046317A - Yarn detectors

Info

Publication number: GB2046317A
Application number: GB8011139A
Authority: GB
Original assignee: Spencer Wright Industries Inc
Current assignee: Spencer Wright Industries Inc
Priority date: 1979-04-10
Filing date: 1980-04-02
Publication date: 1980-11-12

Abstract

Changes in yarn tension are monitored, particularly in the context of multiple yarn feed from a creel to a tufting machine, so that warning can be given of a fault condition such as a broken or tight yarn end. For each yarn end there is a respective yarn tension detector (33) which may comprise a pivotally mounted wire frame (11) with opposite guide formations (14, 15) around which the yarn (13) runs. A fault condition causes the frame to pivot away from a central position to one of two limit positions at which an electric signal is produced by closure of electrical contacts (11, 16, 17). The signal is fed to a remote electronic system which produces a remote visual indication, such as a digital read-out which identifies the location of the fault condition in the creel. <IMAGE>

Description

SPECIFICATION Yarn detectors This invention concerns yarn tension detectors, and has particular, though not exclusive, reference to yarn tension detectors for use in the context of.

multiple yarn feed from creels to tufting machines.

In the production of tufted carpets and like materials, the problem arises that the high rate of output of conventional tufting machines is such that a substantial length of material containing a fault due, for example, to a broken ortightyarn end might be produced before the fault is detected and the yarn in question identified, with consequential financial loss to the manufacturer.

One object of the present invention is to overcome or at least appreciably reduce this problem, and a further object is to provide a simple and covenient yet sensitive and reliable yarn tension detector which is capable of monitoring any substantial deviation from a norm of the tension in a yarn.

According to one aspect of the invention therefore there is provided an assembly of yarn tension detectors each arranged to undergo a monitorable change in a state thereof in response to detection thereby of a predetermined change in the tensioning of a respective yarn engaged therewith, characterised in that said detectors are collectively adapted and arranged to provide a remote indication capable of identifying the location of one said detector undergoing said monitorable change.

With this arrangement it will be appreciated that detection and rapid identification of the location of a yarn tension fault can be much facilitated.

Preferably, said monitorable changed involves the production of an electrical output and the detectors are connected to a remote display system which is arranged to be actuated by any said electrical output to produce said remote indication.

With regard to the remote display system, this may provide complete information with regard to the identity of the said location and/or it may provide only partial information which is required to be supplemented by examination of certain ones of the detectors to enable a specific fault-indicating said detector to be identified. In the former respect, suitably an alphanumeric digital display device may be utilised to give information in letters and/or numbers to identify a specific detector.In the latter respect, suitably, and in the case of a creel having multiple yarn tension detectors arranged in multiple alleys, each detector may incorporate a signal lamp and/or a movable signal element or other device which can give a fault indication local to the detector, and the detectors of each alley may be connected to a common alley indicator which can give a remote indication of the detection of a fault by one such detector of the pertaining alley.

According to a further aspect of the present invention there is proposed a yarn tension detector, particularly for use in an assembly as described above, comprising a displaceable member movable between predetermined limits at either side of a datum under the control of the tension of a moving yarn engaged therewith and according to such tension, the said member having laterally spaced, oppositely directed guide formations within which a yarn is trained and being so adapted and arranged as to cause the said member to assume a respective one of the limits in conditions of high or low tension respectively.

According to a preferred feature, the displaceable member moves to the predetermined limit corresponding to the condition of high tension against the restraint of a resilient means.

According to a further preferred feature the said oppositely directed guide formations are adapted progressively to be opened by yarn tension so that they grip the yarn with light pressure and thus prevent the said displaceable member from making contact with the limit corresponding to a broken end provided that tension is maintained in the outgoing yarn.

According to a further preferred feature, the displaceable member is mounted for pivotal motion between the said limits.

According to a further preferred feature, the displaceable member is co-operable with indicator means sensitive to the position of the displaceabie member, which indicator means can be used to initiate production of a visual or audible indication on movement of such member to one or other of the said predetermined limits. Thus, for example, the displaceable member may be arranged to make or break respective electric contacts at the two said limits. Alternatively or additionally, the member may have associated therewith a signal element which adopts different predetermined visual distinguishable signalling positions according to whichever of the said limits is contacted by the member.

The invention will now be described further, by way of example only, with reference to the accompanying drawings illustrated one embodiment there- of and in which: Figure 1 is a diagrammatic perspective view of one form of a yarn tension detector according to the present invention in a position corresponding to a normal yarn feed; Figures 2a to 2d are diagrammatic views illustrating the operation of the detector in sensing high and low tensions; and Figure 3 is a circuit diagram of an assembly of multiple yarn tension detectors of the kind shown in Figure 1 in conjunction with a remote display system.

Referring now to the drawings, and particularly to Figure 1 thereof, a yarn tension detector comprises a displaceable member 11 mounted for pivotal motion about a remote axis 12 under the control of the tension in a yarn 13 engaged with laterally spaced, oppositely directed guide formations 14,15thereon.

The displaceable member is movable between limits determined by spaced abutments 16, 17 lying in the path of movement of the displaceable member, the abutments 16, 17 being contacts or terminal als in an electrical circuit forming part of a display system capable of providing a visual indication representative of the occurrence and location of a substantial deviation of the tension from a norm in one of a pluralityofyarns in a creel, such system being shown in Figure 3 and being described in detail hereafter.

The displaceable member 11 is fabricated from a continuous length of wire bent into generally rectangular cage-like form, the two ends of the wire lying in parallel side-by-side disposition longitudinally of the top of the member, one such end being shortened and bent through 90 to lie in the plane of the top of the member to provide a self-threading device 18 and the other end extending beyond the rear end of such top and being coiled to define a support spring for mounting the displaceable member, the remote end of the wire which forms the coil spring 19 defining an outwardly extending tail 20 for a purpose hereafter to be made apparent.

At the forward end of the displaceable member the parallel, side-by-side ends of the wire diverge to form a throat which defines the first guide formation 14, the diverging wire portions lying in the plane of the top of the member and such portions being bent downwardly through 90 to follow the front edges of the notional rectangular cage and then through a further 90 to follow the bottom edges of the cage.At the rearward end of the displaceable member, those wire portions which follow the bottom edges of the notional rectangular cage are bent upwards along the line of the related edges of such cage and then are bent inwardly through approximately 90 to lie in a common plane parallel to the top and bottom faces of the rectangular form and approximately mid-way between such faces, the wire portions converging and meeting threat to define the second guide formation 15.

The outwardly extending tail 20 has an electrically insulating sleeve 21 thereon, and is of such length and disposition as to be engageable with abutment 17 prior to engagement of the displaceable member 11 with abutment 16 thereby to provide a restraint to movement of the displaceable member into engagementwith abutment 16.

In threading up the detector, a generally vertically disposed yarn 13 is offered up to the rearward end of the displaceable member 11, and is passed between the adjacent parallel ends of the wire, to the throat formed by the diverging wire portions, the engage mentwith and the separation of such parallel ends against the inherent resilience of the wire being facilitated by the laterally extending self-threading device, the yarn thereby engaging the first and second guide formations 14,15.

In conditions of normal yarn tension,the displace able member i 1 oscillates between the angular dispositions shown generally in Figures 2a, 2b, engagement of the tail 20 with the related abutment 17 maintaining the displaceable member out of contact with abutment 16.

In the case of a tension in excess of the normal yarn tension, the displaceable member 11 is pivoted upwardly beyond the position shown in Figure 2b against the restraint of the spring 19 of which the tail 20 forms an extension and into contact with abutment 10, (Figure 2c), thereby to complete and electrical circuit of which the displaceable member and the abutment 16 form a part.

As will be appreciated, in the event of a yarn tension sufficient to overcome the resistance to displacement of the adjacent parallel ends of the wire which forms the displaceable member, the yarn will automatically be withdrawn from the detector, but the restraint derived from the tail extension of the spring will be so selected as to ensure contact between the displaceable member and abutment 16 before withdrawal of the yarn from the guide formations.

In the event of a slack (or broken) outgoing yarn the displaceable member pivots downwardly under gravity into engagement with the lower abutment 17, (Figure 2d) thereby to complete an electrical circuit of which the displaceable member and abutment 17 form a part.

In the embodiment illustrated, the displaceable member and abutments are electrically conductive and form part of an electrical circuit operable to initiate production electrically of a visual indication representative of the occurrence and location of a high or low yarn tension. However, it will be noted that a visual indication of high or low yarn tension is obtained by reference to the position of the tail extension to the spring, the non-conducting sleeve applied to such tail being brightly coloured to improve its visibility, and it may be found sufficient in some circumstances to rely on this mechanical change as the sole local indication of a yarn tension fault.

Preferably, however, and as shown in Figure 3 of the drawings, the yarn tension detector is used with a plurality of like detectors in a creel feeding multiple yarns to a tufting machine and such detectors are arranged in a display system operable to produce electrically both local and remote visual fault indications.

The creel has a respective said yarn tension detector 33 for each yarn end, such detectors 33 being arranged in a plurality of creel alleys. in Figure 3, only four detectors in two alleys 21, 22 are shown for the sake of clarity. A yarn tensioning fault causes the displaceable member 11 of the pertaining detector 33 to move from an intermediate position (as shown in the drawings) into contact with the electrical terminal 16, 17 on one or the other side thereof.

The terminals 16, 17 ae connected via respective diodes 24to a signal lamp 23 of the detector, which lamp is connected to a first positive supply potential 25, and the member 11 is at grount potential.

Accordingly, such contact between the member 11 and one terminal 16, 17 enables a current to flow through the signal lamp 23 of the detector which is thereby illuminated giving local indication of the occurrence of the yarn tension fault. The lamps 23 are connected to the positive supply potentail 25 in a number of separate groups across the alleys 21, 22 via respective sensors 26. When any lamp 23 is illuminated in any one said group, the pertaining sensor feeds an electrical signal (which may be simply a voltage drop at a junction or across a resistance) to a respective input of a control circuit 27.

The terminals 16, 17 of all detectors in each creel alley are connected via respective diodes 28 to a second positive supply potential 29 via respective indicators 30 at the end of the alley, whereby the aforesaid contact occurring between the member 11 and one termnal 16, 17 of any detector 33 causes one of the indicators 30 (depending which terminal 16, 17 is contacted) at the end of the pertaining alley to be actuated to feed an electrica signal to an input of the control device 27 and also to effect illumination of a signal lamp or the like incorporated in such indicator 30. With this arrangement, in the event that a fault occurs, the location of the fault can be found quickly and easily by noting the actuated alley indicator 30 and then examining the lamps 23 of the individual detectors 33 of such alley.

The control device 27 has an output connected to a digital display unit 31 located alongside the creel.

The control device 27 incorporates microprocessor controlled processing circuitry and the unit 31 has a bank of cathode ray tube digitial display devices. In the event that a fault occurs, electrical signals fed to the inputs of the device 27 as described above are appropriately processed and utilised to effect actuation of the unit 31 so that a remote numerical digital display is produced which specifically identifies the location of the fault. The device 27 also has a data output 32 thereto and a code signal is produced at such output corresponding to the numerical display produced on the unit 31. Such code signal can be fed to a remote central processing unit for utilisation for information purposes as described in our copending Application No. 7917450. In this way, detailed information concerning yarn tension faults can be collected in a particularly simple and convenient manner.

It is of course to be understood that the invention is not intended to be restricted to the details of the above embodiment which are described by way of example only.

Claims

1. An assembly of yarn tension detectors each arranged to undergo a monitorable change in a state thereof in response to detection thereby of a predetermined change in the tensioning of a respective yarn engaged therewith, characterised in that said detectors are collectively adapted and arranged to provide a remote indication capable of identifying the location of one said detector undergoing said monitorable change.

2. An assembly according to claim 1, wherein said monitorable change involves the production of an electrical output and the detectors are connected to a remote display system which is arranged to be actuated by any said electrical output to produce said remote indication.

3. An assembly according to claim 2, wherein said remote indication comprises an alphanumeric display.

4. An assembly according to claim 2 or 3, wherein said remote indication comprises illumination of a lamp.

5. An assembly according to any one of claims 2 to 4, wherein said detectors are connected to the remote display system using multiplexing techniques.

6. An assembly according to any one of claims 2 to 5, wherein there is a different said remote indication for each detector.

7. An assembly according to any one of claims 2 to 5, wherein said detectors are connected in groups and the display system is arranged to produce the same remote indication for all detectors in each group.

8. An assembly according to any one of claims 2 to 7, wherein each detector is connected to a respective local indicator which is arranged to be actuated on production of the said electrical output by said detector.

9. An assembly according to claim 8, wherein said local indicator comprises an electric lamp.

10. An assembly according to claim 8, wherein said local indicator comprises a movable signal element.

11. A yarn tension detector particularly for use in an assembly according to any one of the preceding claims, comprising a displaceable member movable between predetermined limits at either side of a datum under the control of the tension of a moving yarn engaged therewith and according to such tension, the said member having laterally spaced, oppositely directed guide formations within which a yarn is trained and being so adapted and arranged as to cause the said member to assume a respective one of the limits in conditions of high or low tension respectively.

12. A detector according to claim 11, wherein the displaceable member is arranged to move to the predetermined limit corresponding to the condition of high tension against the restraint of resilient means.

13. A detector according to claim 11 or 12, wherein the oppositely directed guide formations are adated progressively to be opened by yarn tension so that they grip the yarn with light pressure and thus prevent the said displaceable member from making contact the the limit corresponding to a broken end provided that tension is maintained in the outgoing yarn.

14. A detector according to any one of claims 11 to 13, wherein the displaceable member is mounted for pivotal motion between the said limits.

15. A detector according to any one of claims 11 to 14, wherein the displaceable member is arranged to make or break respective electric contacts at the two said limits.

16. A detector according to any one of claims 11 to 15, wherein the displaceable member has associated therewith a signal element which adopts different predetermined visually distinguishable signallig positions when the member is at said limits.

17. A detector according to claim 11, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

18. An assembly according to any one of claims 1 to 10, wherein each detector thereof is as claimed in any one of claims 1 to 16.

19. An assembly according to claim 1 substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

20. An assembly according to any one of claims 1 to 10, 18 and 19, when applied to a yarn creel arrangement having a plurality of alleys thereto, the said remote indication being capable of identifying at least the alley in which is located one said detector undergoing said change.

21. An assembly applied to a yarn creel arrangement according to claim 20 when used with a tufting machine.