GB2383802A

GB2383802A - Yarn break detector

Info

Publication number: GB2383802A
Application number: GB0200048A
Authority: GB
Inventors: Nicholas Stanier
Original assignee: New House Textiles Ltd
Current assignee: New House Textiles Ltd
Priority date: 2002-01-03
Filing date: 2002-01-03
Publication date: 2003-07-09
Also published as: GB0200048D0

Abstract

A yarn break detector comprises fixed yarn guide means 24, moveable yarn guide means 26 moveable between a first position in which it aligns, generally, with the fixed yarn guide means 24 and a second, signalling position, bias means 42 urging the moveable yarn guide means 26 towards its second position, and an adjustment arrangement 38 operable to adjust the magnitude of the biasing force applied to the moveable yarn guide means 26. The mechanism 38 may comprise a bar on which are anchored springs 42 biassing respective guide means 26 associated with a series of yarns, the bar being axially movable to allow the engagement of an arm 48 with a selected detent 50 to adjust the bias applied by the springs. In the signalling position for a broken yarn a projection 44 integral with the guide means 26 blocks a light beam passing through an opening 46.

Description

Yam Break Detector This invention relates to a detector for use in sensing when a break has occurred in one or more yams, threads, filaments or wires being supplied, for example, to a weaving loom.

A known yam break detector comprises a pair of fixed eyelets through which a yam, thread, filament or wire (hereinafter referred to as the yam) passes.

Between the fixed eyelets is a moveable eyelet through which the yam passes.

The yam holds the moveable eyelet in general alignment with the fixed eyelets against the action of a biasing arrangement. Upon the yam breaking or a spool becoming empty, the moveable eyelet moves under the action of the biasing arrangement, the movement signalling the presence of a yam break condition.

In order to operate reliably, but not cause false alarms, it is desirable to be able to adjust the operation of the detector to compensate for differing operating tensions, yam weights or other parameters, and it is an object of the invention to provide a detector permitting such compensation.

According to the present invention there is provided a yam break detector comprising fixed yam guide means, moveable yarn guide means moveable between a first position in which it aligns, generally, with the fixed yam guide means and a second, signalling position, bias means urging the moveable yarn guide means towards its second position, and an adjustment arrangement

operable to adjust the magnitude of the biasing force applied to the moveable yam guide means.

The use of an adjustment mechanism allows a relatively large biasing force to be applied, for example when used with heavy yarns, to ensure reliable signalling, and smaller biasing forces to be applied when lighter yarns are used thereby reducing the risk of false triggering of signals representative of a yam break.

Conveniently, the bias means comprise a spring, for example a torsion spring, and the adjustment arrangement comprises means for applying a prestressing load to the spring. The adjustment arrangement conveniently comprises a moveable anchorage associated with the spring. Where the spring is a torsion spring, the moveable anchorage is conveniently angularly moveable to adjust the pre-stressing of the spring.

The yam break detector conveniently includes several moveable yam guide means each being independently biased, a common adjustment arrangement being operable to vary the biasing force applied to each moveable yam guide means.

The yam break detector conveniently further comprises sensor means, for example optical sensor means, for sensing when the moveable guide means occupies its second position.

The invention will further be described, by way of example, with reference to the accompanying drawing (Figure 1) which is a perspective view, partly exploded and which some parts are omitted for clarity, of a yam break detector in accordance with an embodiment of the invention.

The yam break detector illustrated in Figure 1 comprises a mounting plate 10 adapted to be secured in a suitable location past which a number of threads, filaments wires or yams extend. The device further includes an end plate 12 secured to the mounting plate 10 by means of front and rear mouldings or extrusions 14,16. The mounting plate 10 and end plate 12 are secured to the mouldings or extrusions 14,16 by means of screws, bolts or any other securing means. The mounting plate 10, end plate 12 and extrusions or mouldings 14,16 together define a housing containing a plurality of yam break detector modules 18. Each of me yam break detector modules 18 comprises a housing 20 defining a pair of upstanding locations 22 adapted to carry ceramic eyelets 24 which serve to guide the passage of a thread or yam or the like over the yam break detector. Between the eyelets 24 is located a moveable yam guide means in the form of a further eyelet 26 carried by an arm 28 which extends into the housing 20 and is pivotally mounted upon a hub 30 forming part of the housing 20.

In order to restrict the entry of dust into the housing 20, in use, the housing 20 is provided with a baffle 32 arranged to direct dust or fluff through

an opening formed in the lower part of the housing 20. Further, the housing 20 is shaped to define walls 34 co-operable with a guard 36 carried by the arm 28 to restrict the entry of dust or fluff into the housing 20.

As described hereinbefore, the yam break detector includes a plurality of yam break modules 18 located in side-by-side configuration. A bar 38 extends through the hubs 30 of each of the modules 18, the bar 38 being supported by the end plate 12 and mounting plate 10 through bearings 40 to permit the bar 38 to be moved angularly relative to the modules 18. A torsion spring is located over the hub 30 of each module 18, one end of the torsion spring 42 being secured to the respective arm 28, the other end of each torsion spring 42 being located within an elongate groove formed in the bar 38. The spring 42 serves to bias the respective arm 28 away from the position shown in Figure 1 towards a raised, signalling condition. In this position, the eyelet 26 thereof is out of alignment with the eyelets 24. The movement of the arm 28 moves an integral projection 44 thereof to a position in which it obscures an opening 46 formed in the housing 20.

An actuator arm 48 is mounted upon an end of the bar 38. The actuator arm 48 is provided with a projection co-operable with recesses 50 formed in the end plate 12. A further projection formed on the actuator arm 48 rides within an arcuate slot 52 formed in the end plate 12 to control the maximum range of

permitted angular movement of the actuator arm 48. The mounting of the actuator arm 48 upon the bar 38 is such as to allow a degree of axial movement of the arm 48 relative to the bar 38 to allow the projection of the arm 48 to be lifted out of co-operation with the recesses 50, a spring biassing arrangement being provided to bias the actuator arm 48 to an axial position in which the projection is located within one of the recesses 50.

In use, a yam or thread or the like to be monitored using the yam break detector is fed through one of the eyelets 24, through the eyelet 26 carried by the associated arm 28 and through the other eyelet 24. The yarn then passes to the weaving loom or other device with which the yam break detector is being used.

The yarn is placed under tension by, for example the weaving loom, the tension in the yam being sufficient to hold the arm 28 in the position shown in Figure 1 against the action of the biasing force applied by the spring 42. In the event of a breakage occurring in the yarn, the spring biasing of the arm 28 urges the arm 28 away from the position shown in Figure I to a position in which the eyelets 26 is raised out of alignment with the eyelets 24. As described hereinbefore, such movement causes the projection 44 to overlie the opening 46. Although not illustrated, an optical monitoring arrangement is included in the yam break detector device, the optical monitoring arrangement including a light beam or pattern of beams which passes through the openings 46 of each of the yam break

detector modules 18, and a sensor arranged to monitor the light beam or beams.

In the event of one of the arms 28 moving the raised position, it will be appreciated that the light beam will be broken. Upon sensing that the light beam has been broken, a suitable signal can be supplied to the control circuits for the weaving loom or other device with which the yarn break detector is being used to cause operation thereof to cease.

Depending upon the nature of the yam with which the device is being used, the magnitude of the biasing load applied to the arm 28 by the spring 42 can be adjusted by movement of the actuator arm 48 to appropriately control the degree of pre-stressing of the spring 42. Thus, for example, where a relatively heavy yam is being used, in the event of a breakage occurring in the yam at some distance from the yam break detector, a significant weight of yam must be moved by the arm 28 for the arm 28 to move to its signalling position. In order to ensure that the yam break detector operates reliably under such circumstances, it is desirable for the spring 42 to be pre-stressed by a significant amount. Where the yam break detector is used with relatively light yams, or where the device is used in a system in which the yams are held under a relatively low tension, such large pre-stressing of the spring 42 may result in the device producing numerous false alarm signals. Under such circumstances, it may be appropriate to reduce the pre-stressing of the spring 42, and this is achieved by moving the actuator

arm 48 to rotate the bar 38 to reduce the pre-stressing of the spring 42.

It will be appreciated that where several modules 18 are present, the prestressing of the springs 42 can result in the bar 38 experiencing a large force urging it to rotate. The provision of the projection on the arm 48 which is cooperable with the recesses 50 is intended to prevent such rotation occurring by locking the bar 38 in its selected angular position. If it is desired to change the angular position of the bar 38, then this locking must be dis-engaged and this is achieved by pulling the arm 48 away from the end plate 12 to withdraw the projection from the recess 50. Once the desired angular position has been reached, release of the arm will re-engage the lock under the action of the axial spring biasing of the arm 48.

If the yam break detector device contains more yam break detection modules 18 than is required, then it will be appreciated that for the yam break detector device to operate correctly, one or more of the arms 28 must be held in its lower position in order to avoid the triggering of an alarm signal. In order to do this, each module 18 is conveniently provided with a lock-down arrangement whereby each of the arms 28 can be locked in its lowermost position.

Although in the description hereinbefore the yam guide means take the form of eyelets 24,26 it will be appreciated that other techniques may be used for guiding the yams through the device, and the invention is applicable to the

use of any such techniques.

Although in the description hereinbefore reference is made to the breakage of a yam, it will be appreciated that the device is also sensitive to a spool of yarn becoming empty as this will result in the yam tension falling to a degree sufficient for a signal to be produced.

Claims

1. A yam break detector comprising fixed yam guide means, moveable yam guide means moveable between a first position in which it aligns, generally, with the fixed yam guide means and a second, signalling position, bias means urging the moveable yam guide means towards its second position, and an adjustment arrangement operable to adjust the magnitude of the biasing force applied to the moveable yam guide means.

2. A detector according to Claim 1, wherein the biasing means comprises a spring.

3. A detector according to Claim 2, wherein the spring is a tension spring.

4. A detector according to Claim 2 or Claim 3, wherein the adjustment arrangement comprises means for adjusting the magnitude of a pre-stressing load applied to the spring.

5. A detector according to Claim 4, wherein the adjustment mechanism comprises a moveable anchorage associated with the spring.

6. A detector according to Claim 5, wherein the moveable anchorage is angularly moveable.

7. A detector according to any one of the preceding claims, further comprising sensor means for sensing when the moveable guide means occupies its second

position.

8. A detector according to Claim 7, wherein the sensor means comprises an optical sensor arrangement.

9. A detector according to any one of the preceding claims, further comprising at least one additional moveable yam guide means, each being independently biased, the adjustment arrangement being operable to adjust the magnitude of the biasing force applied to each moveable yam guide means.

10. A yam break detector substantially as hereinbefore described with reference to the accompanying drawing.