WEFT YARN METERING DEVICE

Abstract: A yarn metering device (10) including a stationary spool (12), a yarn supply arm (14) for wrapping yarn onto a storage region (24) of the spool (12), a yarn guide arm (17) for simultaneously transferring yarn from the storage region (24) and wrapping it onto a discharge region (25) of the spool (12) and stop means (20) co-operable with the discharge region (25) of the spool (12) for permitting yarn (16) wrapped on the discharge region (25) to be pulled axially off the spool (12) after a predetermined quantity of yarn (16) has been wrapped onto the discharge region (25).

Description: WEFT YARN METERING DEVICE The present invention relates to a metering device for use in a fluid jet loom for metering the amount of weft yarn supplied across the warp shed on each weaving cycle of the loom. A yarn metering device including a stationary spool, a yarn supply arm for wrapping yarn onto a storage region of the spool, a yarn guide arm for simultaneously transferring yarn from the storage region and wrapping it onto a discharge region of the spool and stop means co-operable with the discharge region of the spool for permitting yarn wrapped on the discharge region to be pulled axially off the spool after a predetermined quantity of yarn has been wrapped onto the discharge region. Various aspects of the present invention are hereinafter described with reference to the accompanying drawings in which:- Figure 1 is a schematic perspective illustration of part of a device according to the present invention; Figure 2 is a more detailed axial section through a device according to the present invention shown mounted on part of a loom; and Figure 3 is a cross-sectional view taken along line III-III in Figure 2. Referring initially to Figure 1, the device 10 according to the present invention includes a fixed spool 12 which is of generally cylindrical shape, and a yarn supply arm 14 which extends radially from the axis of the' spool and which is rotatably mounted for rotation about said axis. The arm 14 is hollow and is cranked so as to be able to wrap yarn " 16 about the spool as will be described in greater detail later. The device also includes a yarn guide arm 17 which is conveniently diametrically opposed to the arm 14 and is rotatable in unison therewith. The guide arm 17 picks up yarn deposited by arm 14 and re-wraps the yarn on the spool at a position further along the spool. The device also includes a yarn stop finger 20 ' BUREAU _«., .—-»—-«—..-—.-— r"> ' -r—"T I OMPI which controls release of yarn from the spool 12 and initiates winding of yarn onto the spool by guide arm 17. As illustrated in Figure 1 the device 10 is arranged to supply yarn to an air jet nozzle 22 which drives the yarn across the warp shed of the loom (not shown). As indicated above, yarn 16 is wrapped onto the spool at two different locations on the spool 12. These locations 24, 25 respectively are separated by a ridge 26 so that the locations are physically separated. At location 24 before operation of the device 10 the yarn is wrapped about the spool 12 by a predetermined minimum number of turns to define a supply coil of yarn 28. Accordingly, location 24 forms a storage region of the spool. The supply coil of yarn 28 has basically two main functions, viz to provide a supply of yarn for yarn guide arm 17 and to prevent slippage of yarn on the spool 12 as the arm 14 draws yarn from the yarn package (not shown). During each weaving cycle of the locra, arms 14 and 17 are continually rotating so that arm 14 winds onto the spool a supply of yarn which is picked up and rewound onto the spool by arm 17. Accordingly since the rate of winding of arm 14 is the same as the rate of unwinding of the guide arm 17 the size of the supply coil 28 remains constant. As guide arm 17 wraps yarn onto the spool 12 the stop finger 20 moves axially ' along the spool away from arms 14 and 17. At a predetermined time in the weaving cycle after shedding of the warp yarns the finger 20 is moved radially away from the spool to allow the yarn wound thereon by arm 17 to be pulled off by the jet nozzle 22, from location 25 which defines a discharge region of the spool. The finger 20 is simultaneously moved axially back toward the arms 14 and 17 and then moved radially inwardly to enable arm 17 to initiate wrapping of yarn about the spool. The cycle is then repeated. The constant length of yarn stored on the spool in the supply 28 is basically dependent on two variables, viz the number of revolutions made by arm 17 in each cycle and the diameter of the spool. The number of revolutions is controlled by a suitable choice of gearing ratios in drive from the main loom drive shaft and the spool is preferably constructed so that its diameter may be adjusted. Accordingly the amount of yarn stored on the spool may be accurately and easily adjusted. Additionally, by suitably timing when the stop finger is moved radially inwardly to catch the yarn being wrapped by the guide arm 17 it is possible to achieve two separate modes of arresting the yarn after it has been pulled off the spool. Thus if the finger is timed to move radially inwardly prior to all the yarn being removed from the spool the finger 20 itself will arrest the yarn. If the finger 20 is timed ' to move radially inwardly after all the yarn wrapped onto the spool by arm 17 has been pulled off the spool, then the yarn will be arrested by the arm 17. It is envisaged that in certain instances this second mode of operation will be preferred as it does not bring the yarn to an abrupt stop as does the first mode of arresting the yarn. In this respect when the yarn is initially stopped by arm 17, the arm 17 is rotating to unwind yarn from the supply coil 28 and so this yarn is drawn from the arm 17 by the air jet nozzle 22 at a rate determined by the speed of movement of the arm 17 until the arm passes the stop finger 20 when the yarn will then be completely arrested by the stop and continued movement of the arm 17 causes the yarn to be wrapped about the spool. Thus the second mode provides two distinct stages in arresting yarn being pulled off the spool. By suitably adjusting the rotary position of the arm 17 to the stop finger 20 and/or the timing of moving the finger 20 radially inwards it is possible to adjust the length of yarn etered out at a controlled rate by the arm 17 to a desired value. By way of example a specific embodiment of the present invention is described below with reference to Figures 2 and 3. In these Figures parts corresponding to similar parts in Figure 1 have been designated by the same reference numerals. In Figure 2, the spool 12 is made up of individual segments 30 (only one of which is shown for the purposes of clarity) . The segments 3ardly so as to alter the effective diameter of the spool 12. siiBSTmr * ώ SHEET __0Λ1PI .- WIPO The annular boss 34 houses a bearing 37 which rotatably receives a shaft 40 from which arms 14 and 17 radially project. The annular boss 34 also includes a plurality of magnets 44 spaced about its circumference which co-operate with magnets 45 received in a fixed support 46 of the device 10. Magnets 44 and 45 attract one another so that annular boss 34 and accordingly spool 12 remain stationary despite rotation of shaft 40. The shaft 40 is also mounted in bearings 50 housed in support 46. The shaft 40 has a central bore 40a_ which communicates with the internal bore 14a_ of arm 14 to provide a passageway for yarn 16. Air ducts 53 are provided to enable pressurised air to be supplied to bore 40a_ to enable threading of yarn 16 through bores 40a_ and 14a_. Shaft 40 is provided with a pinion gear 40b which meshes with gear 55 mounted on a drive shaft 56 of the loom. The stop finger 20 is mounted on a support 60 which is pivotally mounted on a spindle 61. The spindle 61 is mounted in a support 62 which in turn is pivotally mounted on a spindle 63. Spindles 61 and 63 are perpendicular to one another so that the finger 20 may be moved axially along the spool and also moved radially inwardly or outwardly relative to the spool. Such movement of the finger 20 is achieved by a pair of cams 67 which co-operate with a pair of cam followers 68 mounted on support 60. The cams 67 are shaped so that at two circumferential locations they have the same profile so as to move the finger radially inwardly or radially outwardly and at other times a different profile so as to cause the support to pivot about spindle 63 and so move the finger 20 axially along the spool whilst it is maintained in either a radially innermost or radially outermost position. As seen in Figure 2 the ridge 26 has an inclined face 26a_ facing the terminal end of the spool 12. The purpose of the inclined face 26a_ is to encourage yarn wrapped about the spool 12 by the arm 17 to move axially along the spool to avoid overlapping of the yarn during winding. The rate of axial movement of finger 20 is arranged to be similar to the axial movement of the yarn 16 along the spool. A similar inclined face 12a, is provided at location 24 for co-operation with arm 14.

Claims: CLAIMS 1. A yarn metering device including a stationary spool, a yarn supply arm for wrapping yarn onto a storage region of the spool, a . yarn guide arm for simultaneously transferring yarn from the storage region and wrapping it onto a discharge region of the spool and stop means co-operable with the discharge region of the spool for permitting yarn wrapped on the discharge region to be pulled axially off the spool after a predetermined quantity of yarn has been wrapped onto the discharge region. 2. A yarn metering device according to Claim 1 wherein the stop means includes a finger movable radially relative to the spool between a first position and a second position for respectively arresting or releasing yarn wrapped on the discharge region. 3. A yarn metering device according to Claim 2 wherein the finger is arranged to move from its second position to its first position before all yarn is pulled off from the discharge region. 4. A yarn metering device according to Claim 2 wherein the finger is arranged to move from its second position to its first position after all yarn is pulled off from the discharge region. 5. A yarn metering device according to any preceding claim wherein the storage and discharge regions are separated by an annular ridge. 6. A yarn metering device according to Claim 5 wherein the ridge has an inclined face extending toward the discharge end of the spool so that yarn wrapped onto the inclined face is _ OMPI encpuraged to move axially along the spool towards its discharge end. 7. A yarn metering device according to any preceding claim wherein the yarn supply arm and the yarn guide arm are diametrically opposed and mounted on a common shaft for rotation in unison. 8. A yarn metering device according to Claim 7 wherein the shaft is rotatably mounted in a housing and the spool rotatably receives the shaft, the spool and housing having co-operable magnetic poles which restrain the spool from rotating. 9. A yarn metering device according to any preceding claim wherein the spool is composed of a plurality of segments which are radially movable for adjusting the diameter of the spool.

Inventors: GRIFFITH JOHN DALTON, GRIFFITH, JOHN, DALTON
Applicants: BONAS MACHINE CO, BONAS MACHINE COMPANY LIMITED
Application year: 1982
Main classification: B65H51
IPC codes: B65H51, D03D47