GB2131055A - Weft yarn metering apparatus - Google Patents

Abstract

A weft yarn measuring apparatus comprises clamps 11, 12 and a belt 20 with a projection 23. With clamp 11 open and clamp 12 closed the projection 23 rises along path A until it engages the weft 30 and draws it into a loop as the projection travels along path B. At point C clamp 12 opens and clamp 11 closes so that as projection 23 descends along path D the weft loop may be picked by a jet nozzle. A weft selector is disclosed wherein selected guides present their wefts to the projection 23. <IMAGE>

Description

SPECIFICATION Weft yarn metering apparatus The present invention relates to a weft yarn metering apparatus for a weaving loom, in particular a weaving loom utilising fluid means for inserting the weft yarn.

A weft yarn metering apparatus for use with a fluid jet loom needs to operate at high speeds and yet accurately and reliably meter out the same length of weft yarn for each pick of the loom. It is also highly desirable than the metering apparatus be capable of weft yarn selection so that different weft yarns can be inserted during the weaving process.

It is a general aim of the present invention to provide an apparatus which is able to fulfill the above requirements.

According to one aspect of the present invention there is provided a weft yarn metering apparatus including guide means for guiding the weft yarn along a predetermined path, reciprocally movable yarn engaging means whose reciprocal path of movement intersects said predetermined path so that said yarn engaging means can engage yarn extending along said predetermined path to form a loop, a first clamp means positioned to engage the weft yarn at a location upstream of said yarn engaging means and a second clamp means positioned to engage the weft yarn at a location downstream of said yarn engaging means, the first and second clamps operating alternatively to clamp said yarn.

Various aspects of the present invention are hereinafter described with reference to the accompanying drawings, in which: Figure 1 is a schematic illustration of a metering apparatus according to the present invention: Figure 2 is a more detailed end view of an apparatus according to the present invention; Figure 3 is a side view of the apparatus shown in Figure 2; Figure 4 is a plan view of the apparatus shown in Figure 2; and Figure 5 is a part view taken in the direction of arrow A.

Referring initially to Figure 1 there is shown a metering apparatus 10 which includes a pair of clamps 11, 12 and a yarn engaging means 16 located between the clamps 11, 12. The yarn engaging means 1 6 includes a continuous belt or chain 20 extending about pulleys 21, 22 and a projection 23 mounted on the belt 20. Weft yarn 30 is illustrated as extending from a yarn package 31 to an air jet nozzle 40 via a yarn feeder 32 and the metering apparatus 10. The yarn feeder 32 is optional but desirable as it draws yarn from the package 31 and stores the yarn in a relaxed condition until it is drawn therefrom by the metering apparatus.

The yarn 30 in passing through the metering apparatus extends through clamp 11, past the yarn engaging means 16 and through clamp 12.

The passage 30a (indicated by a dotted line) of the yarn 30 between clamps 11, 12 is arranged to intersect with the path of travel of the projection 23.

The path of travel of the projection 23 is arranged to extend above and below said passage of yarn 30.

In operation, when the projection 23 is located below said passage of yarn 30, i.e. is located somewhere along its path of travel A, clamp 1 2 is closed and clamp 11 is opened so that during the projection's 23 travel along its path B the yarn 30 is drawn into a loop 30b which attains a maximum size when projection 23a reaches its highest point C above said passage 30a. The size of the loop 30b is predetermined and corresponds to the amount of yarn 30 to be metered out.

When projection 23 reaches point C the clamps 11, 12 are operated so that clamp 11 closes and clamp 12 opens. Simultaneously, air jet nozzle 40 is actuated to shoot yarn 30 across the warp sheet. Accordingly as projection 23 descends along path D from point C to said passage 30a yarn stored in the loop 30a is drawn out by the nozzle 40 and the rate of which the yarn 30 is shot into the warp shed is determined by the rate of descent of the projection 23. When projection 23 passes beneath passage 30a the yarn 30 is held taut between clamp 11 and nozzle 40 and so the timing of operating clamp 11 to open and clamp 12 to close after weft insertion is not critical.

A more specific illustration of the present invention is hereinafter described with reference to Figures 2 to 4 which further illustrates incorporation of a weft selection capability. In the following parts corresponding to parts illustrated in Figure 1 have been designated by the same reference numerals.

In the embodiment shown in Figures 2 to 4 four weft yarns 1 5a, 1 5b, 1 5c, and 1 5d are fed through the metering apparatus 1 0. These yarns are guided across the weft yarn engaging means 16 by guide eye assemblies 50, 51. As shown, guide eye assembly 50 is located on the downstream side of clamp 11 and guide eye assembly 51 is located on the upstream side of clamp 12. Each guide assembly 50, 51 includes individual guide eyes 52, 53 respectively for each yarn. The guide eyes 52 are each located at the terminal end of a piston rod 55 so that each guide eye 52 may be moved toward or away from the path of travel of the projection 23.This is illustrated in Figure 4 wherein the guide eye 52 for yarn 15a has been moved toward the yarn engagement means 16 so that yarn 15a lies on a predetermined path (equivalent to said passage 30a in Figure 1). Accordingly when projection 23 moves along its path of travel B yarn 1 5a will be drawn from its respective yarn package to form a loop. Conveniently the piston rods 55 are pneumaticaliy operated and are arranged to be operated to extend or retract when the projection 23 is located on its path of travel A.

Preferably the piston rods are angled so that when each piston rod is extended each eye comes to the same position. This is illustrated in Figure 5 wherein each of the piston rods 55 are shown as being extendable to a common point 55a.

The clamps 11 and 12 are both mechanically operated and interconnected so as to open or close simultaneously but out of phase, i.e. one clamp opens and the other clamp closes. Each clamp includes a movable jaw 60 which co-operates with a fixed jaw 61.

The movable jaw 60 is mounted on a rotatable support 62 which is operated by a push rod 63a for clamp 11 and a push rod 63b for clamp 12.

Both push rods 63a, 63b are pivotaily connected to a lever 64 which is deflected by a cam 65.

The movable jaw 60 co-operates with the fixed jaw 61 to trap or release all the weft yarns simultaneously. Conveniently the movable jaw 60 is formed from a group of resilient strips, one strip for each yarn. The strips may be formed for example from spring steel. The fixed jaw 61 is conveniently provided with guide eyes 66 for positioning the yarns for co-operation with specific strips. The rotatable support 62 is preferably acted upon by a torsion spring 67 which serves to bias the movable jaw 60 into contact with the fixed jaw 61.

In order to thread weft through the clamp, it may be opened by rotating knob 100.

The clamp 11 and guide eye assembly 50 are arranged as a common unit which is mounted on an elongate support 70. The support 70 is slidably received on a bracket 71 and the support 70 is restrained from slidable movement by a bolt 73.

Accordingly the height of the clamp 11 and guide assembly 50 may be adjusted enabling the size of the loop created by the projection 23 to be adjusted for all the weft yarns. In order to enabie clamp 11 to rise and fall the rod 74 is slidably mounted at the fulcrum of the arm 63c but rotatably fixed.

The guide eye assembly 51 includes a group of individual guide eyes 51 a each of which is located on a slide 51 b which is slidably attached to a support bracket 80. Each slide 51 b is provided with a pair of bolts 81 which pass through elongate apertures 82 formed in the support bracket 80. Accordingly each slide 51 b may be moved longitudinally and locked in position by bolts 81. The position of each eye 51 a can therefore be adjusted to ensure that the size of loop created in each yarn is the same thereby ensuring that the amount of yarn metered for each yarn is the same.

The nozzle assembly 40 to which the yarns 1 5 are fed includes a jet nozzle 80 for each yarn. The nozzles 80 are arranged in a group and positioned so that terminal ends of the nozzles directed to a common point which in use coincides with the entrance to the weft guide channel (not shown).

The air supply to the nozzle 80 is arranged so that a low pressure stream of air is continuously supplied thereto so that yarn extending between each nozzle and clamp 12 is maintained under tension.

The continuous belt 20 is driven from the main drive shaft 90 via pulleys 91 and 92 which are connected by a timing belt 93. The belt 20 is conveniently a toothed belt having internally extending teeth so that timing of the position of projection 23 can be determined.

The drive ratios are arranged such that projection 23 completes one complete cycle of movement for each weft insertion. If the inserted length of weft requires to be changed to a greater extent than moving clamp unit 11 allows, then the length of belt 20 may be altered, pulley 22 moved to suit, and the drive ratio of the belt changed so that projection 23 stili completes the cycle every weft insertion.

Claims (3)

1. A weft yarn metering apparatus including guide means for guiding the weft yarn along a predetermined path, reciprocally movable yarn engaging means whose reciprocal path of movement intersects said predetermined path so that said yarn engaging means can engage yarn extending along said predetermined path to form a loop, a first clamp means positioned to engage the weft yarn at a location upstream of said yarn engaging means and a second clamp means positioned to engage the weft yarn at a location downstream of said yarn engaging means, the first and second clamps operating alternatively to clamp said yarn.

2. A weft yarn metering apparatus according to Claim 1 wherein a plurality of yarns are provided each of which is guided through a respective retractable guide, each guide being capable of moving its associated yarn onto said predetermined path for engagement with said yarn engaging means.

3. A weft yarn metering apparatus substantially as described with reference to and as illustrated in any of the accompanying drawings.