YARN HOLDING DEVICE

YARN HOLDING DEVICE

The present invention relates to a yarn holding device particularly for use in a loom having a fluid weft insertion.

In a loom employing means for inserting a weft yarn by means of a fluid, the weft yarn is shot across the warp sheet by the fluid and it is necessary to hold the free end of the weft yarn on the far side of the warp sheet opposite to insertion during beat up in order to create the necessary tension in the weft yarn. This is achieved conventionally by either weaving the free end into a dummy selvedge which is subsequently removed or by pulling and holding the free end in a suction device by means of a frictional force created by a flow of fluid. In the latter case a sufficient length of weft yarn must be located in the suction device in order to create the necessary amount of frictional force for pulling and holding the weft yarn under a desired tension.

In both conventional methods the amount of weft yarn used is escessive and therefore adds a significant cost to the weaving of yarns using fluid insertion means.

It is a general aim of the present invention to provide a device for positively holding a relatively short free end of weft yarn thereby reducing the amount of weft yarn required.

According to one aspect of the present invention there is provided a yarn end holding device including a fluid channel along which a fluid flow is directed to draw the yarn end into the channel and clamp means positioned to receive the yarn end and hold it during beat up.

Preferably the clamp means co-operates with the beat up reed of the loom to tension the weft yarn during beat up. The clamp means advantageously includes a fixed jaw which is resilient and a movable jaw timed to open and close the clamp means in co-ordination with the beat up sequence of the loom. The degree of resilience of the resilient jaw is conveniently adjustable to vary the tension created in the weft yarn during beat up. According to another aspect of the invention there is provided a loom including a holding device as defined above.

Various aspects of the present invention are hereinafter described with reference to the accompanying drawings, in which:

Figure 1 is an end view of a device according to the present invention shown in situ on a loom, the device being viewed in the direction of weft insertion;

Figure 2 is a plan view of the device as shown in Figure 1;

Figure 3 is a side view of part of the device shown in Figure 1;

Figure 4 is a schematic plan view similar to Figure 2 illustrating beat up. A holding device 10 is located on a loom frame adjacent to the far end 12 of the warp sheet 14 opposite to the side whereat the weft yarn 15 is inserted.

The device 10 includes a channel 16 defined within a housing block 17, the channel 16 having an elongate mouth 18 facing the warp sheet. The length of mouth 18 is such as to extend along the warp sheet 14 for approximately the distance of travel of the reed 20 between weft insertion and beat up.

The mouth 18 has a relatively wide portion 18a positioned so as to receive air being directed across the warp sheet 14 for insertion of the weft yarn. Air entering mouth 18 exits through a pipe 22 so that a flow of air is directed along the channel so that the free end 15a of the inserted weft yarn 15 enters mouth 18 through mouth portion 18a. and remains there due to the flow of air. If necessary, the flow of air through channel 16 may be supplemented or created by applying suction at the mouth 18 of the channel. This helps to position the yam within the channel and may be achieved by feeding pressured air to the annular groove 22a which is permitted to enter the interior of housing block 17 via an annular gap 22b. The mouth 22C to pipe 22 is radiussed so that the pressurised air exiting from gap 22b clings to the internal wall of tube 22 and so exits therealong creating a vacuum in channel 16. After insertion of the weft yarn, the beat up motion begins wherein the reed 20 begins to move towards the right as viewed in Figure 1. Initially the reed 20 engages weft yarn 15 and moves it towards the weave so that the free end 15a is caused to move along the mouth 18 towards a relatively narrow mouth portion 18b. Advantageously a photo-sensor 26 is located adjacent mouth 18 in the path of travel of free end 15a so that if the free end 15a is not detected after insertion the loom is stopped. A clamp 30 is located adjacent the narrow mouth portion 18b and includes a stationary resilient jaw 32 and a movable jaw 33 which is conveniently operated via a cam 35 and cam follower 36. As the reed 20 moves the yarn end 15a into the narrow mouth portion 18b the clamp is operated by cam 35 to grip the yarn end 15a between jaws 32 and 33.

Further movement of the yarn end 15a by the reed 20 is resisted by the clamp 30 and as viewed in Figure 4, the yarn end 15a beings to trail behind the remainder of yarn 15 as it is moved by the reed 20 and consequently the yarn 15 is tensioned. Due to the resilience of jaw 32, the yarn end 15a is permited to move in the direction of the reed 20 at a controlled rate dependent on the degree of resilience of jaw 32. Accordingly, the amount of tension created in the yarn 15 may be varied by altering the resilience of jaw 32. In the illustrated embodiment jaw 32 is formed from a thin sheet 36 of resilient material such as spring steel which is bent so as to form a jaw portion 32a depending from a support body portion 32b . A rigid slide member (not shown) may be located above body portion 32b to partially overlap it to define a flexing region between itself and jaw portion 32a and is secured to the housing block 17 by a bolt (not shown) to secure the body portion in position. The resilience of jaw portion 32a may therefore be altered by varying the extent of the flexing region. Advantageously, the free ends 15a after beat up may be trimmed from the weave selvedge by mounting a cutter blade 48 on jaw 33 and a co-operating blade 49 on housing 17 so that the ends are trimmed each time the jaw 33 is moved to engage jaw 32.