US3908710A | 1975-09-30 | |||
GB2065178A | 1981-06-24 | |||
GB1085458A | 1967-10-04 |
1. | A yarn end holding device for a loom, the 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 beatup. |
2. | A device according to Claim 1 wherein the clamp means is arranged to cooperate with the reed of the loom in order to remove slack from the yarn during beatup. |
3. | A device according to Claim 1 or 2 wherein the clamp means includes a fixed jaw and a movable jaw timed to open and close the clamp means in coordination with the beatup sequence of the loom, at least one of said jaws being resilient. |
4. | A device according to Claim 1, 2 or 3 wherein the channel has an elongate mouth positioned to receive yarn and weft insertion fluid carrying said yarn, the mouth extending along the warp sheet and said clamp means being positioned adjacent to said mouth. |
5. | A device according to Claim 1, 2 , 3 or 4 wherein said fluid flow along the channel is created or assisted by suction means arranged to create a suction effect at the mouth of said channel. |
6. | A device according to Claim 5 wherein the suction means includes means for introducing a high pressure fluid flow along the channel at a location downstream from said mouth. |
7. | A device according to any preceding claim wherein cutting means are provided for severing the held yarn ends from the warp sheet. |
8. | A device according to Claim 7 where dependent on Claim 3 wherein the cutting means comprises a cutting blade mounted on the movable jaw of said clamping means. |
9. | A yarn end holding device substantially as described with reference to any of the accompanying drawings. |
10. | A weaving loom including a yarn end holding device according to any preceding claim. |
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.
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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 22_a which is permitted to enter the interior of housing block 17 via an annular gap 221D. The mouth 22C to pipe 22 is radiussed so that the pressurised air exiting from gap 2213 clings to the internal wall of tube 22 and so exits therealong creating a vacuum in channel 16.
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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 5 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. 10 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 15 into the narrow mouth portion 18b_ the clamp is operated by cam 35 to 15 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 20 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 25 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 321D. A rigid slide member (not shown) may be located above body portion 321D to partially overlap it to define a flexing - 30 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.
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