GB2282610A - Yarn feed apparatus for loom - Google Patents

Abstract

A yarn feed apparatus 10 comprises an accumulator (16) for storing profiled yarn fed from a yarn feed package (11) and subsequently relaying the yarn to a loom. The line of feed from the feed passage (11) to the accumulator is substantially in the same plane as the line of feed from the accumulator (16) to the loom so as to prevent twisting of the yarn between the feed package and loom. In the embodiment shown the accumulator comprises two plates, e.g. of glass, spaced by a distance only slightly greater than the yarn thickness. The plates may be curved. In other embodiments the yarn may be stored between two travelling belts of napped material, over sets of separable rollers, in storage tubes or slots into which the yarn is forced by air jets or by hooks, on an open spoked wheel or round a spindle and parallel movable bar. <IMAGE>

Description

YARN FEED APPARATUS This invention relates to a yarn feed apparatus and particularly, but not exclusively to a yarn feed apparatus for feeding profiled weft yarn to a loom for making papermakers' fabrics such as dryer fabrics.

The term "profiled yarn" used herein is used to describe yarn which is symmetrical in cross section apart from yarns having a round cross-section. Typical profiled yarns would include flat yarns or yarns having a triangular cross section.

Papermakers' dryer fabrics are relatively simple to weave since the warp in the loom extends in the running direction of the paper machine. Although shuttles are used they are empty. The weft yarn is fed from a large package, end-over, onto a temporary storage accumulator. The accumulator amasses slightly more than the cross loom width equivalent of yarn before the next picking action. The shuttle is equipped with a gripping device which snatches the yarn from the accumulator and drags it across the loom on a sley. The yarn at the feed side is then severed so that each pick is represented by a discontinuous yarn. Known accumulators are conventionally used to store round monofilament yarn. In use the yarn is removed from the bobbin by pulling the yarn in the same direction as the axis of rotation of the bobbin. This results in twisting of the yarn.

The present invention seeks to provide a yarn feed apparatus which can receive yarn from a feed package and feed the yarn to the loom where it is deposed between the warp yarns at the shed without twisting the yarn.

This is particularly important when the yarn is a profiled yarn rather than a monofilament yarn which is round in cross-section.

According to one aspect of the invention there is provided a method of feeding profiled yarn from a yard feed package to a loom comprising the steps of feeding the yarn from the feed package to an accumulator, storing a portion of yarn in the accumulator, taking said portion of yarn from the accumulator to the loom, characterised in that the line of feed from the feed package to the accumulator is in the same general direction as the line of feed from the accumulator to the loom so as to prevent twisting of the yarn between the feed package and the loom.

According to a second aspect of the invention there is provided a yarn feed apparatus comprising an accumulator for storing profiled yarn fed from a yarn feed package and subsequently relaying the yarn to a loom, characterised in that the line of feed from the feed package to the accumulator is in the same general direction as the line of feed from the accumulator to the loom so as to prevent twisting of the yarn between the feed package and the loom.

The invention is particularly advantageous when used with flat yarn having an aspect ratio of at least 1.5:1.

The yarn may be stored between spaced apart plates, the spacing of the walls generally being slightly greater than the width of the yarn. The spacing of the plates may be adjustable in order to accommodate different yarn widths. Friction between the plates and the yarn may be reduced by providing protrusions on the plates and/or highly polished plates may be used. The plates may be parallel, curved or urged into a convex shape.

Alternatively the accumulator may comprise spaced apart movable continuous belts.

Alternatively the yarn may be urged through holes, tubes or the like in the accumulator. The yarn may be urged via pressure fluid operable rams, gas jets or pulled into the holes, tubes or the like via hooks.

As another alternative the yarn may be fed over a rotatable member such as open spoked wheel or over a bobbin and bar, the bar being movable relative to the bobbin.

In order that the present invention may be more readily understood specific embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings in which: Fig. 1 shows a yarn feed apparatus in accordance with the present invention; Figs.2 and 3 show variations in the arrangements of the plates of the apparatus of Fig.1; Fig.4 shows a second yarn feed apparatus in accordance with the invention; Fig.5 shows a third yarn feed apparatus in accordance with the invention; Fig.6 shows a fourth yarn feed apparatus in accordance with the invention; Fig.7 shows a fifth yarn feed apparatus in accordance with the invention; Fig.8 shows a sixth yarn feed apparatus in accordance with the invention;; Fig.9 shows a seventh yarn feed apparatus in accordance with the invention; and Fig.10 shows the apparatus of Fig.9 having accumulated the required length of yarn.

Referring to Fig.1 a yarn feed apparatus 10 is operative to feed, without twisting, a profiled yarn such as flat yarn from a yarn package 11 to the shuttle of a loom. The yarn package 11, in this example, is a 250mm DIN spool containing, for example polyester yarn of dimensions 0.64mm x 0.38mm (an approximate 2:1 aspect ratio).

The yarn 12 is received between a pair of rubber coated yarn feed rollers 13,14 which pull the yarn 12 from the bobbin 11 and urge the yarn 12 through a precisely fashioned slotted guide tube 15. The guide tube 15 is located at the top of an accumulator body 16 which comprises a glass walled chamber. The two walls of the chamber which extend from left to right, as illustrated, are spaced apart by a distance minutely greater (say about + O.lmm) than the length of the yarn's largest dimension, i.e. 0.64mm. The yarn slacks in the accumulator without twisting. Air jets 17 direct compressed air towards the yarn in the accumulator body in order to compress the yarn towards the base of the accumulator body.

The yarn 12 is fed out of the accumulator body 16 via an exit 18. Here the yarn is snatched by the shuttle and moved across the loom. The apparatus disposes the yarn freely, speedily and without twisting.

The yarn is stored in the accumulator body in a wave like manner. If the yarn encounters sufficient friction from the glass plates the amplitude of the stored yarn tends to decrease with time. Thus the yarn towards the base of the accumulator tends to extend almost entirely across the base of the accumulator whereas the yarn towards the top of the accumulator may only extend along a short length of the accumulator. In order to address this problem the invention provides a number of ways of reducing contact friction. The plates may have raised areas such as by providing ribs on the glass plates. Alternatively one or both of the glass plates could be replaced by machined metal plates as machinery would yield micro furrows in the surface.

However, if both plates were replaced with metal plates this would restrict visibility unless a window was provided in one of the plates. The glass plates of Fig.1 could be replaced by a close packed assembly of glass or metal rods which would be arranged to make up parallel sheets.

Figs.2 and 3 show two further ways of reducing contact friction. The plate arrangement of Fig.2 creates a pressure release in the gap between the ends of the plates by moving them into a slight convex shape.

This may be achieved by providing wedges 19 between the edges of the plates 20 and/or by exerting an inwardly directed force at or adjacent the centre of each of the plates. The plate arrangement of Fig.3 shows spaced apart curved plates 21. This arrangement takes account of the tendency of the folded yarn to twist slightly, while at the same time controlling this. The spacing "X" of the plates towards the edges is larger than the spacing "Y" at the centre of the plates.

Further possible modifications to the apparatus of Fig.1 include a yarn feed which reciprocates to deliver yarn across the full plate width. Furthermore a trailing arm could be used to effect better yarn distribution within the plate zone.

The apparatus of Fig.4 shows a further yarn feed apparatus 22 in accordance with the invention. This apparatus comprises an accumulator which is made from two spaced apart continuous belts 23,24 made from a material bearing a fibrous nap. The belts may be run over feed rollers 25 when required. In use the belts 23,24 would advance between picks in the direction of arrows "A" so as to build up the requisite yarn volume.

The apparatus would further comprise side walls (not shown), a slot being provided towards the base of one of the side walls through which the yarn would be fed. At the moment of picking the yarn would be drawn out from the slit, preferably with the belt system in a temporary static state.

Fig.5 shows a further accumulator in accordance with the present invention. The accumulator comprises a row of stationary bodies and the ends of pneumatically operated cylinder and ram arrangements. The row of rams is movable relative to the stationary bodies. Yarn is fed from an accumulator below a first roller of the first row over the first roller of the second row and so forth as illustrated. After passing over the last roller in the second movable row the yarn passes out to the loom. A release clamp arrangement is provided as the yarn passes to the loom. In use a pick of yarn can be accumulated by moving the second row of rollers from a first rest position 'A' away from the first row to a second storage position 'B' as shown in Fig.5.Shelves are provided in between the paths of travel of the movable rollers In use, at the interval between picking, the yarn is temporarily held in position by the clamp. The second row of plungers push the yarn whilst drawing the yarn from a bobbin between the shelves. The plungers can then retract leaving the requisite length of yarn available from the shuttle.

Fig.6 shows a variant of the apparatus of Fig.5 in which air jets replace the pneumatic piston cylinder apparatus. The yarn is forced into storage tubes by air from the jets, ready for withdrawal by the gripper shuttle.

Fig.7 shows a further yarn feed apparatus. Yarn is fed from the feed package across a table to the loom.

A series of spaced apart slots are provided in the table. The yarn may be drawn down through the slots by hooks so as to accumulate sufficient yarn for a pick.

At the picking stage the hooks would rise above the plane of the table to allow release of the yarn. The hooks subsequently descend back below the table so as to accumulate sufficient yarn for another pick.

Referring to Fig.8 a further yarn feed apparatus comprises an open spoked wheel. Yarn is stored over and between the wheel spokes. The yarn is then fed to the loom for the gripper offering virtually nil resistance.

A further possibility for storing yarn would be to use the essential principle associated with link spiral manufacture. Regulation of the package to the flyer speed would be necessary to avoid introducing twist.

Referring to Figs.9 and 10 yarn is stored on a bobbin, which is supported on a free spindle. About six lengths of yarn are taken off the supply package and fed around a bar which is attached to two pneumatic or hydraulic pistons. As the distance between the bobbin and bar is increased yarn will be paid out from the bobbin leaving an open skein.

If the rod is light in weight when the gripper snatches the yarn it will be dragged off the assembly thereby raising the rods to its initial starting point ready for the repeat cycle.

It is to be understood that the above described embodiment has been described by way of illustration only. Many modifications and variations are possible.

Claims (16)

1. A yarn feed apparatus comprising an accumulator for storing profiled yarn fed from a yarn feed package and subsequently relaying the yarn to a loom, characterised in that the line of feed from the feed package to the accumulator is substantially in the same plane as the line of feed from the accumulator to the loom so as to prevent twisting of the yarn between the feed package and the loom.

2. A yarn feed apparatus as claimed in claim 1, characterised in that the yarn is a flat yarn having an aspect ratio of at least 1.5:1.

3. A yarn feed apparatus as claimed in claim 1, characterised in that the yarn is triangular in cross section.

4. A yarn feed apparatus as claimed in any of claims 1 to 3, wherein the yarn is stored in the accumulator between spaced apart plates.

5. A yarn feed apparatus as claimed in claim 4, wherein the spacing between the said plates is adjustable.

6. A yarn feed apparatus as claimed in claim 4 or claim 5, wherein the said plates are flat and are arranged in a parallel disposition.

7. A yarn feed apparatus as claimed in claim 4 or claim 5, wherein the said plates are curved.

8. A yarn feed apparatus as claimed in any of claims 1 to 3, wherein the yarn is stored in the accumulator between movable continuous belts.

9. A yarn feed apparatus as claimed in any of claims 1 to 3, wherein the yarn is urged into holes or tubes.

10. A yarn feed apparatus as claimed in claim 9, wherein the yarn is urged into the holes or tubes by pressure fluid operable rams.

11. A yarn feed apparatus as claimed in claim 9, wherein the yarn is urged into the holes or tubes by gas jets.

12. A yarn feed apparatus as claimed in claim 9, wherein the yarn is pulled into the holes or tubes.

13. A yarn feed apparatus as claimed in any of claims 1 to 3, wherein the yarn is stored in the accumulator on a rotatable member and a bar, the bar being movable relative to the rotatable member.

14. A yarn feed apparatus as claimed in claim 13, wherein the rotatable member comprises an open spoked wheel.

15. A method of feeding profiled yarn from a yarn feed package to a loom comprising the steps of feeding the yarn from the feed package to an accumulator, storing a portion of yarn in the accumulator, taking said portion of yarn from the accumulator to the loom, characterised in that the line of feed from the feed package to the accumulator is substantially in the same plane as the line of feed from the accumulator to the loom so as to prevent twisting of the yarn between the feed package and the loom.

16. A yarn feed apparatus substantially as defined herein with reference to any of Figs. 1 to 10.