GB2135342A - Shuttleless looms - Google Patents

Abstract

A shuttleless loom in which weft is inserted into the shed by means of a reciprocating weft inserter 4 wherein guide means 20,20' are located in the weft yarn path between the weft supply source 18,18' and the weft inserter, such as to cause the weft inserter to withdraw an "excess" length of weft from the weft supply source during "reverse" movement of the inserter from the shed, a weft engaging member 50 being provided to engage weft yarn extending from the front of the weft inserter when it is withdrawn from the shed so as to cause the said "excess" length of weft to be held during the first part of the subsequent forward movement of the inserter into the shed, the weft engaging member being operable to disengage or release the weft during a subsequent part of the forward movement of the inserter to reduce pull on the yarn during insertion. <IMAGE>

Description

SPECIFICATION Improvements in and relating to shuttleless looms This invention relatesto shuttleless iooms, that is to say, looms in which the weft yarn, from a supply source normally a stationary package outside the shed, is inserted into the warp shed by means of a weft inserter which is reciprocated into and out ofthe shed.

The weft inserter may be carried on, or be in the form of, a rigid rod, or alternatively, it may be carried on a flexible tape or band and in either case the most common form of drive comprises a toothed driving wheel which engages a corresponding row of teeth on the inserter rod of flexible tape. In the case of the flexible band ortape the teeth are defined bythe spaces between a row of perforations. Such a loom will hereafter be referred to as a "shuttleless loom of the type described".

In orderto produce the required reciprocation ofthe inserter, the driving wheel must revolve,firstin one direction and then the other and one suitable form of mechanism for producing this result comprises a relatively small pinion which is fixed to the same shaft as the driving wheel and which meshes with a pivoted toothed sectorwhich is caused to reciprocate about its pivot. The sector may reciprocate through an angle of, for example, ninety degrees, producing several revolutions ofthe pinion for each stroke, thus leading to a corresponding number of revolutions of the driving wheel and corresponding reciprocatory stroke ofthe weft inserter.

The reciprocation of the toothed sector may, in its turn, be produced by a rotary crank or eccentric having a connecting rod of which the other end is connected to the toothed sector. Each revolution ofthe crank or eccentricthus produces a cycle of reciprocation of the sector and hencethedrivingwheel and weft inserter.

As in any such drive the rotary motion of the crank or eccentric causes the connecting rod and hence the toothed sector and inserters to decelerate towards the end of each stroke, to dwell instantaneously at the reversal point and then accelerate again up to its maximum velocity at mid-stroke. In orderthat such inserter drives and cloth beat-up mechanisms are as uncomplicated as is possible,the inserter must withdraw beyond the side of the cloth over a sufficient length to provide enough timeforthe reed to beat-up the cloth and withdraw again before the inserter re-enters the shed on the next forward stroke. As a result an excess length of weft thread will extend from the natural bound side ofthe cloth to the front of the inserter and this excess must be taken up on the next forward stroke before weft again commences to be taken from the supply source.This can result in two notable related problems. Firstly if, when the inserter requires weftfrom the supply package, it is moving at or about its maximum velocity, the abrupt pull on the yarn causes itto whip and also subjects itto instantaneous high centrifugalforces such that with poorer quality yarns, an unacceptable level of weft breaks occur. Secondly, when the slack is exhausted and the closed end of the weft hairpin comes up against the side ofthe cloth from which it extends, the abrupttug can in itself breakweakyarns. Furthermore it can cause uneven cloth width by pulling the edge inwardly unless additional mechanical measures are incorporated to restain movement ofthe cloth.This, in turn, removes the resilience of the cloth and further aggravates the occurance of end breaks.

This problem is very significantly aggravated when weaving double shots as the yarn pulled from the package in any one cycle mustbetwicethe length of the shed and "slaving" ofthe weft occurs at the nose oftheinserter. lnordertoovercomethisproblem expensive mechanical and pneumatic pre-feed devices have been developed which are positioned intermediate the supply source and the weft inserter and which measure and store in a tensionless or substantially tensionless state, the length of yard required for each weft insertion cycle.Alternatively, a compound articulated linkage system has been pivotally attached at one end to the rear of the inserter and at the other end to the weft supply source so as to form an elbow type extension ofthe inserter and hence maintain a constant length of weft between the supply packageandtheinserteratall positions of the latter thus preventing the formation of excess yarn. However, such constructions are cumbersome and restrict the speed ofthe inserter.

The object ofthe present invention is to obviate the aforesaid difficulties without the requirementto resort to sophisticated and expensive pre-feed mechanisms or speed restrictive mechanisms.

The invention applies particularly but not exclusivelyto loomsforjuteand like yarns, having at least one pairof spaced apartwarp sheds and insertermechan- ism particularto each shed but with a common drive mechanism. On such loomstheexpenseofsophisti- cated pre-feed mechanisms for each weft yarn would betwo-fold and could detract from the attractiveness of this type of loom. Similarly, to incorporate an elbow type yarn path compensator on each inserter not only would add expense but would necessitate a significant increase inthewidth of the loom.However, the loom ofthe invention may have only a single warp shed but in each case the shed(s) should be relatively narrow (e.g., 33 inches) so thatthe weft may be fully inserted across the complete shed by a single inserter rather than the weft being transferred to a second inserteratthecentre ofthe shed.

Ashuttleless loom of the type described in accordance with the invention has weft guide means located in the weft yarn path between the weft supply source and the weft inserter, the relative positions of the guide means and weft inserter, being such as to cause the weft inserter to withdraw and "excess" length of weft from the weft supply source during the "reverse" movement ofthe inserter from the shed, a weft engaging member of members being provided to engage the weft extending from the front of the weft inserterwhen it iswithdrawn from theshed to cause the said excess length of weft be held, preferably in the form of a hair pin, during the first part ofthe forward movement ofthe inserter, the weft engaging member being operated to disengage or release the weft during a subsequent part ofthe forward move ment ofthe inserter.

Depending on va rious facto rs -- e.g. quality of yarn and with width of cloth the "excess" length of weft yarn which is held bythe weft engagirig member may be iong enough for the inserterto have passed through its maximum velocity phase and be decelerating before it requires to pull yarn from the supply package.

Alternatively, and preferably, the timing and positioning ofthe weft engaging member may be such as to cause the inserterto commence pulling yarn from the supply package at an early stage of its forward stroke while the yarn is still held under control by the weftengaging memberand the inserter is moving below maximum velocity. As a result, the length of excess yarn is supplemented while still held by the weft engaging member so that when released by the said member as of before the inserter reaches maximum speed, a sufficient surplus exists to enable the inserterto traverse the remainderofthe shed without having to pull anyfurtheryarn from the supply package, orto have passed through the maximum velocity phase before requiring to do so.

In either case the yarn is not subjected eitherto the severe snatch atthe supply package northe harsh braking effect againstthe side of the cloth, hence enabling poorer quality yarns to be woven at high picking speeds.

Afurtherweft engaging member may be positioned so asto be engaged by the length ofweftextending between the guide means and the inserter during the forward or insertion stroke of the inserter, the member being arranged to move to a limited extent in the general direction ofmovementoftheinserterso asto aid in supplying weftto the inserter during insertion.

For particularlyweak or irregularyarns, a rotating member may be provided in advance of the weft guide means so that the weftyarn being pulled from the supply source will engage its face. Atthose parts ofthe inserterstroke where the tension on the yarn in creases,theyarn will bite against the rotary surface, which will be driven to have a higher surface speed than that of the yarn, thus assisting its forward travel and hence reducing the strain upon it, therebyfurther minimising the incidences of weft breaks.

The weftfrom the supply package is preferablyfed to the weft inserter art a point spaced rearwardlyfrom the head ofthe inserter so that weft is withdrawn from the supply source during the later, slower, speed part ofthe reverse movement of the inserter by the inner end ortail ofthe inserterwhich end is caused to extend awayfromthe guide means by a distance which is longerthan the shortest distance between the guide means and the inserter.

In accordancewith afurtherfeatureofthe invention, a weft inserterfor use with a shuttleless loom of the type described but, which may or may not be that defined hereinbefore, comprises an elongated weft carrier with means, e.g. teeth or spaces, to mesh with cooperation drive means to reciprocate the carrier into and outfrom, the warp shed and front and rearweft guides mounted on the carrier and spaced over a part of its length.

Preferably, the front and rearweftguides are connected by a tubular memberto avoid the risk of the weft "whipping" during insertion. In fact the front and rear weft guides and tubular members are convenientlyformed as a single unit.

The carrier is preferably a flexible tape which is engaged bya driven toothed wheel or sector and the tubular member preferably lies above and substantial iy parallel with the carrier.

Thus the inserter has a head with a guide, at one end and a further guide in mounted atthe rear end, both the carrier and the guides entering the shed during use carrying theweftthread.

The invention will now befurtherdescribed by way of example with referencetothe accompanying drawings, in which: Figures 1 to 3 are diagrams illustrating an embodi mentofashuttlelessloom in accordance with the invention at three different positions ofthe weft inserters during a loom cycle; Figures 4 and 5 are similarto Figures 1 and 3 but show a slightly modified construction and illustrating the right-hand weft inserter in two further positions; Figure 6 is a plan view of the head and front part of the insertertape of an inserter in accordance with the invention chiefly for use with the loom illustrated in Figures 1 to 5; Figure 7 is a side elevation of the head illustrated in Figure 6;; Figures 8 and 9 are sections on the lines Z-Z and Y-Y of Figure 6, respectively; Figure loins a front view of the inserter of Figure 6; Figure 11 is a side elevation ofthetail end ofthe inserter of Figure 1 and illustrating part of the body thereof; Figure 12 is a plan view of Figure 11; Figure 13 is a viewsimilarto Figure 11 but showing a slightly modified construction; Figure 14 is a side view of the complete inserter but with the carriertape foreshortened; and Figures 1 SA and 1 SB are front and end views of the righthand side of a loom construction similarto that illustrated in Figures 1 to 14butalso incorporating a tension reduction mechanism.

Referring to Figures 1 and 2, weft inserters generally shown at 2 and 4 are mounted upon and carried by, a perforated tape 6 which is reciprocated by a toothed driving wheel 8 positioned mid-way between the two warp sheds generally shown at 10,12. Thetoothed wheel is driven by mechanism (not illustrated) as generally described herein before. In the position shown in Figure 1,the lefthand inserter 2 has advanced fullythrough the warp shed 10 and laid one weft leg 14 of the double pick The weft yarn 16 is ballooned over end from a stationarysupplypackage l8forthelefthandinserter, and on the way to the inserter passes through a guide member 20. The inserter2 is shown atthe point of reversal and a selvedge hook 22 atthe lefthand selvedge has pivoted into the operative position so as to engage the loop ofthe weft hair pin extending from the nose of the inserter. At the righthand side ofthe shed i.e. the natural bound selvedge, a cloth hook 24 is already hooked into the edge ofthe cloth so as to maintain the width of the cloth againstthe tension of the weft being laid, the weft being laid continuously in loops back and forth within the sheds. Atthe righthand side when the shed changes, the second leg ofthe previous pick is trapped by the changeover of the warps and loops around the edge ofthe cloth to form the natural bound selvedge and the first leg of the next double pick being fed in the new shed.

Referring to Figures 6to 12, each inserter 2,4 has a head portion 26 and a separate tail portion 28 joined to the head portion by a tubular member 30.

The head portion comprises a wear resistant end piece having a rounded nose 32 formed with a weft yarn guide eye 34 connected to the interior of the tubular member 30. The round nose prevents the weft from having to make any abrupt change of direction and the shape ofthe head portion is such that it is prevented from catching on the warp threads as the head passesthrough theshed. The underside ofthe head is connected to the front end ofthe tape 6 by rivets 36.

Thetail portion comprises in effect a rear wearresistantyarnguide eye 38 open to the interior ofthe tube30 and joined tothetape 6 at40 by a curved tail part42 so as to prevent any possibility oftheweft looping underthe insertertube.

The tubular body 30 through which the weft passes restrains thetendancy of the weft to whip about and possibly catch on the tape dueto the turbulence caused bythe high speed movement ofthe tape through the shed. The tube also acts as a braketo prevent overthrow of the weft at the point of reversal oftheinserterwhentheforward momemtumtendsto propel the weft beyond the end of the shed.

As just described, the weftfrom the supply package passes through an eye 38, atthe rear of the inserter and then along the tubular body 30 to the curved nose ofthe inserter, around the edge 32 of the nose and backto the cloth.

The right-hand inserter4 is a similarto the left-hand inserter 2 described with reference to Figures 6 to 12 and identical reference numbers are used with the addition of a primeforthe right-hand inserter.

Itwill be appreciated that although two spaced inserters2,4, are illustrated,theycould be formed as a single unitwith a continuous tubular body having a nose at each end appropriate spaced openings representing the eyes 38,38'.

Referring backto Figure 1,the right-hand inserter4 which will, of course, move as one with the left-hand inserter 2, has withdrawn fully from the right-hand shed 12 having laid the second leg 44 ofthe pick in the shed, the selvedge loop of that pick being held by the selvedge hook 46 at the right-hand side ofthe cloth. At the other side the cloth (the natural bound selvedge) hook48 is withdrawn from the cloth but will hook back into the edge as the inserter4commences its forward movement. Aweft engaging member i.e. gripper 50' catches and holds the yarn protruding from the nose 26' ofthe inserter 4. It will be observed thatthe gripper 50 which cooperates with the lefthand inserter 2, is in the open position.The shed changes and the reed 52' moves forward in the direction of the arrow to beat-up the cloth.When beat-up has been effected and the reed clear ofthecloth the drive wheel 8 reverses so as to move the tape 6 and hence the inserters 2,4, in the opposite direction,the inserter 2 to withdraw out of the shed 10 and the inserter 4 forward into the shed 12.

The front guide eye 34 is displaced to one side of the inserter head (see Figures 6 and 8) and in the inoperative position (i.e. open)thetopfingerofthe gripper 50 is positioned so thatthe inserter head on its reverse movement can pass by it. The fingerthen pivots downwardly and traps the yarn 6 against its cooperating fixed finger which lies just below the level ofthefront guide head 26 so that when the inserter reverses and commences its forward movement, the closed gripper is below the level ofthefront guide and hence the inserter can pass overthe top of it leaving the yarn held bythe gripping fingers.

Figures 2 and 3 illustrate two subsequent stages in the cycle.

In the position illustrated in Figure 2, the lefthand inserter has partially withdrawn from. and the righthand inserter has partially entered their respective sheds. The gripper 50' holds the weft to create a hair pin 54 outside the left-hand shed..ln the position illustrated in Figure 3, the inserter 2 has nearly reached the described position of the right-hand inserter4in Figure 1 and the right-hand inserter is approaching the right-hand selvedge ofthe cloth.

Referring again to Figure 1, the tail eye 38' of the inserter 4 in the fully withdrawn position extents past the guide member20' to such an extentthatthe straight line path form the guide member 20' to the inserter rear eye 38' is substantially longer than straight line vertical path from the guide member to the inserter-- i.e., the approximate length of yarn 16' extending between the guide member and the rear or rail eye ofthe inserter4will be substantially longer thanthatextending between thetwo in the position illustrated in Figure 2.

As a result, when the inserter 4 is being accelerated towardstheshedoverthefirstpartofthecycle, no yarn is being withdrawn from the supply package 18' as the insertermerelytakes uptheslack resulting from the diminishing length oftheyarn path between the guide member 20' and the rear eye 38' of the inserter.

During this part of the forward movement of the inserter, the weft is held bythe gripper 50' with the resultthatthehairpin 54 is formed between the left-hand side ofthe cloth, the gripper 50' and the nose 26' of the inserter4. Depending on the quality of the yarn and width of cloth, the gripper 50' can be timed either to release the hair pin or weft just as the slack is taken-up, as illustrated by the dotted line 50'A, or alternatively it can retain hold of the hair pin for a further part of the inserter movement, butwhile it is still moving below its maximum velocity, so as to increase the length of the hair pin before releasing it.

This latterstate is illustrated bythegripperbeing closed as at 50'B.

Forthe next part ofthe forward travel ofthe inserter as it passes through its maximum velocity phase, it takes upthe surplusweftformed by this hair pin so that no weft is withdrawn from the supply package and it isonlywhen hair pin 54 has been "used up" or "straightened out" (Figure3), by which time it is decelerating, that the weft is withdrawn from the supply package 18'. In otherwords,the relative positions of the guide members 20, 20' inserters 2, 4, and grippers 50, 50' are arranged so that the inserters have not reached and/or have passed through their maximum speed on the forward stroke and are decelerating before they commence to withdraw yarn from their respective supply packages 18,18'.On the reverse stroke this is not as critical for, as will be observedfromthedrawings, a moresevere drag will be imposed on the weft on the forward stroke when the inserter is laying the yarn in the shed since the two legs ofthe weft are virtually parallel and the yarn is turning through approximately 1 80" atthe nose ofthe inserter. On the reverse stroke when yarn is being withdrawn from the supply package by the inserter, although the yarn is doubling back overthe back eye ofthe inserter, it makes an angle with the guide member and hence drag is reduced.During a part of this reverse movement, the second leg of the weft pick already lies within the body ofthe inserter which simply leaves it behind in the shed and the rate at which the remainder is unwound from the package coupled with the angled path referred to above, does not present problems.

Aweftstop 56. 56' is positioned at the side of the shed next to the inserter drive-- i.e., atthe right-hand side of shed 10 and left-hand side of shed 12. In the construction illustrated in Figures 1,2 and 3 it remains in a fixed position and its function is to prevent the weftfrom slaving against the upper end warp yarn during the last part ofthe forward travel of the inserter.

However, in a modified construction as illustrated in Figures 4 and 5 the weft stops 56, 56' are designed to be movable so asto provide a gradual start up to unwinding the weftfrom the supply package. In other words, as seen in Figure 4, the weft stop is positioned furthertothe left as compared to Figures 1,2 and 3 so that the excess hair pin 54' of weft between the left-hand edge ofthe cloth, gripper 50' and the nose of inserter 4 when the gripper 50' releases the hair pin, is taken up slightly earlier but since the weft stop 56' then movestotherightitwill be providing someoftheweft required bythe inserter and the remainder will be drawn from the supply package thus avoiding any drastic pull upon the supply package.

The weft stop may be resiliently biased to the left or alternatively it can be mechanically moved to the right in timed sequence with the position ofthe inserter.

The stopper could, for example, be mounted eccentrically on a rotatable disc to rotate in a clockwise direction for the right-hand shed and anticlockwise for the left-hand shed. The speed of rotation will be calculated relative to the speed of the inserter to give the desired rate oftake-up of weft from the supply package when the inserter starts to draw yarn from it.

Itwill, of course, be appreciated that instead ofthe weft stop being designed to provide this function a separate simple compensator device would be implemented along the path ofthe weft between the guide member and the back eye ofthe inserter.

Atthe right-hand side of shed 12 and left-hand side of shed 10 a leno-mechanism may operate in conjunction with the selvedge hooks 46 and 22 respectively.

In the construction shown in Figures 1 to 5the inserter body is shorterthan the width of the shed and hence, as shown in Figure 1, the weft extends through part of the shed unsupported and unprotected. The inserter illustrated in Figures 11 and 12 in which the tubular body extends at 28 beyond the rear guide 38 to facilitate piecing-up by means of and airjet as illutstrated at 60 in dotted lines may be used, but the rear guide 38 will still pass into the shed.

In the construction illustrated in 15A and 1 SB, a high speed roller 62', driven thrnugh a power grip belt 64', is positioned between the guide member 20' and an additional guide 60' upstream ofthe guide member 20'. The roller rotates in the directon of draw off of the yarn from the supply 18' and is in slipping contact with the yarn which, because ofthe relative positions ofthe guide 60', roller62' and the guide member 20', contacts the surface ofthe roller over an arc. In practice it has been found that an arc in the region of 1 80' and a rollersurfacespeed of 10% to 30% above maximum yarn withdrawal speed by the inserterfrom the supply package, are ideal. When the tension on the yarn increases when the inserter is drawing yarn from package 18', the yarn pulls more tightly againstthe roller and hence is assisted by its forwarding action, thus significantly reducing thetension on the yarn.

As will be appreciated, the loom illustrated operates on the principle of double picks in each shed, i.e., two legs of weft in the form of a hair pin. A loom in accordance with the invention can operate either single or double picks.

Claims (20)

1. Ashuttleless loom ofthetype in which weftyarn from a supply source outsidethewarp shed, is inserted into the shed by means of a weft inserter which is reciprocated into and outfrom, the shed, wherein guide means are located in the weft yarn path between the weft supply source and the weft inserter, the relative position of the guide means and weft inserter path being such asto causetheweft inserter to withdraw and "excess" length of weft from the weft supply source during "reverse" movement of the inserterfrom the shed, a weft engaging member being provided to engage weft yarn extending from the front ofthe weft inserter when it is withdrawn from the shed so asto cause the said "excess" length of weft be held during thefirst part of the subsequentforward movement ofthe inserter into the shed, the weft engaging member being operableto disengage or releasetheweftduring a subsequent part of the forward movement ofthe inserter.

2. Ashuttleless loom as claimed in Claim 1, wherein the timing ofthe movement ofthe weft engaging member in conjunction with its position is such asto cause the inserterto commence pulling yarn from the supply package atan early stage of is forward strokewhilethe yflrn is still held bythe weft engaging member and the inserter is moving below its maximum velocity.

3. Ashuttleless loom as claimed in eitherClaim 1 or 2 in which a second weft engaging member is provided in a position such asto be engaged by a length of weft extending between the guide means and the inserterduringtheforward stroke ofthe inserter into the shed, the said second weft engaging member being arranged to move in the direction of movementofthe inserter so asto aid in supplying weft to the inserter during insertion.

4. Ashuttleless loom as claimed in any one of the preceding claims including a rotating member so positioned in the yarn path between the weft guide means and the inserter that weft yarn being withdrawn from the supply source during insertion engages the member.

5. Ashuttleless loom as claimed in any of the preceding claimswhereinweftyarnfrom a supply package is fed to the weft inserter at a point spaced rearwardlyfrom the head of the inserter.

6. Ashuttleless loom as claimed in Claim 5 in which weft from a supply package is arranged to pass through an eye atan angle to the longitudinal axis of the inserter and at the rearthereof, the weft then passing along thexbody oftheweft inserterto an outlet aperture attheforward end.

7. Ashuttleless loom as claimed in any one of the preceding claims wherein the weft inserter is mounted upon a perforated flexible tape which acts as a drive meansforthe inserter.

8. Ashuttleless loom as claimed in any one of the preceding claims having at leasttwo sheds, the inserters for each having a common drive mechanism acting to reciprocatetheweftinserters in the two sheds which are located at opposite sides of the drive means.

9. Weft inserter mechanism for a shuttleless loom ofthetype described comprising an elongated weft carrierwith means to cooperate with drive means which act to reciprocate the carrier into and out from a warp shed during use, front and rear weft guides being mounted on the carrier and spaced over a part of its length.

10. Weft inserter mechanism as claimed in Claim 9 in which the elongated carrier has teeth or spaces to mesh with the cooperating drive means.

11. Weft inserter mechanism as claimed in either Claim 9 or 10 wherein the elongated carrier is a flexible tape.

12. Weft inserter mechanism as claimed in any of Claims 9 toll wherein the front and rear weft guides are connected bya tubular member.

13. Weftinsertermechanism as claimed in Claim 1 2wherein the front and rearweft guides are holes integrally formed in the tubular member as a single unit, the tubular member being positioned above and substantially parallel with the carrier during use.

14. Weft inserter mechanism as claimed in any of Claims 9two 13 in which the rear guide is atan angleto the longitudinal axis ofthetubular member.

15. Weft inserter mechanism as claimed in any of Claims 9to 14 wherein the front of the inserter is formed as a nose providing a warp deflecting member.

16. Weft inserter mechanism as claimed in Claim 15 in which the front nose portion is displaced laterally from the carrier.

17. Weft inserter mechanism as claimed in any of Claims 9to 16 wherein the rear weftguide has an extension connected to the carrierto prevent weft looping underthe carrier.

18. Weft inserter mechanism as claimed in any of Claims9to 17 having at leasttwo elongated weft carriers, each carrier having oppositely disposed spaced pairs offront and rearweftguides.

19. A shuttleless loom substantially as hereinbe- fore described with reference to the accompanying drawings.

20. Aweft insertersubstantially as hereinbefore described with reference to Figures 6 to 14 of the accompanying drawings.