WO1981002591A1

WO1981002591A1 - Weft projection means

Info

Publication number: WO1981002591A1
Application number: PCT/GB1981/000032
Authority: WO
Inventors: J Griffith
Original assignee: Bonas Machine Co; J Griffith
Priority date: 1980-03-05
Filing date: 1981-03-03
Publication date: 1981-09-17
Also published as: JPS57500250A; EP0047260A1

Abstract

Weft yam inserting means for a fluid loom, the inserting means including a fluid jet nozzle through which the yarn to be inserted is passed, positive feed means for positively feeding the weft yarn to the nozzle, the direction of feed from the positive feed means being substantially in line with the direction of weft insertion so that the positive feed means and jet nozzle together propell the weft yam across the warp shed, the jet nozzle and positive feed means being arranged for each weft insertion cycle to smoothly accelerate the weft yam to a maximum speed of insertion and then smoothly decelerate the weft yarn to a stanstill at termination of the weft insertion cycle.

Description

WEFT PROJECTION MEANS

The present invention relates to a weft projection means, in particular a weft projection means for use in a fluid jet loom.

In a fluid jet loom having a guide channel for guiding yarn across a warp sheet it. is necessary to project weft yarn into and along the guide channel in a controlled manner so that there is minimal risk of the weft yarn jumping out of the channel. The speed of insertion of the weft yarn across the warp shed is a limiting factor in the speed of operation of the loom. Accordingly it is desirable to achieve weft insertion as quickly as possible whilst maintaining a desired degree of control on> the yarn.

According to the present invention there is provided a weft yarn inserting means for a fluid loom, the inserting means including a fluid jet nozzle through which the yarn to be inserted is passed, positive feed means for positively feeding the weft yarn to the nozzle, the direction of feed from the positive feed means being substantially in line with the direction of weft insertion so that the positive feed means and jet no2zle together propell the weft yarn across the warp shed, jet nozzle and positive feed means being arranged for each weft insertion cycle to smoothly accelerate the weft yarn to a maximum speed of insertion and then smoothly decelerate the weft yarn to a standstill at termination of the weft insertion cycle.

Reference is now made to the accompanying drawings, in which:-

Figure 1 is a perspective view of a weft inserting means according to the present invention; Figure 2 is an end view of the feed rollers shown in Figure 1; Figure 3 is a partial plan view of the weft inserting means shown in Figure 1;

Figure 4 is a graphic representation of the speed of insertion of weft yarn during insertion across the warp shed;

Figure 5 is a schematic end view of one form of weft selection means; and

Figure 6 is a schematic end view of an alternative weft selection means. Referring initially to Figure 1 there is partially shown an air jet weaving loom 10 which includes a beat up bar 11 on which a row of beat up reeds 12 are mounted. In front of the reeds 12 is a row of channel shaped teeth 14 which collectively define a channel along which the weft yarn is to be guided during the weft insertion cycle. For the sake of simplicity the remaining conventional components of the loom have been omitted.

The weft yarn insertion means according to the present invention is generally shown at 20 and includes an air jet nozzle 21, and a positive feed means in the form of a pair of nip feed rollers 22 and a movable yarn guide 23.

The air jet nozzle 21 includes an air chamber 24 which has an inlet 25 for pressurised air, a yarn inlet 26 and an outlet conduit 28 from which pressurised air and weft yarn 30 are expelled. The conduit 28 is mounted in a bearing 33 which in turn is mounted on a bracket 34 fixedly mounted on the beat up bar 11. The exit mouth 28a of conduit 28 is closely spaced from the first channel shaped teeth 14 to enable reliable entry of air and weft yarn into the channel defined by teeth 14. The chamber 24 is pivotally mounted on a base plate 40 of the loom by means a metallic ribbon 41 so that on rotation movement of the beat up bar 11 the nozzle 21 pivots with the bar 11. The length of conduit 28 and positioning of bearing 33 are such that the exit mouth of conduit 28 is always directed into the channel defined by teeth 14 during weft insertion despite rotational movement of bar 11. Spaced upstream and substantially in alignment with the direction of weft insertion, from the air jet nozzle 21 are the nip feed rollers 22. As seen in Figures 1 and 2 the nip feed rollers 22 are of.frusto conical shape and they are arranged one above the other so that the line of contact, between them is substantially parallel to the surface of base plate 40.

The lower feed roller.22a has a fixed axis of rotation and is continuously driven at a constant speed from a drive shaft 45. The upper feed roller 22b is movably mounted with respect to the lower roller so that its axis of rotation may be deflected. This is achieved by pivotally connecting the shaft 50 on which roller 22b is rotatably mounted to a link member 51 which in turn is pivotally mounted on a support 52 projecting above base plate 40. A resilient spring 60 extends between the link member 51 and support 52 and serves to resiliently urge upper roller 22b into contact with the lower roller 22a. Due to the peripheral contact between rollers 22a and 22b roller 22b is driven by roller 22a. The surface of each roller 22a, 22b is preferably of a resilient material such as a polyurethane, so that the surface of the rollers indent slightly when yarn is trapped therebetween. Additionally, when yarn passes between the rollers, upper roller 22b will tilt relative to the lower roller 22a. to accommodate the yarn and will maintain surface contact between the upper and lower rollers so that driving contact is maintained therebetween.

Weft yarn 30 is fed inbetween rollers 22a, 22b by means of the yarn guide 23. The yarn guide 23 includes a guide arm 70 which at its terminal end has a hook 71 for engaging yarn 30. The arm 70 forms part of a parallel linkage 73 which is acted upon by a reciprocal push rod 74. On reciprocation of push rod 74 the hook 71 is caused to move in a substantially linear path just behind the nip region of the rollers 22 as seen in Figure 3. For the sake of simplicity the upper roller 22b has been omitted from Figure 3. Movement of push rod 74 is achieved via a cam 76 on a continuously rotating shaft 77 which actuates a cam follower 78 on a pivoted lever 79; the lever 79 being pivotally attached to the push rod 74.

In use, at the beginning of the weaving cycle weft yarn 30 extends between the jet nozzle 21 and a stationery guide eye 32 on the base plate and the hook 71 is located on the side of yarn 30 opposite to the feed rollers 22. Initially hook 71 is moved toward yarn 30 to pick up the yarn and move it toward the nip between rollers .22. Just before entry of the yarn 30 into the nip between rollers 22 a switch (not shown) is actuated to switch on pressurise air supply to the nozzle 21. The effect of this is to cause the yarn to begin to accelerate through-the-nozzle-21. As soon as the yarn enters the nip between rollers 22 it is positively driven thereby and so is positively fed into nozzle 21. The rate at which the yarn 30 is fed to nozzle 21 is progressively increased as the hook 71 progressively moves towards the larger diameter ends of rollers 22. When hook 71 reaches this position it dwells there for a predetermined period of time, for which period of time the yarn is fed at a constant rate to nozzle 21. After this predetermined period of time the hook 71 begins to move back to its initial position. Accordingly as it moves toward the smaller diameter ends of the rollers the yarn feed rate decreases causing a controlled deceleration of the yarn. Just after the yarn being moved from the nip of the rollers the switch controlling air supply to the nozzle 21 is switched off so that yarn feed is completely stopped. The above weft inserting means enables the weft yarn to be smoothly yet rapidly accelerated into the channel defined by teeth 14 and then after being fed at its maximum rate of feed decelerated in a smooth manner to stop by which time the leading end of the weft yarn would have reached a desired position .across the warp sheet. The rate of feed across the warp sheet is illustrated graphically in Figure 4. In Figure 4 region A is the initial acceleration due to the air jet nozzle 21 alone; region B is the acceleration due to the yarn being moved from the smaller to the larger diameter ends of the rollers 22; region C is the constant feed rate whilst the yarn 30 is held at the larger diameter ends of the rollers 22; region D is the deceleration caused by the yarn 30 being moved from the larger to the smaller diameter ends of rollers 22; and region E is the deceleration due to switching off the air jet nozzle 21. It will be appreciated from Figure 4 that the acceleration/deceleration curve for the yarn is smooth which is important in controlling movement of the yarn across the warp shed since it substantially eliminates whip lash of the yarn which in turn reduces the likelihood of the yarn jumping out of the channel defined by teeth 14. The rate of acceleration and deceleration is controlled by moving the yarn guide hook 71 at a desired speed across the rollers (determined by the shape of cam 76), by the included angle of each of the conical rollers 22a, 22b and by their speed of rotation.

The weft inserting means as referred to above is constructed in a manner such that a single weft yarn 30 can be delivered to a fluid jet nozzle means 21. However, the invention is not restricted to such means and the invention includes weft inserting means which can be used to supply selectively one of a plurality of weft yarns as can be seen from the modifications illustrated in Figures 5 and 6. Referring first to Figure 5 there is schematically shown a weft inserting means similar to that of Figures 1 to 3. To supply one of a plurality of different weft yarns the weft inserting means .of Figures 1 to 3 is modified by providing a weft selection means in the form of a reciprocable lever 124 in which there is a plurality of weft yarn guide eyes 125 arranged at spaced intervals along the lever. This lever 124 can be moved to align a selected guide eye 125 and thus a particular weft yarn with the nip between the feed rollers 22. Thus when hook 71 is advanced it will pick up the yarn in the selected guide eye and feed it between the rollers 22.

Alternatively as shown in Figure 6 the weft selection means can be in the form of a weft yarn deflector lever 128 for each of a plurality of weft yarns 129, each such lever 128 is notched, as at 130, at its free end and is reciprocable to align its weft yarn 129 with the nip of the feed rollers 22 in order that the reciprocable hook 71 can move the so aligned weft yarn 129 into the nip of the feed rollers 22. While we have illustrated weft selector means which will enable any one of four different weft yarns to be fed to the fluid jet nozzle 21 it will be appreciated that in either of the arrangements of Figures 5 and 6 more or less than four such weft yarns can be selectively fed either by providing more or less than four guide eyes 125 in the arrangement of Figure 5 or more or less than four deflector levers 128 in the arrangement of Figure 6.

It will be appreciated that the levers 128 of Figure 6 may be located below the weft yarns 30 if desired. An advantage of the invention disclosed above lies in the fact that, during the major portion of insertion of a weft yarn the fluid jet nozzle 21 only has to accelerate that portion of weft 11 lying in front of the rollers and to keep the yarn 11 moving. This means firstly that faster insertion speeds can be attained, and secondly that a greater range of types of yarns can be inserted than either the fluid jet nozzle 21.on its own, which could not accelerate yarns with a relatively low air resistance, or rollers 22 on their own, which could project yarns of a high air resistance but could not keep them going for any distance in the shed.

A further advantage of the invention is that the rollers 22 may be used to measure the correct length of yarn being inserted, this being especially useful when the invention is used in conjunction with weft selection means as shown in Figures 5 and 6.

Claims

1. Weft yarn inserting means for a fluid loom, the inserting means including a fluid jet nozzle through which the yarn to be inserted is passed, positive feed means for positively feeding the weft yarn to the nozzle, the direction of feed from the positive feed means being substantially in line with the direction of weft insertion so that the. positive feed means and- jet nozzle together propell the weft yarn across the warp shed, the jet nozzle and positive feed means being arranged for each weft insertion cycle to smoothly accelerate the weft yarn to a maximum speed of insertion and then smoothly decelerate the weft yarn to a standstill at termination of the weft yarn insertion cycle.

2. Weft inserting means according to Claim 1, wherein the positive feed means includes a pair of nip rollers of conical shape having their smaller ends side by side, and a yarn guide means for moving the weft yarn to be inserted into the nip region between the rollers at their smaller ends and toward their larger ends and then subsequently moving the weft yarn to its initial position during each weft insertion cycle.

3. Weft insertion means according to Claim 2 , wherein the nip rollers are continuously rotating at a constant speed and that the rate of acceleration and deceleration of the weft yarn caused by the nip rollers is controlled by the included angle of the concial rollers and the rate of insertion and retraction of the weft yarn by the yarn guide means.

4. Weft insertion means according to Claim 2 or 3, wherein a first of the nip rollers is driven and has a fixed axis of rotation, and the second roller is arranged to be driven by the first roller by surface contact there with, the second roller having an axis of rotation which can tilt relative to the first roller so as to ensure peripheral contact between the rollers when the weft yarn is received therebetween.

5. Weft insertion means according to any preceding claim, wherein weft selection means are provided for selectively feeding a desired weft yarn to the positive feed means.

6. Weft insertion means according to any of Claims 2 to 4, wherein the weft selection means are provided between the nip rollers and the yarn guide means, the selection means being operable to present a desired weft yarn into the path of movement of the guide means so that the guide means moves the desired weft yarn into the nip between the rollers.