GB2074197A - Tension relievers - Google Patents

Abstract

A false twisting tension reliever is located between the delivery rollers and the yarn balloon of a ring spinner to produce a tension differential between the yarn forming the balloon, and the yarn travelling from the delivery rollers to the tension reliever. To facilitate piecing-up of the yarn after a breakage, the tension reliever has a drive wharf 82 and a capstan device 86 which includes a yarn engaging capstan element 102. The capstan device is slotted to permit threading in a radial direction, and having a snap-in connection with the wharf, so that the capstan device can be completely detached from the drive wharf for a piecing-up operation. <IMAGE>

Description

SPECIFICATION Improvements in or relating to textile spinning machines The present invention is concerned with spinning machines of the kind in which the yarn forms a balloon between the delivery position and the yarn package and the invention is particularly useful in a ring spinning machine. In an attempt to reduce the end-breakage rate in spinning machines of this kind, there have been various proposals to employ a false twist device located between the delivery position (usually the nip of a pair of drafting rollers) and the position at which the balloon effect begins (usually the guide eye).

Although the function of such a device has been regarded primarily as that of introducing twist into the yarn in the region where the yarn is weakest, that is to say where the yarn is leaving the delivery position, perhaps an even more important function is that of providing a tension differential in the yarn so that the tension in the yarn leaving the delivery device is lower than the tension in the yarn at the balloon. Admittedly, the guide eye itself must have some slight tension differential effect, but the introduction of a false twist device which actually nips the yarn has a more pronounced tension differential effect.For this reason, it is better to refer to the false twist device as a tension reliever -- and this expression will be used hereinafter-- but since the tension reliever has to rotate in sympathy with the balloon, to allow twist to be imparted to the yarn between the delivery position and the tension reliever, and since the twist is inhibited from travelling along the yarn by the guide eye, the tension reliever will incidentally create false twist in the yarn.

Now because the tension reliever has to grip the yarn in some way, it is necessary to thread the yarn through it each time there is a yarn breakage.

This threading operation can call for a certain dexterity, and is in any case somewhat tedious and therefore time consuming. It is the object of this invention to provide a tension reliever for a textile spinning machine, which can be easily and quickly threaded by the operative.

According to this invention a tension reliever for use in a textile spinning machine comprises a drive wharf adapted to be rotated about its own axis by a driving device in the machine, and a capstan device comprising a hollow body carrying a capstan element for the yarn, the capstan device having a releasable connection with the wharf, so that when engaged with the wharf it is adapted to be supported by and to rotate therewith (to rotate the capstan device) but so that it can be completely and easily removed from the wharf for the purpose of threading-up the yarn.

In the preferred construction, the hollow body has a snap-in connection with the wharf. It is further preferred that the capstan device is formed so that it permits yarn to be passed in a radial direction through its hollow body and engaged with the capstan element therein.

Preferably, one or both of the wharf and the hollow body is or are made of resilient material which permits the necessary distention and/or compression required during a snap-in fitting operation. It is further preferred, that the resilient wharf and/or hollow body does not form a complete annulus, so that it is-able to distend or contract as required during a snap-in fitting operation.

If the hollow body were in the form of a complete annulus, so that it formed an eye through which the thread had to be passed in an axial direction, and if in addition, the capstan device were permanently secured to the wharf, then threading up of the tension reliever after a yarn breakage, would be a delicate and tedious operation. It would be necessary to pass the yarn through the eye formed by the hollow body, and at the same time ensure that the yarn is engaged around the capstan element.In contradistinction to this, with the tension reliever in accordance with the invention, threading-up is a relatively simple operation, mainly because the capstan device is completely removed from the wharf, and therefore there is no accessibility problem, and partly because the yarn can be passed radially through the wall of the hollow body, without the necessity for threading it in an axial direction through the hollow body.

According to a preferred feature of the invention, the tension reliever also comprises a hollow axle and a journal bearing arranged between the hollow axle and the wharf. It is preferred that the capstan element extends axially from the hollow body into the hollow axle, when the hollow body is connected to the wharf. In the preferred construction, the hollow axle, wharf and hollow body are all substantially cylindrical members and the bore of the wharf is formed with an annular groove of rounded cross-section, the hollow body having an external rib of crosssection corresponding to the groove, the rib being a tight fit in the groove, to permit the snap-in interconnection between the wharf and the capstan device.

During a threading-up operation, it is of course necessary to pass the yarn axially through the bore of the hollow axle, but since the capstan device itself will have been removed from the wharf and the hollow axle at that time, this presents no problem, because the bore of the hollow axle can be relatively large, and relatively short in axial length.

The invention also includes a spinning machine fitted with a tension reliever in accordance with the invention located between a yarn delivery position and a yarn balloon position. In the preferred construction, the hollow axle of the tension reliever is carried by a plate movable between operative and inoperative positions, there being driving means on the machine engageable with the wharf when the plate is in the operative position and brake means on the machine engageable with the wharf when the plate is in the inoperative position.

It will be appreciated, that in practice, a tension reliever in accordance with the invention will be provided at each spindle position along the length of a spinning machine.

An arrangement on a ring spinning machine in accordance with the invention, will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a partly sectional and partly "exploded" view of a spinning machine, illustrating the location of a tension reliever in accordance with the invention, Figure 2 is a longitudinal section through a tension reliever, Figure 3 is a plan view of a capstan device for the tension reliever shown in Figure 2, Figure 4 is a perspective view of the capstan device shown in Figure 3, Figure 5 is an elevation of part of a mounting arrangement for a series of tension relievers, part of which is cut away, Figure 6 is an underneath view of the arrangement shown in Figure 5, Figure 7 is a section on the line VIl-VIl in Figure 5, and Figure 8 is a perspective view similar to Figure 4, but illustrating a capstan device with an alternative form of capstan element In Figure 1 there is illustrated part of a generally conventional ring spinning machine, which has been fitted with a tension relieving system in accordance with the invention. Two yarn spindles are shown at 10 and 12, and it will be appreciated, that the machine is equipped with a number of these spindles arranged in a row as is usual in this type of machine. Some distance above the spindles 10 and 12, there are corresponding drafting arrangements 20 and 22, and a third drafting arrangement 24 appertaining to an adjoining spindle (not shown) is also illustrated.A series of pigtail wire guide eyes 30, 32 and 34 each of which is associated with a corresponding spindle is also provided on the machine, the guide eyes being carried by brackets 36 extending from a fixed rail 38 which forms part of the machine structure.

In the ring spinning machine, a single sliver 50 from a supply package (not shown) is taken through the drafting device 22, and emerges from the nip of a pair of front rollers 40 and 42. The sliver 50 then passes in a substantially straight line to the corresponding guide eye 32, below which, it forms a spinning balloon indicated at 52, when the machine is in operation. This path of the sliver 50, which is being formed into a yarn by the spinning process, is repeated at each spindle position along the length of the machine, but as the arrangement is the same at each position, it is only necessary to describe what happens at a single position.

The spindle 10, 12, is rotated at high speed, and owing to the frictional retardation of the traveller (not shown) as it slides around the spinning ring, tension is induced in the yarn between the traveller and the nip of the front rollers 40 and 42. Twist is introduced into the yarn by the action of the ring traveller, and this twist runs back up the yarn from the guide eye 32, to the nip of the front rollers 40 and 42.However, close observation shows that as the substantially untwisted yarn emerges from the nip of the rollers 40 and 42, there is a very short V-shaped section of substantially untwisted yarn extending from the nip of the rollers, to a position where the twist begins to form in the yarn.It is this region which normally forms the weakest part of the yarn between the nip of the front rollers 40 and 42 and the traveller, and consequently most end breakages are likely to occur at this point. In fact, published information indicates, that the strength of the yarn in this very short V-shaped region is likely to be only about 40% strength of the twisted yarn where it is wound on to the package on the spindle.

With a view to minimising the number of end breakages, during a spinning operation, a yarn tension reliever indicated generally at 60 is provided on the machine, in association with each spindle position, and the yarn 50, is passed through the tension reliever 60. For this purpose of mounting the tension relievers 60 on the spinning machine, there is an inverted channel shaped rail 62 extending along the length of the machine, and rigidly secured to the machine framework. As illustrated in Figures 1, 5 and 6, the rail 62 provides a mounting for a series of driving rollers 64, there being one such driving roller 64 located between each adjacent pair of tension relievers 60.Each driving roller is free to rotate on a fixed axle 66 secured to the mounting rail 62 by a setscrew 68, and there is a driving belt 70 which extends along the length of the mounting rail 62 on the underside thereof (see especially Figure there being a driving mechanism (not shown) at one end of the machine for traversing the belt at relatively high speed. The belt 70 engages with a boss forming part of each driving roller 64, and there is an arrangement of jockey pulleys 72, which ensures that the belt 70 is pressed firmly against each of the driving rollers 64. Hence, during operation of the machine, the belt 70 causes each of the driving rollers 64 to be rotated about its own vertical axis.

Each tension reliever 60 is carried by a plate 74 mounted inside the channel-shaped mounting rail 62, and pivoted on a pin 76 (see Figure 7).

The tension reliever 60 essentially comprises a hollow axle 80, secured to the pivoted plate 74, a drive wharf 82 rotatably mounted on the axle 80 by means of a ball-bearing 84, and a capstan device 86 detachably connected to the drive wharf 82 as will be hereinafter described. The axle 80 may be made as a diecasting, or moulded in plastics material, and its function is simply that of providing a location for the inner race of the ballbearing 84, the drive wharf 82 being a press-fit on the outer race of the ball-bearing.

Now the pivoted plate 74 is ioaded by a spring 88, one end of which is secured to a setscrew 90 fastened into the mounting rail 62, the other end being hooked into a notch 92 formed in the pivoted plate 74. The arrangement of the spring 88, is such that it provides an "over centre" arrangement for the plate 74, whereby the latter is spring loaded into either of two positions. One of these, the operative position is illustrated in Figure 6, wherein the drive wharf 82 is pressed into engagement with a periphery 94 of the driving roller 64, whereby when the driving roller is rotated, this produces rotation of the driving wharf 82, as permitted by its journal mounting on the hollow axle 80.Also, since the capstan device 86 is secured to the drive wharf 82, the capstan device will also rotate about the longitudinal axis formed by the bearing 84, and passing through the centre of the hollow axle 80. On the other hand, when the pivoted plate 74 is moved into its inoperative position, the drive wharf 82 is engaged with a brake pad (not shown) attached to the inside of the mounting rail 62, whereby rotation of the drive wharf 82 and the capstan device 86 can be very rapidly arrested. Hence, so long as the pivoted plate 74 is in the operative position, the capstan device 86 is rotated at a high speed, but as soon as the plate 74 is moved through an angle sufficient to pass over centre, the spring loading provided by the spring 88, forces the tension reliever into the inoperative position, where rotation of the capstan device ceases almost immediately.For the purpose of moving the tension reliever between its operative and inoperative positions, there is a finger 96 projecting downwardly from the plate 74, to a position, where it is accessible beneath the mounting rail 62. In fact, as illustrated in Figure 5, the finger 96 projects below the mounting rail 62.

A hole 98 is formed in the mounting rail 62 at each position corresponding to the operative position of one of the tension relievers, so that the axis of each tension reliever, is coaxial with the corresponding hole 98 in the mounting plate 62, whenever the tension reliever is in the operative position.

Turning now to Figures 2, 3 and 4, the capstan unit 86 essentially consists of a generally annular hollow body 100, and a capstan element 102. The hollow body 100 is moulded in plastics material, which has adequate strength, but which also possesses a degree of resilience. As is clear from Figures 3 and 4, the hollow body 100 does not subtend a full 1 800 about the vertical axis, but has a radial gap 104 formed through its wall, this gap extending throughout the axial length of the body 100.The lower portion of the body 100 is of the same external diameter as the drive wharf 82, and is formed with external grooves 106 which facilitate the gripping of the body 1 00 by the hand of an operative, and the upper portion of the body 100 is of somewhat reduced outside diameter and is formed with a rib 108 of substantially semicylindrical cross-section (see Figure 2) at its top end. Internally, the body 100 has a relatively small bore 110 at its upper end and a frusto-conical bore 112 in its lower portion.

The capstan element 102 takes the form of a rod-like member made in metal, a root portion 114 thereof being embedded in the hollow body 100, during the moulding of that body. As clearly shown in the drawings, the upper portion of the capstan element 102 includes a vertical section 11 6 and an axial line on the periphery of this vertical section 11 6 always lieson the vertical axis of rotation of the capstan device 86.

Consequently, when the capstan device 86 is rotated, the vertical section 11 6 gyrates about the axis of rotation, but the vertical section always lies very close to the axis of rotation. Above the vertical section 116, there is an out-turned radial portion 11 8 which passes through the axis of rotation.

The bore of the lower portion of the drive wharf 82 is formed with a frusto-conical portion 120 and with a groove 122, which has substantially the same cross-sectional shape as that of the rib 108 formed on the body 100 of the capstan device 86.

Thus, it is possible to introduce the upper part of the body member 100 into the frusto-conical portion 120 of the bore of the drive wharf 82, and when the rib 108 engages with the smaller diameter upper end of the frusto-conical portion 120, then by exerting upward pressure on the body 100, it is possible to cause that body to contract slightly in diameter, as permitted by its resilience and by the gap 104, until the rib 108 has passed over the obstruction provided by the narrow bore end of the frusto-conical portion 120 and engaged in the groove 122. In other words, the hollow body 100, is a snap-fit in the drive wharf 82. In order to assist in the snap-in fitting, it may be desirable for the operative to squeeze the hollow body 100 in the hand, in order to slightly close up the gap 104.When it is required to detach the capstan device 86 from the drive wharf 82, the body 100 is gripped by the operative, and simply pulled vertically downwards, whereupon, the body 100 contracts again slightly, to allow the rib 108 to pass over the obstruction provided by the small diameter end of the frusto-conical portion 1 20. The snap-in fitting of the capstan device 86 into the drive wharf 82 provides a significant advantage in the piecing-up operation, as will appear hereinafter. When the capstan device 86 is fitted to the drive wharf 82, as illustrated in Figure 2, the vertical section 11 6 of the capstan device 102 lies within the bore of the hollow axle 80, and the hook portion 11 8 of the element 102 lies within an enlarged bore of the hollow axle 80. However, the capstan element 102 is in a relatively inaccessible position on the machine, as is clear from Figure 1, because in addition to being within the hollow axle 80, it is also beneath the web of the mounting rail 62, and access to it has to be gained through the hole 98 in the rail 62. Furthermore, when the tension reliever is in the operative position aligned with the hole 98, it will generally be rotating, because it is then in the operative position. When the tension reliever is stationary, it will generally be in the inoperative position, wherein the capstan element 102 is even more inaccessible.

The yarn 50 is wrapped around the vertical section 1 6 of the capstan element 102 as shown in Figure 1, in order to provide the tension relieving effect. Because of the capstan effect produced by the wrapping of the yarn 50 around the capstan element 102, the tension in the section of the yarn between the tension reliever 60 and the nip of the front rollers 40 and 42 is only a small fraction of the tension in the yarn below the tension reliever 60. Hence, whilst it is possible to operate the spinning machine to produce the desired tension in the spinning balloon 52, that tension is not transmitted back to the weak region of the yarn where it emerges from the nip of the front rollers 40 and 42.

Consequently, the incidence of yarn breakage at this weak position is very much reduced, and practical trials have confirmed this.

Clearly, it is essential to ensure that at least some twist is introduced into the yarn between the nip of the front rollers 40 and 42 and the tension reliever 60, since otherwise the provision of the tension reliever 60 would simply have shortened the length of yarn in which twist is being inserted. Because the capstan element 102 rotates about the longitudinal axis which is coincident with the general direction of the yarn path, twist is in fact introduced into the upper section of the yarn between the delivery rollers and the tension reliever and the driving arrangement comprising the belt 70, the driving roller 64 and the drive wharf 82, is so arranged, that this twist is inserted at virtually the same rate as in the section below the tension reliever.In practice, it is not essential to rotate the tension reliever at precisely the same angular velocity as the spinning balloon, since so long as a substantial amount of twisting takes place as the yarn is travelling from the front rollers 40 and 42 to the tension reliever 64, that suffices. In other words there could be a small difference between the amount of twist inserted above and below the tension reliever, without materially affecting the overall performance of the spinning operation.

In a practical test a single spindle station on a ring spinning machine was modified in accordance with the apparatus described above, and then identical yarns were spun at this station and on other conventional spinning stations not equipped with the tension reliever device on the machine.

Once spinning was in progress, the yarn being produced was gradually weakened by reducing the twist. One by one, the yarn ends broke at the conventional spindles, whilst at the modified spindle position, spinning continued. This process has been repeated several times, and provides the effectiveness of the tension reliever in reducing end breakage rate in a ring spinning apparatus.

However, the undoubted operational advantage of the tension reliever could be offset, if there were practical difficulties in piecing-up broken yarns at a spindle station equipped with a tension reliever, since inevitably piecing-up operations will be required even when tension relievers are fitted.

Now it will be obvious, by reference to Figure 1, that if the operative had to attempt to thread the yarn through the tension reliever, passing it through the hollow axle 80 and through the hollow body 100, in an axial direction, and at the same time, wrapping the yarn around the capstan element 102, that operation would require considerable dexterity, and would probably delay a piecing-up operation. With the arrangement which has been described however, piecing-up can be carried out rapidly and effectively as follows:- On finding a broken yarn, the operative pushes the finger 96, to move the tension reliever 64 appertaining to the broken yarn from the operative to the inoperative position. This has the effect of arresting rotation of the capstan device 86.The operative then grips the projecting lower end of the body member 100 and pulls it downwardly, detaching it from the drive wharf 80. Preferably, the capstan unit 86 which is then completely free is cleaned, and the operative places it in a pocket.

Next, the operative stops the spindle appertaining to the broken yarn by use of the conventional spindle brake. Then yarn is pulled back off the package on the spindle, threaded through the traveller and through the guide eye 32 or 34 in the usual way, through the hollow axle 80 (this presents no problem, because of the relatively large bore and relatively short axial length of the hollow axle) and the end of the yarn thus drawn back and threaded through the hollow axle is held by the operative above the mounting plate 62.

Next, the operative takes the capstan device 86, passes the length of yarn extending from the guide eye to the hollow axle 80 through the radial gap 104 and then engages the capstan device 86 in the drive wharf 82 by upwardly applied pressure as previously described. At this stage, it is possible to wind the yarn around the capstan element 102 simply by engaging it over the hook portion 118.

In fact, the capstan device 86 can be manipulated during the fitting operation, so that the capstan element 102 "winds itself" on to the yarn.

At that stage, the finger 96 is used to return the tension reliever to the operative position, so that the capstan device 86 begins to rotate and at the same time, the operative releases the spindle brake and once a slight tension is felt in the end of the yarn gripped by the operative, above the rail 62, that end of yarn is spliced to the sliver emerging from those rollers, in the conventional manner. Now it will be appreciated, that throughout the piecing-up operation, there is no awkward threading of the yarn through a relatively small eye, this being due to the fact that the capstan device 86 is completely detachable from the drive wharf, and due also to the gap 104 in the body member 100. Thus, the gap 104 performs two functions, in that it assists in the threading of the yarn through the capstan device, and it also facilitates compression of the body member 100, for the purpose of the snap-in fitting.

Figure 8 illustrates an alternative form of capstan device 186, having a body member 200 identical with the body member 1 00. In this construction however, there is a capstan element 202 which is generally of Z-shape. The lower end of the capstan element 202 is embedded in the body 200, the upper end 218 forms a hook portion, and the intermediate portion 21 6 lies close to the vertical axis about which the device 1 86 is rotated. In fact, with this construction, the section 21 6 of the element 202 may be inclined to the vertical, and pass through the axis of rotation from one side to the other. Apart from the difference in the shape of the capstan element itself, the device illustrated in Figure 8 is the same as that illustrated in Figure 4, and it is operated in the same manner.

A tension reliever as described above, also forms the subject-matter of Patent Application No: CASE B.

Whilst in the above described examples, the hollow body 100 or 200 is made in a resilient material, it will be appreciated that as an alternative, the drive wharf could be made in resilient material to permit the snap-in fitting.

Indeed, the drive wharf itself could be discontinuous in a circumferential direction, so that it has some facility for distention, during the snap-in fitting operation. Alternatively of course, both drive wharf and hollow body could be made resilient.

An advantage of the construction described above is that it is possible to change the capstan device 86 quite readily. This may be done to provide a different type of capstan, for example a device such as that shown in Figure 8 could be substituted for that shown in Figure 4. If the tension relieving effect is not required for a particular spinning operation, then it is only necessary to remove the capstan devices, the yarns then passing unimpeded through their respective hollow axles.

Instead of the hollow body 1 00 being a snap-in fitting in the wharf 82, it may be screwed into it, preferably with a coarse thread to provide for rapid connection and release, or a bayonet-and-socket connection may be employed.

Claims (13)

1. A tension reliever for use in a textile spinning machine comprising a drive wharf adapted to be rotated about its own axis by a driving device in the machine, and a capstan device comprising a hollow body carrying a capstan element for the yarn, the capstan device having a releasable connection with the wharf, so that when engaged with the wharf it is adapted to be supported by and to rotate therewith (to rotate the capstan device) but so that it can be completely and easily removed from the wharf for the purpose of threading up the yarn.

2. A tension reliever as claimed in Claim 1, in which the hollow body has a snap-in connection with the wharf.

3. A tension reliever as claimed in Claim 1 or Claim 2, in which the capstan device is formed so that it permits yarn to be passed in a radial direction through its hollow body and engaged with the capstan element therein.

4. A tension reliever as claimed in Claim 2 or Claim 3, as dependent from Claim 2, in which one or both of the wharf and the hollow body is or are made of resilient material to permit the necessary distention and/or compression required during a snap-in fitting operation.

5. A tension reliever as claimed in Claim 4, in which the resilient wharf and/or hollow body does not form a complete annulus, so that it is able to distend or contract as required during a snap-in fitting operation.

6. A tension reliever as claimed in Claim 3, or in either of Claims 4 and 5 as dependent from Claim 3, in which the hollow body is formed with an axially extending slot from end-to-end thereof, so that a thread can enter the hollow body through the slot.

7. A tension reliever as claimed in any one of Claims 1 to 6, which further comprises a hollow axle and a journal bearing arranged between the hollow axle and the wharf.

8. A tension reliever as claimed in Claim 7, in which the capstan element extends axially from the hollow body into the hollow axle when the hollow body is connected to the wharf.

9. A tension reliever as claimed in Claim 8, wherein the hollow axle, wharf and hollow body are all substantially cylindrical members and the bore of the wharf is formed with an annular groove of rounded cross-section, the hollow body having an external rib of cross-section corresponding to the groove, the rib being a tight fit in the groove, to provide the snap-in interconnection between the wharf and the capstan device.

10. A tension reliever constructed and arranged substantially as herein described with reference to Figures 1 to 7 or Figures 1 to 7 as modified by Figure 8 of the accompanying drawings.

11. A spinning machine having a tension reliever as claimed in any one of Claims 1 to 10, located between a yarn delivery position and a yarn balloon position.

12. A spinning machine as claimed in Claim 11, but in which the tension reliever is in accordance with Claim 7, in which the hollow axle of the tension reliever is carried by a plate movable between operative and inoperative positions, there being driving means on the machine engageable with the wharf when the plate is in the operative position and brake means on the machine engageable with the wharf when the plate is in the inoperative position.

13. A spinning machine constructed and arranged substantially as herein described with reference to Figures 1 to 7 or Figures 1 to 7 as modified by Figure 8 of the accompanying drawings.