GB2231590A - Yarn selection in axminster carpet looms - Google Patents

Abstract

A respective elongate yarn carrier (14), having means (16) for locating a plurality of yarns (12) at intervals along its length is associated with each gripper (10) of the loom and is axially displaceable to present a chosen yarn to its gripper so as to form a pattern in the carpet being produced. For selective axial displacement of the yarn carrier (14), a displaceable engagement device, such as toothed shoe (38), engages an elongate entrainment device (28) by intermeshing of their respective teeth (40, 36). In this respect, the entrainment device (28) is attached to the carrier bar (20) by a resilient spring- loaded connection (29) and is deflectable, contrary to spring bias, by means of a solenoid actuated plunger (34) to engage (or disengage) the device (38) at a selected position during its displacement. <IMAGE>

Description

YARN SELECTION IN AXMINSTER CARPET LOOMS This invention concerns yarn selection in gripper Axminster carpet looms.

Typically, in such looms each gripper has associated therewith a respective elongate bar-like yarn carrier having a plurality of apertures through each of which extends a respective yarn from a supply, these yarns being, for instance, of different colours so that longitudinal displacement of the carrier enables the yarns selectively to be offered to the gripper for a length to be drawn off, severed from the supply, and brought into position to be incorporated into the carpet being woven to produce a desired pattern therein.

In our earlier U.K. patent application serial No.

2189515 we disclosed a loom of this type, which avoids use of a Jacquard control mechanism and is thus less complex, less expensive, and easier to maintain than earlier Jacquard controlled looms and is also economically viable for short runs of a particular pattern. In the loom disclosed in the aforesaid application each gripper has associated therewith a respective elongate yarn carrier having means for locating a plurality of yarns at intervals along its length, each carrier being axially displaceable to present a chosen yarn to an associated gripper according to the longitudinal position of the carrier, means for the axial movement of the carrier comprising an engagement device displaceable in sequence with the gripper and an associated entrainment device comprising an elongate member extending generally in the axial direction of its carrier and pivoted end to end therewith, one of said engagement and entrainment devices comprising a plurality of teeth and the other of said devices having at least one co-acting tooth wherewith said engagement and entrainment devices are releasably engageable with one another, and control means serving, during displacement of the engagement device, to effect engagement of said devices by pivoting said elongate member so as to obtain selective longitudinal movement of the carrier to present a corresponding selected yarn to the respective gripper.

Connection of the entrainment device to the engagement device is achieved by means of a respective solenoid or pneumatic ram which serves to pivot the entrainment device towards the engagement device to bring their teeth into mesh.

The pivotal connection between each elongate, tooth-bearing entrainment device and its respective yarn carrier was, accordingly, an essential feature of our previous proposal. As the yarn carriers and their entrainment devices are closely packed, side by side, with only a small clearance therebetween it is important that they should be accurately aligned otherwise errors in the yarn selection mechanism will occur. It is also important that axial thrust be effectively transmitted between the carriers and their respective entrainment devices.For these reasons it was proposed that the carriers and the respective entrainment devices pivoted thereto should be substantially coplanar and the preferred pivotal connection was disclosed as a hinge joint formed between an arcuate male bearing and a matching arcuate female recess in the adjoining ends of each carrier and its entrainment device, the alignment being maintained by washers bearing against the side faces of the joint, and secured by a rivet through the male bearing.

It is an object of the present invention to provide a comparable loom mechanism with an alternative form of connection between the yarn carriers and their entrainment devices, which connection is even more reliable, less prone to wear, misalignment or other faults than the aforesaid pivotal connection, and which has other constructional and operational advantages, as will emerge hereinafter.

According to the invention, there is provided a gripper Axminster carpet loom in which each gripper has associated therewith a respective elongate yarn carrier having means for locating a plurality of yarns at intervals along its length, each carrier being axially displaceable to present a chosen yarn to an associated gripper according to the longitudinal position of the carrier, means for the axial movement of the carrier comprising an engagement device displaceable in sequence with the gripper and an associated entrainment device comprising an elongate member extending generally in the axial direction of its carrier and attached thereto by a resilient spring-loaded connection, one of said engagement and entrainment devices comprising a plurality of teeth and the other of said devices having at least one co-acting tooth wherewith said engagement and entrainment devices are releasably engageable with one another, and control means serving, during displacement of the engagement device, to effect engagement or disengagement of said devices by deflecting the elongate member against the spring bias of the connection so as to obtain selective longitudinal movement of the carrier to present a corresponding selected yarn to the respective gripper.

The yarn carrier and the entrainment device are preferably connected end to end to minimise the lateral extent of the mechanism, enable close spacing of the yarn carriers, and ensure effective transmission of force therebetween in the axial direction of the carriers.

Each entrainment device may be connected to its carrier by a respective connection element in the form of leaf spring. Alternatively, the entrainment devices may effectively comprise elongate leaf springs and make the connection direct. In this case the entrainment devices may consist of wires, or narrow strips of metal, and the teeth for engagement with the engagement devices may be formed integrally as kinks or bent portions of these wires or strips.

In preferred embodiments of the invention each entrainment device effectively comprises a rack connected to the yarn carrier and deflectable laterally to engage with and disengage from the engagement device.

In this respect, the entrainment device and its carrier are preferably arranged at an inclined angle, or else substantially horizontally, such that the entrainment device is spring biased to a lower position and is deflectable upwardly to engage with the engagement device by intermeshing of the respective teeth of the devices. The arrangement could, however, be such that the entrainment device is spring biased to a 'normal' or 'rest' position in engagement with the displaceable engagement device and is deflectable out of engagement only when the selected carrier position is attained.

An advantage of the presently proposed deflectable form of connection between entrainment device and carrier over the previous pivoted connection is that it is me~hanically simpler to accomplish in a manner which maintains alignment of the carriers and their respective entrainment devices. Also it is less liable to wear or fault, which could give rise to incorrect carrier displacement and errors in yarn selection.Furthermore, the spring bias applied to the connection ensures, in the preferred arrangement, positive disengagement of the entrainment device from the engagement device whenever the former is no longer supported in a deflected position (or, in the alternative arrangement, positive engagement of the devices) and this further mitigates any possibility of sticking either of the engaged devices or of adjacent entrainment members which might lead to faulty yarn selection.

The engagement device may take the form of a toothed sector or gear wheel which is rotated back and forth in synchronism with the operation of the gripper.

Alternatively it may comprise a toothed element or rack which effects linear movement in synchronism with operation of the gripper. In this latter case the engagement device may comprise a reciprocable shoe with rack teeth or a single tooth that extends laterally across a series of entrainment devices, and each entrainment device may then comprise, in the former case a single tooth or, in the latter case, a toothed rack.

The arrangement is preferably such that connection of the entrainment device with the engagement device occurs during forward movement of the engagement device so that the carrier is entrained by the engagement device as the latter moves to an end position, from which it then returns to a starting or rest position.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which:- Fig. 1 is a diagrammatic elevation illustrating, from a first embodiment of gripper Axminster loom according to the invention, those parts necessary for understanding the invention; Fig. 2 is an enlarged fragmentary side elevation of a yarn carrier connected to its entrainment device in the loom embodiment of Fig. 1; Fig. 3 is a further enlarged, exploded perspective detail showing how a connection spring is fitted to the yarn carrier; Fig. 4 is a view similar to Fig. 2 showing an alternative form of entrainment device connected to the yarn carrier; Fig. 5 is a view similar to Fig. 1 of a second embodiment of the loom of the invention.

Fig. 1 illustrates a part of a gripper Axminster loom comprising a series of grippers 10, only one of which is illustrated, mounted on a common support (not shown). In known manner, during each cycle of operation of the loom, the grippers 10 swing on their support between a yarn-take-up position, in which the illustrated gripper (10 appears in Fig. 1, to a yarninserting position (not shown). Respective yarn carriers 14 are associated with the individual grippers 10. The yarn carriers for the respective grippers are arranged in banks, side-by-side, on a common support so that only one carrier and its gripper can be seen in the plane of Fig. 1.

rs the take-up position, each gripper grips a selected one of a plurality of tufting yarns 12 presented from a supply (not shown) by its yarn carrier, and draws off a short length of the yarn which is then cut off by means (not shown) which may be of conventional form. In the inserting position, the gripper inserts the cut-off yarn length into the shed (not shown) to be incorporated into the fabric being woven. As will be seen, the yarns 12 extend through respective openings 16 forming guides through each yarn carrier 14 at intervals therealong, and the selected yarn 12 is presented to the gripper 10 by controlled longitxdinal displacement of the carrier 14.For ease of illustration, the openings 16 are shown as being relattvely closely spaced in the carrier, but in practice they hold the yarns 12 somewhat more widely spaces The longitudinal axes of the carriers are preferably inclined to the horizontal, with the grippers at the lower ends of the carriers. In the example being described, the axes are inclined about 45" to the horizontal, but in principle it is possible to locate them at any inclination, as well as horizontally. In general, the closer to the horizontal the faster the selection mechanism can be operated, but accessibility to the mechanism may be compromised. At an inclination of between 300 and 600 to the vertical, preferably approximately 450, an effective compromise can be achieved between these two factors.

Each carrier is in the form of a slide bar 20 located in fixed guides 22, 24 near its opposite ends, to permit only axial displacement longitudinally of the carrier. Projecting beyond the forward end of each slide bar carrier and connected to that end by way of a leaf spring 29 is an entrainment device 28 in the form of a long, narrow bar. The entrainment bars 28 extend generally coaxially with their slide bars 20, but are connected thereto, by way of said leaf spring 29, so as to be spring biassed to a slightly downwardly deflected position, i.e. so as to have a rest position at a few degrees inclined down relative to the slide bar axis.

The manner of connection of the leaf spring 29 to the slide bar 20 and the entrainment bar 28 is shown in more detail in Figs. 2 and 3. In this respect, the leaf strip 29 is a substantially straight length of metal wire with curled end sections which are fitted into respective matching notches 17 formed in the facing ends of the bars 20, 28, and secured there by respective rivets, the shafts of which extend through the curled end sections of the spring 29. In this way, there is minimal lateral protrusion, constituted merely by the extent of the rivet flanges, at each side of the close packed bars 20, 28.

The ends of the bars 28 remote from the slide bars 20 rest, in the direction of bias, on a bridge 30 which extends laterally of the bars 28. Each entrainment bar 28 can be deflected upwards relative to its slide bar 20, and against the aforesaid spring bias of the leaf spring connection 29 to an angular position indicated in broken lines in Fig. 1. For this deflection each entrainment bar 28 has an individual solenoid 32 associated with it, the armature of which carries a plunger 34 which is displaceable by actuation of the solenoid to contact the underside of the bar 28.

Visible in Fig. 1 is a group of seven solenoids arranged in a staggered manner for successive entrainment strips because the solenoid width is greater than the pitch of the bars.

Each entrainment bar 28 is integrally formed with an upwardly projecting tooth 36 at one location along the side of the bar opposite to that contacted by the solenoid plunger. This tooth 36 is designed to cooperate with a toothed engagement member .38 in the form of a shoe having a toothed rack 40. Depending on the width of the loom there may be one engagement shoe 38 spanning all the entrainment bars 28 or a number of such shoes 38 disposed in parallel and moving in unison.

A single shoe will be referred to in the following for simplicity of description.

The engagement shoe 38 is bolted on to a carriage 42 which slides on a fixed guide 44 extending parallel to the slide bars 20. A drive lever, illustrated only fragmentarily, has one end located in a slot 48 in the carriage and its opposite end mounted on a fixed pivot.

A cam drive (not shown) reciprocates the shoe about the fixed pivot in synchronism with the movements of the grippers.

With the entrainment bars 28 in their full line spring biased position, they lie clear of the engagement shoe as it moves. By operation of the associated solenoid 32, each bar 28 is deflected upwards towards the engagement shoe 38 to insert its tooth 36 into the toothed rack 40 of the shoe 38 and the carrier 20 is then displaced with the engagement shoe. The solenoid is energised only momentarily, but immediately adjacent the forward ends of the entrainment bars 28 there is a series of fixed rests 50 in the form of individual spring blades for the respective bars.The upward deflection of a bar 28 lifts its end above the level of the rest 50 so that once the entrainment bar 28 has begun to move with the engagement shoe 38 and the solenoid 32 has been de-energised, its forward end overlies the rest 50, which then supports the bar 28 to maintain its tooth 36 engaged with the rack 38 for the remainder of the movement of the shoe 38. By the use of a resilient blade to provide this support, the speed of movement of the solenoid 32 is not critical since the blade can deflect if the bar 28 begins to be displaced by the engagement shoe 38 before it has been fully lifted. Furthermore the friction provided by the blade is sufficient to prevent any undesirable frictional entrainment of adjacent bars particularly where one is deflected by solenoid and the other is not.

The carrier tooth 36 is engageable with any of the seven teeth of the engagement shoe rack 40, depending upon when, during the stroke of the engagement shoe, the associated solenoid 32 is operated, and the carrier 20 will then move with the engagement shoe 38 through the remainder of its stroke. When the engagement shoe 38 reaches the end of its forward stroke, the grippers 10 are actuated to withdraw a yarn 12 from each carrier.

It will be seen that a particular yarn will be presented to each gripper in dependence upon the distance the associated carrier 20 has been displaced, and that this is determined by which tooth the engagement shoe rack 40 has been engaged by the entrainment bar tooth 36. The timed operation of each solenoid 32 thus allows the selection of any of seven yarns by the associated gripper. A further yarn selection position is provided by the undisplaced carrier, i.e. its solenoid remaining inactive.

The engagement shoe has a dwell at the end of its stroke to allow the required length of yarn to be drawn out and severed from the carrier, the gripper then introducing the severed yarn length into the shed.

The control means (not shown), which may comprise a microprocessor, operates the solenoids 32 in a programmed sequence so that by simple changes of program it is possible to bring the individual bars 28 into contact with the engagement shoe in any sequence to select the yarns for weaving an intended carpet pattern in the loom. It will be appreciated that pattern changes can be easily and quickly made by virtue of this method of control. Optical monitoring means (not shown) may be provided for the displacements of the carriers, their signals being inputted to the control means as a guard against malfunction.

The preferred form of the teeth 36, 40 illustrated includes bearing faces perpendicular to the direction of displacement of the carrier, so that a precise location of the yarn guides 16 can be ensured while allowing some tolerance in the angular displacement of the entrainment bars 28 whissle they are supported on their spring blades 50. The gaps between the rack teeth 40 are considerably wider than the entrainment bar tooth 36 so as to provide considerable latitude for the timing of the solenoid movements. It will be understood that the same function can be achieved if the entrainment strip has a series of teeth for cooperation with a single tooth on the engagement shoe, or indeed if each of these parts has a series of teeth.

The number of teeth and the number of yarns may, of course, vary compared to the illustrated embodiment of Fig. 1.

In a modified embodiment, as shown in Fig. 4, the entrainment bars 28 themselves are substituted by metal wires 128, which have a direct resilient, spring loaded connection to their respective carriers 20 and teeth 136 formed as kinks or joggles in the wire. The manner of connection of the wire 128 to the bar 20 is preferably substantially as shown in Fig. 3 and previously described.

In the embodiment illustrated in Fig. 5, the yarn carriers 60, as in the first example, are in the form of bars located in guides (not shown) which maintain them side-by-side whilst allowing them to side in their longitudinal directions as indicated by the double arrow 62. For the displacement of the carriers, there is now provided a rack and gear arrangement comprising, for each yarn carrier 60, a rack bar 64 connected at one end to the carrier by pre-tensioned leaf spring 66, again biassed slightly downwards as in the first example.

Between its ends, the bar 64 is formed with rack teeth 76 which face engagement means provided by a toothed quadrant 78 on a gear roll 80 mounted on a shaft 82 extending in fixed bearings transversely across the rack bars 64 of the carriers. Conveniently, the roll 80 is in axial sections registered with respective groups of rack bars and fixed together to rotate in unison. Drive means (not shown) operates in synchronism with the drive of the grippers 10, so that during each cycle of operation of the loom, the gear roll is turned firstly in a forward or anti-clockwise direction, and then subsequently in a reverse or clockwise direction, as indicated by the arrows 84.

The forward end 86 of the rack bar 64 is of reduced depth so as to define an inclined transition 88 on the bar. In the illustrated forward endmost position of the bar, this transition rests upon a support spindle 90 extending transversely across the loom and the rack teeth 76 are clear of the gear roll. Adjacent the spindle is a respective solenoid 32 disposed with its armature directed towards and carrying a plunger 34 aligned with the rack bar 64. Fig. 5 shows only one solenoid but the arrangement corresponds to that in the first example, and the solenoids for groups of successive bars will be arranged in staggered groups.

Also similarily to the first example, the solenoids are connected to a programmable control unit (not shown) to which is also connected optical monitoring means (not shown) for sensing the instantaneous position of each of the yarn carriers. In this case also, therefore small runs and frequent pattern or design changes are practical.

The mode of operation is similar to the first example. The rack bar 64 is illustrated in its forward endmost position, and if it is desired in a particular cycle for the first of the tufting yarns 12 to be selected, the solenoid 32 will remain unenergised.

Accordingly, the gripper 10 swings to the illustrated position and takes the first of the yarns 12 to introduce a short length cut therefrom into the shed as already described. The turning of the gear roll 80 as indicated by the arrows 84 has no effect on the rack bar and the yarn carrier because of the clearance between the har 64 and the gear roll.

If one of the other yarns 12 is required to be selected, the solenoid 32 is energised to extend its plunger 34 into contact with the rack bar 64 and cause the bar to be deflected at its leaf spring connection 66 so as to mesh the rack teeth 76 with the teeth of the quadrant 78. As a result, the rack bar is moved rearwardly (i.e. to the right as viewed in the drawing).

Only momentary energisation of the solenoid 32 is required, the rack bar 64 being held in engagement with the quadrant by the spindle 90 once it has begun to move forwards, until the gear roll has been turned to the limit of its movement. The control means, as in the first example, by timing the energisation of the solenoid in relation to the rotational stroke of the roll, will determine the amount by which the rack bar and carrier is displaced and hence which of the yarns is to be selected.After the gripper 10 has drawn off the selected yarn and the required yarn length has been cut, the gear roll 80 turns back in the clockwise direction and returns the rack bar 64 and the yarn carrier 62 to the illustrated starting position, the bias of the leaf spring 66 ensuring that the rack bar 64 is positively disengaged from the gear roll as it returns.

It will be understood that many of the features described in either of the examples above can be employed in the other. For example the toothing profiles of the engagement and entrainment means of Fig.

1 can be applied to the embodiment of Fig. 5 and vice versa. Also, the rack bar 64 and leaf spring 66 of the Fig. 5 embodiment can be replaced by a unitary wire or metal strip in comparable manner to the Fig. 4 modification.

Furthermore, these particular embodiments can be modified in many ways, within the scope of the present invention. Thus, in the described cases, an entrainment bar is connected to the engagement shoe or gear segment at a selected instant during displacement of the latter, and is entrained by the engagement member to the end of its movement; however, the arrangement could be such that each entrainment bar is initially connected to the engagement member and is only deflected so as to become disconnected from it when the respective yarn carrier has been brought to its selected position.

Also, whereas in the illustrated examples the solenoids are arranged to act directly upon their respective entrainment strips or bars, the arrangement may be such that respective pneumatic cylinders or rams, which may be actuated by respective solenoids, are extended to engage the entrainment strips or bars or equivalent components; such pneumatic devices may be more compact, at least in width, than the equivalent solenoids and therefore be more easily accommodated in the confined space that is available.

Claims (12)

CLAMS

1. fA gripper Axminster carpet loom in which each gripper has associated therewith a respective elongate yarn carrier having means for locating a plurality of yarns at intervals along its length, each carrier being axially displaceable to present a chosen yarn to an associated gripper according to the longitudinal position of the carrier, means for the axial movement of the carrier comprising an engagement device displaceable in sequence with the gripper and an associated entrainment device comprising an elongate member extending generally in the axial direction of its carrier and attached thereto by a resilient springloaded connection, one of said engagement and entrainment devices comprising a plurality of teeth and the other of said devices having at least one co-acting tooth wherewith said engagement and entrainment devices are ::releasably engageable with one another, and control means serving, during displacement of the engagement device, to effect engagement or disengagement of said devices by deflecting the elongate member against the spring bias of the connection so as to obtain selective longitudinal movement of the carrier to present a cornesponding selected yarn to the respective gripper.

2. EA loom according to claim 1 wherein the yarn carrier and the entrainment device are connected end to end.

3. A loom according to claim 1 or 2 wherein each entrainment device is connected to its carrier by a respective connection element in the form of leaf spring.

4. A loom according to claim 1 or 2 wherein each entrainment device comprises an elongate leaf spring connecting directly to its carrier.

5. A loom according to claim 4 wherein the teeth of the entrainment devices, for engagement with the engagement devices, are formed integrally as kinks or bent portions of the leaf springs, which are constituted by wires or metal strips.

6. A loom according to any preceding claim wherein each entrainment device effectively comprises a rack connected to the yarn carrier and deflectable laterally to engage with and disengage from the engagement device.

7. A loom according to claim 6 wherein the entrainment device and its carrier are arranged at an inclined angle, or else substantially horizontally, such that the entrainment device is spring biassed to a lower position and is deflectable upwardly to engage with the engagement device by intermeshing of the respective teeth.

8. A loom according to any preceding claim wherein the engagement device is in the form of a toothed sector or gear wheel which is rotated back and forth in synchronism with the operation of the gripper.

9. A loom according to any of claims 1 to 7 wherein the engagement device comprises a toothed element or rack which effects linear movement in synchronism with the operation of the gripper.

10. A loom according to claim 9 wherein the engagement device comprises a reciprocable shoe with rack teeth or a single tooth that extends laterally across a series of entrainment devices, and each entrainment device comprises, in the former case a single tooth or, in the latter case, a toothed rack.

11. A loom according to any preceding claim wherein connection of the entrainment device with the engagement device occurs during forward movement of the engagement device so that the carrier is entrained by the engagement device as the latter moves to an end position, from which it then returns to a starting or rest position.

12. A gripper Axminster carpet loom substantially as hereinbefore described with reference to and as illustrated by Fig. 1 or Fig. 5 of the accompanying drawings, or Fig. 1 or Fig. 5 as modified by Fig. 4 of the accompanying drawings.