GB2186297A - Improvements in or relating to tufting machines - Google Patents

Abstract

The invention proposes that the yarn feed to the needles of a tufting machine provide an amount of yarn appropriate to the insertion of a diagonal back stitch such as arises on lateral shift of a tufting needle relative to a backing fabric during the tufting operation. Various arrangements are disclosed, including one involving driving the yarn feed roller 11 at a requisite one of a range of possible speeds by coupling the said roller (11) to a drive shaft (12) by a drive transmission including a selected one of two drive coupling means (15, 16) of different respective gearing ratios. Others involve a variable speed motor, a yarn brake or a yarn constant tension device used in conjunction with a conventional jerker system. <IMAGE>

Description

being fed and by the extent of any such shift as occurs. The motor 22 is controlled according to patterning requirements to give a rate of yarn feed appropriate to a straight stitch or a diagonal stitch, consistent with a lateral shift of a single or multiple needle pitch.

The Fig. 3 embodiment provides that the yarn 31 is fed from a supply 32 thereof through a constant tension device 33 to the needle 34, there being a conventional jerker system 35 adjacent the needle and through which the yarn 31 passes. With such an arrangement the yarn requirement will be automatically met irrespective of the extent of lateral needle shift.

If desired, the arrangement shown in Fig. 3 may also include a yarn brake 36 selectively operable in timed sequence with the stitching cycle to provide a jerk in and/or pull back of the yarn.

In a still further arrangement, see now Fig.

4, the yarn 41 passes over a pair of undriven rollers 42 in moving to the tufting machine needle 43, the rollers 42 being subjected to controlled braking during upstroke of the needle to introduce a jerk/pull-back.

In a final embodiment, see Fig. 5, an individual yarn brake 51 is provided in relation to each needle, the operation of the yarn brake 51 being timed by reference to the presence or otherwise and to the extent of any lateral shift of the needle 52.

By selecting and providing the correct quantity of yarn for each stitch, according to whether the back stitch is "straight'' or "diagonal" it is possible to avoid a Barré effect and thus achieve a more level carpet surface than has hitherto been the case. Furthermore, we are able to reduce the likelihood of problems arising due to needles being held in positions out of optimum alignment with a corresponding hook/looper with which the same is to cooperate, such misalignment resulting from excessive yarn tensions and militating against proper needle/hook cooperation and satisfactory loop pick-up.

CLAIMS 1. In or for a tufting machine having laterally shiftable needles and a control mechanism adapted to effect such shift according to a predetermined sequence, a yarn feed arrangement operable in synchronism with the said control mechanism, said yarn feed arrangement providing a variable rate of yarn feed adapted to accommodate changes in yarn requirements arising from lateral needle shift.

2. A yarn feed arrangement as claimed in claim 1, including clutch-controlled feed rollers programmed to be driven at a selected one of a plurality of speeds according to a pattern sequence.

3. A yarn feed arrangement as claimed in claim 1, including an individual tension control against the restraint of which yarn is drawn from a supply thereof by needle reciprocation.

4. A yarn feed arrangement as claimed in claim 3, further including clamping means operable in timed relationship with the machine cycle, to provide a jerk in and/or pull back of the yarn.

5. A yarn feed arrangement as claimed in claim 4, wherein the clamping means is embodied in the tension control.

6. A yarn feed arrangement as claimed in claim 1, including a roller intermediate the needle and yarn supply and across which the said yarn passes in moving to the needle, the roller being adapted to be selectively braked during the upstroke of the needle to introduce a jerk and/or pull back to tighten an inserted loop.

7. A yarn feed arrangement as hereinbefore described with reference to and as illustrated in the various figures of the accompanying drawings.

SPECIFICATION Improvements in or relating to tufting machines The invention concerns tufting machines, and has more particular reference to yarn feed arrangements therefor.

In the manufacture of tufted fabrics on a tufting machine comprising a multiplicity of reciprocable needles and a corresponding multiplicity of hooks or loopers selectively cooperable with respective ones of the said needles, the needles and hooks or loopers being provided on opposite sides of a backing fabric and the needles penetrating such backing fabric to cooperate with respective hooks or loopers in forming loops at the reverse of such fabric, it is known to shift the needles laterally for patterning or other purposes, the needles, in such circumstances, moving to a position for cooperation with a different respective hook/looper from those with which the needles previously cooperated.

In the absence of lateral needle shift, each needle introduces a line of tufts which extends in the longitudinal direction of the backing fabric, the back stitch which exists at the needle side of the backing fabric between successive needle penetrations, and thus between successive yarn tufts, defining a sensible continuous straight line parallel to the direction of fabric movement.

In the event of a lateral shift of the needle between successive needle penetrations, the resultant back stitch will extend in a direction which is inclined to the direction of fabric movement, and, assuming, as is the case, that the rate of advance of the backing fabric remains constant, the length of the individual backstitch will be increased accordingly.

The drive to the yarn feed system of a tufting machine is traditionally by means of a chain and sprocket, a toothed belt or Vee belt drive and gearbox from the mainshaft of the tufting machine, equal angles of rotation of the machine mainshaft producing equal angles of rotation of the yarn feed rollers.

Such a direct drive yarn feed roller system cannot accommodate the changes in yarn feed requirement arising from lateral needle shift and may give rise to a Barré effect on the front face of the fabric. A further consequence is that, due to varying yarn tension, difficulty may be experienced in attaining accurate needle/hook or looper alignment and satisfactory loop take-up.

The object of the present invention is to provide a tufting machine wherein the adverse effects of changed yarn requirements arising from lateral needle shift are minimised or avoided.

According to the present invention there is proposed, in or for a tufting machine having laterally shiftable needles and a control mechanism adapted to effect such shift according to a predetermined sequence, a yarn feed arrangement operable in synchronism with the said control mechanism, said yarn feed arrangement providing a variable rate of yarn feed adapted to accommodate changes in yarn requirements arising from lateral needle shift.

The yarn may be delivered by clutch-controlled feed rollers programmed, in conjunction with patterning requirements, to be driven at a selected one of a plurality of speeds.

Thus changes in yarn feed rate will be made according to the lateral shift of the needle, yarn feed being programmed to accord with a patterning sequence which gives rise to a diagonal back stitch and any yarn feed variation being repeated with each pattern repeat.

In a further proposed arrangement the yarn is drawn freely from a supply thereof by the needle and is subjected to an individual tension control, and may be additionally clamped in timed relationship with the machine cycle to provide a jerk in and/or pull back of the yarn.

In a still further arrangement yarn is freely drawn from a continuous supply thereof by the needle according to requirements, a roller over which the yarn passes in moving to the needle being braked or not during the upstroke of the needle, the effect of the roller, in the former case being to introduce a jerk and/or pull back, thus to tighten the inserted loop.

The invention will now be described further, by reference to the accompanying diagrammatic drawings the individual figures of which respectively illustrate five different embodiments thereof.

In the embodiment shown in Fig. 1, a yarn feed roller 11 is fed at a selected one of a number of possible speeds from an input shaft 12 via a lay-shaft 13 and gear box 14, there being plural selectively operable drive connections 15, 16 between input shaft 12 and lay-shaft 13 of respective and different drive ratios. Each drive connection 15, 16 comprises a respective clutch 17, 18 mounted on the lay-shaft 13, energisation of a selected one of said clutches 17, 18, as determined by pattern requirements, serving to transmit a drive from input shaft 12 to the input sprocket 19 of gear box 14 according to the drive ratio of the drive connection 15, 16 of which the selected clutch forms a part.

The number of drive connections may, of course, exceed the two drive connections shown as would be necessary, for example, if lateral needle shaft of different increments were involved.

Fig. 2 illustrates an arrangement wherein the yarn feed roller 21 is driven by a variable speed motor 22 (or a stepping motor) via a gear box 23, the motion derived from the motor 22 being determined by the lateral shift or otherwise of the needle to which the yarn is

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (1)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   SPECIFICATION Improvements in or relating to tufting machines The invention concerns tufting machines, and has more particular reference to yarn feed arrangements therefor.

   In the manufacture of tufted fabrics on a tufting machine comprising a multiplicity of reciprocable needles and a corresponding multiplicity of hooks or loopers selectively cooperable with respective ones of the said needles, the needles and hooks or loopers being provided on opposite sides of a backing fabric and the needles penetrating such backing fabric to cooperate with respective hooks or loopers in forming loops at the reverse of such fabric, it is known to shift the needles laterally for patterning or other purposes, the needles, in such circumstances, moving to a position for cooperation with a different respective hook/looper from those with which the needles previously cooperated.

   In the absence of lateral needle shift, each needle introduces a line of tufts which extends in the longitudinal direction of the backing fabric, the back stitch which exists at the needle side of the backing fabric between successive needle penetrations, and thus between successive yarn tufts, defining a sensible continuous straight line parallel to the direction of fabric movement.

   In the event of a lateral shift of the needle between successive needle penetrations, the resultant back stitch will extend in a direction which is inclined to the direction of fabric movement, and, assuming, as is the case, that the rate of advance of the backing fabric remains constant, the length of the individual backstitch will be increased accordingly.

   The drive to the yarn feed system of a tufting machine is traditionally by means of a chain and sprocket, a toothed belt or Vee belt drive and gearbox from the mainshaft of the tufting machine, equal angles of rotation of the machine mainshaft producing equal angles of rotation of the yarn feed rollers.

   Such a direct drive yarn feed roller system cannot accommodate the changes in yarn feed requirement arising from lateral needle shift and may give rise to a Barré effect on the front face of the fabric. A further consequence is that, due to varying yarn tension, difficulty may be experienced in attaining accurate needle/hook or looper alignment and satisfactory loop take-up.

   The object of the present invention is to provide a tufting machine wherein the adverse effects of changed yarn requirements arising from lateral needle shift are minimised or avoided.

   According to the present invention there is proposed, in or for a tufting machine having laterally shiftable needles and a control mechanism adapted to effect such shift according to a predetermined sequence, a yarn feed arrangement operable in synchronism with the said control mechanism, said yarn feed arrangement providing a variable rate of yarn feed adapted to accommodate changes in yarn requirements arising from lateral needle shift.

   The yarn may be delivered by clutch-controlled feed rollers programmed, in conjunction with patterning requirements, to be driven at a selected one of a plurality of speeds.

   Thus changes in yarn feed rate will be made according to the lateral shift of the needle, yarn feed being programmed to accord with a patterning sequence which gives rise to a diagonal back stitch and any yarn feed variation being repeated with each pattern repeat.

   In a further proposed arrangement the yarn is drawn freely from a supply thereof by the needle and is subjected to an individual tension control, and may be additionally clamped in timed relationship with the machine cycle to provide a jerk in and/or pull back of the yarn.

   In a still further arrangement yarn is freely drawn from a continuous supply thereof by the needle according to requirements, a roller over which the yarn passes in moving to the needle being braked or not during the upstroke of the needle, the effect of the roller, in the former case being to introduce a jerk and/or pull back, thus to tighten the inserted loop.

   The invention will now be described further, by reference to the accompanying diagrammatic drawings the individual figures of which respectively illustrate five different embodiments thereof.

   In the embodiment shown in Fig. 1, a yarn feed roller 11 is fed at a selected one of a number of possible speeds from an input shaft 12 via a lay-shaft 13 and gear box 14, there being plural selectively operable drive connections 15, 16 between input shaft 12 and lay-shaft 13 of respective and different drive ratios. Each drive connection 15, 16 comprises a respective clutch 17, 18 mounted on the lay-shaft 13, energisation of a selected one of said clutches 17, 18, as determined by pattern requirements, serving to transmit a drive from input shaft 12 to the input sprocket 19 of gear box 14 according to the drive ratio of the drive connection 15, 16 of which the selected clutch forms a part.

   The number of drive connections may, of course, exceed the two drive connections shown as would be necessary, for example, if lateral needle shaft of different increments were involved.

   Fig. 2 illustrates an arrangement wherein the yarn feed roller 21 is driven by a variable speed motor 22 (or a stepping motor) via a gear box 23, the motion derived from the motor 22 being determined by the lateral shift or otherwise of the needle to which the yarn is