GB2216553A

GB2216553A - Tufting machine yarn feed control system

Info

Publication number: GB2216553A
Application number: GB8905516A
Authority: GB
Inventors: Douglas George Woodcock
Original assignee: PICKERING STAPLINA Ltd
Current assignee: PICKERING STAPLINA Ltd
Priority date: 1988-03-14
Filing date: 1989-03-10
Publication date: 1989-10-11
Also published as: GB8905516D0; GB8805964D0

Abstract

Yarn (50) is fed to the needles (12) of a tufting machine by way of a driven roller (36), which can be driven selectively at slow or fast speeds by a clutch mechanism (40) so as to produce patterns of short/long tuft length, or in the case of a machine where the needle bar (10) is longitudinally displaced (arrow 20) so as to compensate for such sidewise movement and provide even tuft length. Changeover of the clutch from slow to fast speed is effected in each case by movement of a mechanical actuator (e.g. 42, 44) past a sensor or proximity switch (46). Where the needle bar (10) is displaceable the actuator (42, 44) is preferably associated with the displacement mechanism, e.g. mounted on a cam (22) which controls the displacement sequence, so that yarn feed is synchronised therewith. Alternatively the actuator may be associated with the needle bar vertical reciprocation mechanism, or a fabric displacement mechanism (if present). <IMAGE>

Description

TUFTING MACHINE YARN FEED CONTROL SYSTEM This invention concerns a tufting machine, that is to say a machine of a kind comprising a plurality of needles to which tufting yarn is fed, carried by a needle bar which is adapted to be reciprocated parallel to the axes of the needles for the latter to penetrate a backing fabric to introduce tufts into the latter.

The invention is more particularly concerned with the control of feeding yarn to the needles in the aforesaid kind of tufting machine, optionally in conjunction with axial displacement of the needle bar.

Traditionally the needle bar only moves substantially vertically. However, tufting machines are known in which the needle bar is also controlledly displaceable in its own longitudinal (axial) direction, that is to say substantially horizontally, and transversely of the fabric being worked upon, and of the direction of movement of the fabric past the needle bar. Imparting such horizontal movement to the needle bar allows creation of tufting patterns, e.g. of zig zag, indented or like configuration, upon the fabric, or dispersion of yarn streaks.

In conventional level pile tufting machines the yarn is fed to the needles at a constant speed by yarn feed rollers such that horizontal displacement of the needle bar, known as side stepping, causes the stitches to become either longer or shorter, depending on the direction of displacement. This results in robbing or lengthening of the yarn which forms the pile and gives an undesired effect of vertical pile troughs and hills.

In some cases, however, it may actually be desirable to provide patterned effects in the finished product by controlledly creating areas of high and low tufts, unrelated to side stepping of the needlebar.

An object of the present invention is to provide, in a tufting machine of the kind referred to above, an improved yarn feed control system which allows yarn to be fed to the needles in an adjustable manner. The purpose, in a machine having an axially displaceable needle bar, is primarily to compensate for side stepping and overcome the problems of robbing and lengthening yarns as described above. More generally, the purpose is to enable control of tuft length.

With these objects in view, the invention provides a tufting machine comprising an elongate needle-carrying bar, a mechanism for reciprocation of the needle bar parallel to the axes of the needles so that the needles penetrate a fabric being worked upon, and driven clutch-controlled means for feeding yarn to the needles selectively at slow or fast speeds, characterised in that a mechanical actuator is provided which moves past a sensor or proximity switch to effect changeover of the clutch from fast to slow speed or vice versa In a machine where the needle bar is not axially displaceable and the yarn feed control system is used purely for tuft length patterning the actuator may be rotatable and may be associated with the reciprocation mechanism, e.g. by way of intervening gears, so that a predetermined pattern can be generated by the speed change of the yarn feed being in synchronism with the movement of the needles.

In contrast, in a tufting machine where the needle bar is displaceable in its own longitudinal (axial) direction, the yarn feed control system is primarily used to compensate for yarn lengthening or robbing upon needle-bar displacement, though may additionally be used for pattern generation. In this case, the mechanical actuator is advantageously associated with the needle bar displacement mechanism so that the speed change of the yarn feed is in synchronism with transverse displacement of the needle bar.

In this respect, the actuator is preferably a rotatable member mounted on a control cam which determines the displacement of the needle bar during one pattern sequence, which may consist of a single stitch or several stitches.

Such a rotatable member may consist of a flag or like means attached to the control cam. Indeed there may be several such flags or like means mounted at predetermined angular positions on the cam. More conveniently such a rotatable member may consist of a disc, which is coaxially mounted on the control cam and carries one or more flags or like means which influence the sensor or proximity switch.

Alternatively, where displacement of the needle bar is effected by interengaging screw-threaded elements, one of which is mounted on a shaft of an electric motor, the actuator may bearotatable member mounted on this same shaft. Again, the member may consist of a flag, or several flags or like means or of a disc carrying such means.

Yet another alternative is that displacement of the needle bar may be effected hydraulically e.g. by a piston and cylinder arrangement, in which case the actuator may be mounted on the piston or hydraulic ram.

Naturally, the invention is equally applicable to a tufting machine having multiple needle bars as to a machine having a single needle bar.

The invention will be described further, by way of example with reference to the accompanying drawing, in which the single figure is a schematic perspective illustration of the needle bar displacement mechanism and yarn feed control system of a preferred embodiment of tufting machine in accordance with the invention.

The illustrated embodiment of the tufting machine of the invention comprises an elongate needle bar 10 carrying a multitude of downwardly protecting needles 12 each of which is fed with tufting yarn 50, as shown only schematically by a broken line, from a creel or beams (not shown). The needle bar 10 extends in a substantially horizontal plane and is connected to the lower ends of plurality of perpendicular rods 14, only one of which is illustrated, by means of which it is vertically reciprocated, as indicated by arrows 16. Such reciprocation may be achieved by the upper ends of the rods 14 being connect to a rotating shaft, arranged parallel to the needle bar 10, by means of eccentrics. However, as details of the vertical reciprocation mechanism are not important to the present invention, these latter are not shown.As the needle bar 10 is reciprocated vertically the needles 12 are caused to penetrate a backing fabric, indicated schematically and only partially at 18, and produce tufts therein, which form the pile of a carpet.

The needle bar 10 is also displaceable in its own longitudinal or axial direction, as indicated by the arrow 20, by means of a control cam 22. In this respect, the bar 10 is connected to the rods 14 in a manner which allow it to slide axially relative thereto. The cam 22 is rotatably driven from a motor shaft 24 by way of a gear box 26. An elongate displacement element 28 extends from the cam 22 and lateral projections 30 provided at the nearest end of the needle bar 10 engage into an elongate vertically extending slot provided near the end of the element 28.

This element 28 also carries a dog 32 which is urged into contact with the cam surface by spring biasing means (not shown) acting on the element 28.

A the cam 22 rotates the dog 32 is acted upon by the cam surface so that the element 28, on which the dog 32 is mounted, moves to and fro displacing the needle bar transversely of the fabric 18. The cam surface obviously determines the sequence of axial displacement of the needle bar 10 during one pattern cycle which consists of a predetermined member of stitches or stitch rows e.g. four, six, eight. In other words the cam 22 rotates once per pattern cycle.

The yarn 50 is conducted around a pair of parallel yarn feed rollers 34,36 one of which 36 is driven from the same motor shaft 24 as the cam 22 by way of a variable speed gear box 38 and a clutch mechanism 40. This driven roller 36 serves to draw yarn 50 from the creel or beams and feed it positively to the needles 12. The clutch mechanism 40 is constructed such that the roller 36 can be driven selectively, at two different speeds, fast and slow the exact speeds being determined prior to operation of the machine by adjustment of the gear box 38.

The unique feature of the yarn feed control system of the invention is that the rate of yarn feed can be changed from fast to slow and vice versa by means of a mechanical actuator. In this particular embodiment the actuator is in the form of a disc 42 which is mounted co-axially on the cam 22 for rotation in unison therewith. A plurality of metal flags 44 are arranged at predetermined angular positions around the circumference of this disc 42. As the disc 42 rotates, these flags 44 pass, in turn, adjacent a proximity switch 46, which is connected to the clutch mechanism 40 by way of relays 48. Thus, as each flag 44 passes switch 46 the clutch is shifted and the speed of the yarn feed roller 36 correspondingly changes from fast to slow or vice versa.

The positions of the flags 44 on the disc 42 are selected to correspond to appropriate positions on the surface of the cam 22 so that the change of speed of the yarn feed is synchronised with transverse displacement of the needle bar 10. In this way the yarn feed can be made to compensate for the shift of the needle bar 10 so as to ensure that there is no lengthening or shortening of the pile (i.e. it remains even) when this occurs.

As mentioned in the introduction hereto, the aforesaid yarn feed control system can be adapted to specifically provide for variation in pile length when this is required as a patterning feature.

Naturally the invention is not limited to the precise details of the illustrated embodiment and many variations are possible, for example as mentioned in the introduction. It should be noted in particular that the invention can also be applied to tufting machines in which the needle bar is not axially displaceable, e.g. by sychronism of variation in yarn feed with vertical reciprocation of the needle bar, or to tufting machines in which the backing fabric is transversely displaceable instead of the needle bar. In the latter case, the variation in yarn feed can be synchronised with movement of the fabric.

Claims

1. A tufting machine comprising an elongate needlecarrying bar, a mechanism for reciprocation of the needle bar parallel to the axes of the needles so that the needles penetrate a fabric being worked upon, and driven clutch-controlled means for feeding yarn to the needles selectively at slow or fast speeds, characterised in that a mechanical actuator is provided which moves past a sensor or proximity switch to effect changeover of the clutch from fast to slow speed or vice versa.

2. A machine as claimed in claim 1 wherein the mechanical actuator is associated with the needle bar reciprocation mechanism so that a predetermined tuft length is generated by the speed change of the yarn feed being in synchronism with the movement of the needles.

3. A machine as claimed in claim 1 wherein the needle bar is displaceable in its own longitudinal (axial) direction, and the mechanical actuator is associated with the needle bar displacement mechanism so that the speed change of the yarn feed is in synchronism with transverse displacement of the needle bar.

4. A machine as claimed in claim 3 wherein the actuator is a rotatable member mounted on a control cam which determines the displacement of the needle bar during one pattern sequence, which may consist of a single stitch or several stitches.

5. A machine as claimed in claim 4 wherein the rotatable member consists of a flag or like means attached to the control cam.

6. A machine as claimed in claim 4 wherein the rotatable member consists of a disc, which is mounted on the control cam and carries one or more flags or like means which influence the sensor or proximity switch.

7. A machine as claimed in claim 3 wherein displacement of the needle bar is effected by interengaging screwthreaded elements, one of which is mounted on a shaft of an electric motor and the actuator is a rotatable member mounted on this same shaft.

8. A machine as claimed in claim 7 wherein the rotatable member consists of a flag or like means, or of a disc carrying one or more flags.

9. A machine as claimed in claim 3 wherein displacement of the needle bar is effected hydraulically by a piston and cylinder arrangement and the actuator is mounted on the piston or hydraulic ram.

10. A tufting machine having a yarn feed control mechanism substantially as hereinbefore described with reference to and as illustrated by the accompanying drawing.