GB1602226A - Thread return device for knitting machine - Google Patents

Description

(54) THREAD RETURN DEVICE FOR KNITTING MACHINE (71) We, EDOUARD DUBIED & CIE (SOC- ciete Anonyme), a Swiss company, of 2108 Couvet, Switzerland, do hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a thread return device for a knitting machine.

Return devices are already known which have given satisfaction for returning small amounts of thread or working only as thread tensioners.

In the majority of cases, the return or the tensioning of the thread are obtained by a flexible lever equipped with a thread eyelet at one end. When the tension exerted on the thread diminishes, said lever describes an arc of a circle and deflects the thread from its path until the equilibrium between the tension exerted on the thread and the return force of the lever is restored.

The recent developments in knitting machines have had as their object to increase the working speeds and the new knitting techniques tend towards obtain ing integral knitwear. Because of their conoeption, the conventional devices no longer suffice to return the thread sufficiently quickly, the inertia of the levers being too great. They do not have sufficient capacity to reutrn the lengths of thread required by the abrupt variations in the length of successive rows of loops, such as are imposed by said new knitting techniques.

The object of the invention is to eliminate the aforesaid disadvantages by creat ing a simple device, which can easily be fittted to the conventional knitting machines, enables the return lengths tor be increased within large proportions, works with a substantially constant tension and greatly reduces the jerks on the thread.

According to the present invention there is provided a thread return device for a knitting machine, comprising two spaced apart guides for the thread, a first element of small mass for engaging thread extending between the two guides, a highly resilient element secured to the first element, and control means for exerting a substantially constant force on said resilient element to withdraw the first element away from the thread guides so as to form a loop in thread extending between the guides when the thread is under a tension less than that exerted by said control means, the highly resilient element being adapted to permit small return movement of the thread during knitting operations of a machine fitted with the thread return device, and the control means permitting relatively large return movement of the thread.

Preferably, the element of small mass is a rigid wire, for example of steel or aluminium, which is shaped and comprises at least two thread-guiding ends, disposed one at each side of an attachment point to the highly resilient element, the two ends of the shaped rigid wire are hooks, and the highly resilient element consists of at least one wrapped elastomer.

Part of the highly resilient element may be wound around a wheel rotatably mounted in a frame of the device, and the control means comprises winding means arranged to exert a substantially constant torque on the wheel in the opposite direction to the direction of unwinding of the highly resilient element. The control means may include an adjusting spring enabling d;fferent magnitudes of the substantially constant torque to be selected.

The accompanying drawings illustrates, by way of example, one form of embodiment of the thread return device forming the subject of the invention: Figure 1 is a side view thereof, partially in section and comprises a diagram of the passage of the thread, Figure 2 is a view in elevation, partially in section and Figure 3 is a diagrammatic view, in the working position, Figure 4 is a view of an article which can be produced with this device.

The device shown in Figure 1 is drawn partially in section. The path along which the thread passes is very diagrammatic.

The thread 1 arrives from a conventional bobbin holder, not illustrated, only encountering on its passage conventional elements for stopping at knots and their accessories which will neither be described nor illustrated within the scope of this invention. The thread 1 passes through an eyelet 2, a thread tightener 3, an eyelet 4, a hook element 5 and a eyelet 6. The hook element 5 is illustrated in the position of maximum return. The thread tightener 3 is advantageously placed close to the eyelet 4 in order to avoid having to regulate the braking of the thread 1 depending on the eyelet 2, the other eyelets and the accessories not illustrated situated between the thread tightener and the thread bobbin. Thus the tension in the thread 1 between the thread tightener and the bobbin is very slight. The hook element 5 is of small mass, for example an aluminium wire, to limit its inertia to the maximum when it has to be displaced. It is advantageously provided with two open hooks 7, 8 to facilitiate its hooking to the thread 1.

A highly resilient element 9 is rigidly connected by one of its ends, to the element 5, at an attachment point 10. This highly resilient element 9 may advantageously be a resilient wire wrapped with a less resilient wire thus determining a maximum limit of elasticity. The hooks 7, 8 are advantageously disposed one at each side of the attachment point 10 to prevent the two strands 11, 12 of the thread 1 from becoming twisted when the thread is returned. The other end of the highly resilient element 9 is fixed in the groove 13 (Figure 2) of a wheel 14 rigidly connected to a spindle 15 turning freely in the walls 16, 17 of a return box 18. A non resilient wire 19 is fixed by one end in an opening 20 in the spindle 15, passes through a hook 21 rigidly connected to one end of a lever 22 and is fixed by its other end in an opening 23 in said spindle 15.

The lever 22 is rigidly connected to a spindle 24 accommodated for pivoting respectively in an aperture 25 in a wall 16 and an aperture 26 in a wall 17 of the return box 18. A spring 27 is attached by one of its ends 28 in the lever 22 and by its other end 29 to a spindle 30 which can be placed manually in one of the slots 31 formed in an upright 32 rigidly connected to a base 33 of the return box 18.

The return box 18 is rigidly connected to a support 34 situated at the ends of a knitting machine, by fixing means 35.

The highly resilient element 9 passes through the base 33 of the return box through a bush 36 rigidly connected to a bar 37 resting freely on said base 33. Said bar 33 is held laterally by guides 28, 39 (Figure 2). The bush 36 passes freely through the base 33 through an aperture 40. A switch 41 is rigidly connected to the wall 16 and its sensor 42 is in contact with the bar 37.

Figure 3 illustrates, in a highly diagrammatic manner, the return device in a knitting position, that is to say ready to work if the tension of the thread 1 drops. During the knitting, the thread 1 travels through the hooks 7, 8, but being very slightly deflected in its path.

The sensitivity of the device is adjustable by the position of the spindle 30 in one or the other of the slots 31. The spring 27 pulls on the lever 22 which itself tends to unwind the non-resilient wire 19 wound round the spindle 15 in such a manner that the wheel 14 tends to wind the resilient wire 9 on the wheel 14. Because of its resilience, the resilient wire 9 tensions the thread 1 by means of the hooks 7, 8.

When the knitting machine is stopped, the thread tightener 3 should be regulated and the spring 27 should be tensioned in such a manner as not to wi,thdraw the thread 1 from the bobbin and to guarantee a satisfactory return of the thread.

The device of Figure 1 is drawn in the position of maximum return, the nonresilient wire 19 being almost entirely unwound and the resilient wire being wound on the wheel 14.

On breakage of the thread 1, the hooks 7, 8 are no longer held and are returned by the return box 18 and the hooking element 5 strikes against the bush 36 which raises the bar 37. The bar raises the sensor 42 which causes the automatic electric stoppage of the knitting machine.

The device according to the invention is a particular advantage when the knitter wishes to make a cruciform article such as that illustrated in Figure 4, on a rectilinear knitting machine. The knitting begins with a rib 43, follwed by a front 44, sleeves 45, 46, a back 47 and a rib 48. It will easily be understood that a large amount of thread has to be returned when the knitting of the front 44 is finished and the sleeves 45, 46 have to be knitted or when the knitting of the sleeves is finished and the back 47 has to be knitted, and that the lengths of return imposed by this type of article can no longer be taken up by the conventional devices.

Thus the knitter has in his hands a device which is independent of the inertia of the winding mechanism and has a rapid reaction as a result of the resilience of the highly resilient element 9. This device like wise has a substantially constant tension because the variation in force in the resilient wire, caused by the reduction in its length, is compensated by a lever and spring system adapted to act with a substantially constant torque on the spindle 15 of the wheel 14.

Depending on the nature of the thread to be knitted, the hooking element 5 will tend to be displaced with the thread 1. A fork 49 is then advantageously disposed in the path of the thread 1, between the eyelet 6 and the hook 8, in such a manner as to limit the lateral displacement of the hooking element 5. The fork 49 is mounted for pivoting on a spindle 50 rigidly connected to a support 51, corresponding to the conventional support of the eyelet 6.

WHAT WE CLAIM IS: 1. A thread return device for a knitting machine, comprising two spaced apart guides for the thread, a first element of small mass for engaging thread extending between the two guides, a highly resilient element secured to the first element, and control means for exerting a substantially constant force on said resilient element to withdraw the first element away from the thread guides so as to form a loop in thread extending between the guides when the thread is under a tension less than that exerted by said control means, the highly resilient element being adapted to permit small return movement of the thread during knitting operations of a machine fitted with the thread return device, and the control means permitting relatively large return movement of the thread.

2. A device as claimed in claim 1, characterised in that the element of small mass is a rigid wire, for example of steel or aluminium, which is shaped and compricses at least two thread guiding ends, disposed one at each side of an attachment point to the highly resilient element.

3. A device as claimed in claim 2, characterised in that the two ends of the rigid shaped wire are hooks.

4. A device as claimed in any of claims 1-3, characterised in that the highly resilient element consists of at least one wrapped elastomer.

5. A device as claimed in any of claims 1-4, characterised in that part of the highly resilient element is wound around a wheel rotatably mounted in a means comprising winding means arranged to exert a substantially constant torque on the wheel in the opposite direction to the direction of unwinding of the highly rseilient element.

6. A device as claimed in claim 5, characterised in that the control means includes an adjustable spring enabling different magnitudes of the substantially constant torque to be selected.

7. A thread return device for a knitting machine, substantially as hereinbefore described with reference to the accompanying drawings.

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

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. wise has a substantially constant tension because the variation in force in the resilient wire, caused by the reduction in its length, is compensated by a lever and spring system adapted to act with a substantially constant torque on the spindle 15 of the wheel 14. Depending on the nature of the thread to be knitted, the hooking element 5 will tend to be displaced with the thread 1. A fork 49 is then advantageously disposed in the path of the thread 1, between the eyelet 6 and the hook 8, in such a manner as to limit the lateral displacement of the hooking element 5. The fork 49 is mounted for pivoting on a spindle 50 rigidly connected to a support 51, corresponding to the conventional support of the eyelet 6. WHAT WE CLAIM IS:

1. A thread return device for a knitting machine, comprising two spaced apart guides for the thread, a first element of small mass for engaging thread extending between the two guides, a highly resilient element secured to the first element, and control means for exerting a substantially constant force on said resilient element to withdraw the first element away from the thread guides so as to form a loop in thread extending between the guides when the thread is under a tension less than that exerted by said control means, the highly resilient element being adapted to permit small return movement of the thread during knitting operations of a machine fitted with the thread return device, and the control means permitting relatively large return movement of the thread.

2. A device as claimed in claim 1, characterised in that the element of small mass is a rigid wire, for example of steel or aluminium, which is shaped and compricses at least two thread guiding ends, disposed one at each side of an attachment point to the highly resilient element.

3. A device as claimed in claim 2, characterised in that the two ends of the rigid shaped wire are hooks.

4. A device as claimed in any of claims 1-3, characterised in that the highly resilient element consists of at least one wrapped elastomer.

5. A device as claimed in any of claims 1-4, characterised in that part of the highly resilient element is wound around a wheel rotatably mounted in a means comprising winding means arranged to exert a substantially constant torque on the wheel in the opposite direction to the direction of unwinding of the highly rseilient element.

6. A device as claimed in claim 5, characterised in that the control means includes an adjustable spring enabling different magnitudes of the substantially constant torque to be selected.

7. A thread return device for a knitting machine, substantially as hereinbefore described with reference to the accompanying drawings.