Continuous, flexible thread-like materials are used in many manufacturing processes, such as those in the textile, clothing, rope-making and wire-making industries. Such materials, either of natural origin or of synthetic origin, are variously known as fibers, filaments, yarns or threads, depending upon the industry in which they are used. These materials are generically referred to as"threads"in this specification.

For the convenience of packaging, storage, transport and further use, threads are commonly cross-wound under tension into packages of conical or cylindrical shape, and when used in a further process, the threads may conveniently be withdrawn over-end from the packages in a direction parallel to the axis of the package, either continuously or intermittently.

Many manufacturing processes require the thread to be withdrawn from the package in a highly controlled way and at low tension to ensure consistent uptake of the thread in the next processing stage, but variations in thread tension may arise as the instantaneous point of unwinding from the package moves continuously across the package surface as a consequence of the form in which the package was wound. Such variations in thread tension may disturb the manufacturing process and result in undesirable variations in the end product.

Some threads, such as spun yarns and textured continuous filaments, may exhibit a residual torque due to the twist in the threads, which may cause the thread to twist upon itself into a snarl, under low tension. Snarls formed in this way may persist into the final product as a fault or blemish on a product produced from the thread.

Various devices have been designed to correct such snarls in a running thread, but generally produce an undesirable increase in thread tension, and do not exercise any control over the way in which the thread unwinds from the package. Other devices are known, which do control the way in which the thread unwinds from the package, such as an elastic net sheath on the package, or a weighted friction ring arranged along the axis of the package, but such devices are not restrained from moving along the package axis and thus may lead to unstable withdrawal conditions, and in the case of elastic net sheaths, they may be gradually pulled off the packages by the friction of the withdrawn threads. A further limitation of these devices is that they can only be applied to machines and processes in which threads are withdrawn in a vertically upward direction. Such devices are sometimes inconvenient to use in industrial conditions.

A further problem may arise when withdrawing thread at low tension, which is sloughing-off of the outer layers of coils from the package. This occurs primarily with low friction threads, which have been wound tightly into a package with parallel wind. With such packages, the low tension may transmit to the coils on the package, allowing the coil tension to fall and coils to slip, or be pulled over one another and create a tangle.

This interrupts the processing and results in waste. This problem can be avoided by maintaining a minimum tension of withdrawal and eliminating fluctuations in tension.

An object of the present invention is to provide a tensioning method and device which employs a nipping action to provide consistent and low thread tension between the point of unwinding from a package and the point at which the thread is used in a manufacturing process, the thread tension being high enough to prevent the formation of snarls and sloughing of coils of thread from the package, and low and consistent enough to suit usage of the thread in a downstream process.

A further object of the present invention is to provide a tensioning method and apparatus which provide consistent and low thread tension irrespective of the direction of withdrawal.

According to a first and broadest aspect of the invention there is provided a method of tensioning a textile thread and the like during processing, the method including the step

of employing a nipping action, i. e. a gentle restraining action, to provide consistent and low thread tension between the point of unwinding from a package and the point at which the thread is used in a manufacturing process.

With a device as mentioned above according to the present invention the objects listed before are met by a device comprising nipping means having: a) a generally circular tensioning device arranged c-axial with respect to the package and having a circumferentially running track groove; and b) a ring being arranged in said track groove with an inner diameter of the ring being larger than an inner diameter of the track groove, but smaller than an outer diameter of the track groove, thus allowing the ring to move within said track groove to form a gap for the thread to pass between an inside area of the ring and the track groove.

According to a further proposal of the invention the tensioning device may be an integral part of the package former, i. e. a yarn carrier, or it may be detachably fixed to such a former.

Furthermore the invention suggests that the track groove may be U-shaped in cross section. Moreover it may be advantageous that the track groove profile is tapered at least on one of its sides.

According to another proposa of the invention the ring may be formed open with overlapping ends thus providing a complete inner surface against the thread.

Further the invention suggests that the tensioning device may be made from plastic, steel or ceramic.

To avoid any catching or snagging of the thread the invention provides that at least within the region coming in contact with the thread the ring and the track groove may be polished free from any surface roughness or blemishes.

Furthermore the invention suggests that at least the surface of the ring is coated. Finally the invention is directed to a package former, i. e. a yarn carrier, to which a device for controlling as described above is detachably fixed or an integral part.

Further aspects of the invention which should be considered in all its novel aspects will become apparent from the following description which is given by way of example only.

Examples of the invention will now be described with reference to the accompanying diagrammatic drawings in which: Figure 1 depicts in cross-section a circular ring and track tensioning device mounted at one end of a package center, a cylindrical package and a thread being withdrawn through the tensioning device ; Figure 2 depicts in plan a circular closed ring and track tensioning device, which is sectioned through the plane I-I shown in Figure 1; Figure 3 depicts in plan (Figure 3a) and in side view (Figure 3b) one design of open ring; and Figure 4 depicts in cross-section two profiles of a track way which might be incorporated in the tensioning device.

Referring now to Figure 1, the thread 1 is withdrawn from the package 4 and passes through a clearance gap between the ring 2 and the track 3 and onto a thread guide 6 fixed at a distance from, and on the axis of the package 4. The ring 2 may be made from plastic, steel, ceramic or any other suitable material, and is dimensioned so that it may be sprung onto the track 3 but retained between the shoulders of the track 3 with a small clearance between the inside diameter of the ring and the diameter of the track groove. The ring 2 and the track 3 are polished free from any surface roughness or blemishes which could cause the thread 1 to catch or snag on their surfaces. The ring 2 is dimensioned to provide a nip between the ring 2 and track 3 sufficient to allow the thread 1 to slip between the ring 2 and track 3 under the desired withdrawal tension.

In operation when the thread 1 is withdrawn from the package 4 through the clearance gap between the ring 2 and the track 3, the ring 2, together with the track 3, provides a nip which exerts a retarding force on the thread 1. The running thread 1 rotates in a balloon around the package 4 and the track 3 as it is withdrawn, and the ring 2 continuously adjusts its position and attitude to accommodate the thread 1. The ring and track tensioning device provides a consistent and even tension downstream in the thread 1. The thread 1 is also tensioned by the friction drag over the surface of the package 4 as it is withdrawn. The nipping action between the ring 2 and track 3 prevents thread 1 from momentary slackening and eliminates the formation of snarls in the downstream thread. In the event that withdrawal of the thread 1 stops (e. g., processing stops) or slows down suddenly and the downstream tension falls to near zero, the nip between the ring 2 and thread 1 and track 3 blocks the fall in tension from transmitting upstream of the tensioning device and so prevents coils on the package 4 from slackening and the coils sloughing off.

Referring now to Figure 2, the ring 2 may run in the track 3 so that the clearance gap 8 between the ring and the track 3 follows the thread 1 as it circulates around the track 3 whilst the diagonally opposite end of the ring 2 runs at the smallest outer radius 7 of the track 3. The track 3 may be made from plastic, steel, ceramic or any other suitable material.

Referring now to Figure 3a and Figure 3b, the ring 2 may be formed open with overlapping ends to provide a complete inner surface against which the thread 1 runs, and an open gap 9 through which the thread 1 may be conveniently threaded. The ring 2 may be made from steel, ceramic or any other suitable material, and may be coated or surface-finished with suitable known materials to enhance running performance and durability.

Referring now to Figure 4a and Figure 4b, the track way of track 3 may be profile to either circular slit, or tapered, or any other suitable geometrical shape, to suit the shape, dimension, orientation, and conditions of specific thread package.

Where in the description particular integers are mentioned it is envisaged that their equivalents are incorporated as if they were individually set forth herein.

By this invention there is provided a method and apparatus for ensuring constant and uniform tension in thread withdrawn over end from a package. It is envisaged that modifications and variations in the design of this apparatus can take place without departing from the scope and spirit of the invention.