Rings in Ring Spinning System - How it works?

The Form Of The Ring:
Basic Forms: These are classified into:

Lubricated rings (in woollen and worsted spinning),
Unlubricated rings.
The standard ring of the short staple spinning mill the unlubricated type, can be considered under the headings:
- Single sided rings,
- Double sided rings.
For rings used in the short — staple spinning mill two dimensions are of prime importance; the internal diameter and the flange width.
 

The anti – wedge ring:
This was the first high performance ring. Compared with the previouslystandard ring form, it exhibits on enlarged flange inner side and is markedly flattened on its upper surface. This change of form permitted use of travelers with a lower center of gravity and precisely adapted bow (elliptical travelers), which in turn allowed operation at higher speeds. Anti  wedge rings and elliptical travelers belong together and can be used only in combination.

The low crown ring (conventional ring):
In the low crown ring, the curvature of the surface has been somewhat flattened compared with rings used up to that time. This gives more space for the passage of the yarn so that the curvature of the traveler can also be reduced (oval, flat travelers) and the center of gravity is lowered. In comparison with the anti wedge ring, the low  crown ring has the  advantages that the space provided for passage of the yarn is larger and that all current traveler shapes can be applied with the exception of the elliptical traveler. Today it is the most widely used ring form.

SU ring:
It has two advantages, namely a large surface of contact for the traveler on the inner flange (with correspondingly good heat transfer to the ring) and a degree of compensation of forces acting on the traveler. SU rings with corresponding travelers permit higher traveler speeds, especially with synthetic fibers and give a slight reduction in traveler wear.

Materials for the ring:
The ring should always be tough and hard on its exterior. The running surface in particular deserves the closest attention. The surface layer must have high and even hardness. The traveler hardness should be lower so that wear occurs mainly on the travelers, which is easier to replace and cheaper. Surface smoothness is also important. The following materials are used:
- Flame, or induction, hardened steel, to some extent,
- Nitrided steel,
- Carbo — nitrided steel (this is the most common)
- Chrome steel (this is found more rarely).
A good ring should have the following features:
1. Best quality raw material,
2. Good, but not too high, surface smoothness,
3. Exact roundness,
4. Good, even surface hardness, higher than that of the traveler,
5. It should have been run in as well as possible
6. Long operating lifetime,
7. Correct relationship between ring and bobbin diameter (2:1 up to 2,2:1),
8. It should be exactly centered relative to the spindle.
THE TRAVELLER

Task and Function:
The traveler imparts twist to the yarn, and enables winding of the yarn on the cop. The speed difference is due to lagging of the traveler relative to the spindle.
The traveler does not have a drive of its own but is dragged along behind the spindle.
High contact pressure (up to 35 cN/mm²) is generated between the ring and the traveler during winding, mainly due to centrifugal forces. The pressure induces strong frictional forces which in turn lead to significant generation of heat. This is the main problem. The low mass of the traveler does not permit dissipation of the generated heat in the short time available. As result, the operating speed of the traveler is limited.
Traveler Classification
Travelers are required to wind up yarns of very different types:
1. Coarse/fine;
2. Smooth/hairy;
3. Compact/voluminous;
4. Strong/weak;
5. Natural fiber/man made fibers.
These widely varying yarn types can not all be spun using just one traveler type is needed. Differences are found in: form, mass, raw material, finishing treatments of the material, wire profile, size of the yarn clearance opening for the thread.
The Form Of Traveller
The traveler must be shaped to correspond exactly with the ring in the contact surface, with the greatest possible surface area, is created between these two elements. The bow should be as flat as possible, in order to keep the center of gravity low and improve smoothness of running. These two features have a significant influence on the achievable traveler speed.


The flat bow must still leave adequate space for passage of the yarn. If the yarn clearance opening is too small, rubbing of the yarn on the ring leads to roughening of the yarn, a high level of fiber loss as fly, deterioration of yarn quality and formation of melt spots in spinning of synthetic fiber yarns

The Wire Profile Of The Traveller
Wire profile also influences both the behavior of traveler and certain yarn characteristics,
- Contact surface of the ring,
- Smooth running,
- Thermal transfer,
- Yarn clearance opening,
- Roughening effect,
- Hairiness.

In the figure wire profiles and average yarn clearance as a function of the traveler wire cross sections are given.
The Material Of The Traveller
The traveller should be:
1. Generate as little heat as possible.
2. Quickly distribute the generated heat from the area where it develops
over the whole volume of the traveller.
3. Transfer heat rapidly to the ring and the air.
4. Be elastic, so that the traveller will not break as it is pushed on the rings.
5. Exhibits high wear resistance.
6. Be somewhat less hard than the ring, because the traveller must wear away in use in preference to the ring.
In view of these requirements, travelers used in short staple spinning mill are almost exclusively made of steel. However, pure steel does not optimally fulfill the first three requirements. Accordingly, traveller manufacturers have made efforts over several decades to improve running properties by surface treatment. Suitable processes for this
purpose are:
*Electroplating, in which the traveller receives a coating of one or more metallic layers, (nickel and silver)
*Chemical treatment of the surface to reduce friction and pitting.
The Traveller Mass
The traveller mass determines the magnitude of frictional forces between the traveller and the ring, and these in turn determine the winding and the balloon tension. If the traveller is too small, the balloon will be too big and the cop too soft; material take-up in the cop will be low. An unduly high traveller mass leads to high yarn tension and many end breaks.
Accordingly, the mass of the traveller must be matched exactly to both yarn and the spindle speed. If a choice is available between two traveller weights, then the heavier is normally selected, since it will give greater cop weight, smoother running of the traveller and between transfer of heat out of the traveller.

The Traveller Clearer
Yarn consist of fibers that are bound into structure more or less effectively, but that are in any event relatively short. The yarn runs through the traveller, some fibers will be detached. For the most part they float away into the atmosphere, but some remain caught on the traveller. These retained fibers can accumulate until they form a tuft, and the resulting increase in traveller mass can lead to much increased yarn tension which finally can induce an end break.
Traveller clearers are mounted close to the ring in order to prevent formation of such fiber accumulations. They should be set as close as possible to the traveller without interfering with its movements. Exact setting is vitally important.

THE MACHINE DRIVE
About 20 % of production costs in spinning mill (tex 20) fall under the heading energy and of these costs about two thirds are used in the ring spinning section.
In a ring spinning mill with 25000 spindles and an operating time of 7000 hours per year, a saving of 10% on an annual power bill of 1 million dollars will bring very interesting financial returns.
Power supplied to the ring spinning machine is absorbed by:

- the spindle (including the travelers)	65 – 70%
- the drafting arrangements	25%
- the ring rail	5 – 10%

The Structure of The Cop
The cop is the characteristic form of package by the ring spinning machine. It has three clearly  distinguishable parts.
The lower curved base (A), the middle, cylindrical part (Z) and the conical part (S).
The Winding Process
If the point of lay of the yarn on the tube is constantly moved upwards, a cop structure could be occurred. There are two ways of achieving this; a gradual rise of the ring rail can be joint on the continual up and down movement or the spindle rail can be gradually lowered.
Ring frames produced today are exclusively of the moving rail type. The ring rail has to perform two movement in order to lay one main and one cross winding, gradual raising in small steps after each layer movement in order to fill the cop.

The Builder Motion
Owing to the rotation of the eccentric, the lever and the chain drum are continually raised and lowered. This movement is transferred to the ring rail by way of the discs (a and b) together with the chain and belt, thus giving the traverse movement.
Each time the lever moves down, it presses the catch to release the ratchet wheel (A), which a slight rotation of the drum (T) connected to the ratchet wheel.
A short length of chain (K) is thus wound up on the drum. This leads to rotation of the disc (a), shaft (W) and disc (b), and finally to a slight rise in position of the ring rail (R). The shaft (W) also carries a third disc (c) from which the balloon control rings (B) and lappets (F) are suspended by belts.
These are correspondingly raised and lowered but since disc (c) is slightly smaller than disc (b), the stroke length is somewhat shorter.

Building The Base
Raising and lowering of the ring rail (R) comes about because the eccentric (E) moves the lever (H) up and down and thus the disc (a) is continually turned alternately to the left and the right. Disc (a) carries the cam (N), which projects beyond the periphery the disc and thus forms a lobe of larger diameter than the rest of the disc.

At the start of winding of a cop, disc (a) is located in the position, in which the lobe noticeably deflects the chain (K). The effect of this deflection is that the chain elongation upon raising of the level (H) is not wholly transferred to the ring rail. Some part is lost as deflection at N. The traverse stroke of the ring rail no longer corresponds to the setting. It is shorter. Since the length of yarn delivered during each traverse stroke is the same, the volume per layer is increased thereby generating the curvature.

Disc (a) turns to the right in the same small steps and the cam is carried out of line with the chain. Finally the complete elongation of the chain is passed on to the ring rail and the cop takes up its normal build.