RINGS And TRAVELLERS - 3
- When the ring diameter is less, balloon diameter will be small. This leads to more yarn tension. Hence use lighter travellers.
- When the ring diamter is bigger, balloon diamter will be more. This leads to less yarn tension and the balloon touches the separator. Hence use heavier travellers
- When the tube length is short, the yarn tension will be more. Hence use lighter travellers
- When the tube length is long, the yarn tension will be less, hence use heavier travellers
- When the yarn contact area and ring contact area in traveller is closer, fibre lubrication is better especially in cotton. For this use heavier travellers
- When spindle speed is increased use lighter traveller with low bow height. At higher speeds, lighter travellers give lesser yarn tension. When low bow height travellers are used centre of gravity will be closest to the ring which aids in running of traveller.
- Use lighter travellers on new rings. This is done to reduce end breakages by reducing the yarn tension.
- Use heavier travellers on old rings. This is done to avoid bigger balloons
- Heavier travellers reduce hairiness
- When using lighter travellers, yarn stretch will be less. It helps for better yarn elongation
- During running-in the endbreakage rate should be kept minimum, hence use lighter travellers.
- The shorter the balloon, the lighter the traveller to be used, the higher traveller speeds can be achieved.
- The ring traveller, together with the yarn as a pull element, is set into motion on the ring by the rotation of the spindle. If the direction of pull deviates too much from the running direction of the traveller (spinning angle less than 30 degrees) the tension load will be too high.
Preconditions for good operating results
The maximum ability of the ring/traveller system to withstand occuring stress situation during operation determines the performance limit of the ring spinning and twisting machine. Traveller wear does not only depend on traveller material; problems of heat dissipation are of crucial importance, too. The heat generated between ring and traveller must be reduced as quickly as possible to avoid local temperature in the traveller wear zones. The ability of the traveller to resist to stress is determined by several factors. Investigations regarding improvements of rings and travellers aimed at a further increase of performance should above all make sure that all other conditions with a certain influence on the spinning process are optimal.
Therefore make sure that:
¥ the rings are correctly centered with regard to the spindles
¥ the yarn guide eyelet is well centered with regard to the spindle
¥ the spindle bearing is in good condition, thus preventing spindle vibrations
¥ the ratio between bobbin diameter and ring diameter is correct
¥ the concentricity of the ballon control ring with regard to the
spindle is correct
¥ the fibre tufts which accumulate on flange travellers are removed by
means of suitable traveller cleaners
¥ the climatic conditions (temperature and relative air humidity) are favourable
for the spinning process
¥ the air in the mill is free from disturbing particles that influence efficient
performance of the traveller
It has to be stressed that a smooth and well run-in track is of most importance.
Concentricity of spindle, ring, yarn guide and balloon control ring
Especially at high spindle speeds concentric positioning of ring, spindle, yarn eyelet and balloon control ring is required for keeping the ends down rate at low level. Spindles and rings must be aligned and centered absolutely parallel. Ring rails or ring holders should, therefore, be installed absolutely horizontally compared to the vertically fitted spindles. Ring and traveller form the main elements in ring spinning and twisting. They determine to a large extent performance and operating conditions of the machine.
The traveller accomplishes two main tasks while running on the ring at high speeds:
a) It gives the roving supplied by the feed rollers the necessary twist.
b) It assists in winding the yarn onto the bobbin in the form of a cop with ã correct tension.
During this operation the ring guides the traveller, which is essential for the perfect positioning of the yarn and the formation of the cop. The traveller is pressed against the ring track by centrifugal forces. The resulting frictional forces reduce traveller speed, which is dragged along by the passing-through yarn, and provide the yarn with the tensile forces necessary for assembling the individual fibres into the spun yarn as well as for limiting the yarn balloon.
Steel travellers are hardened to a certain degree and polished to a mirror finish. They can be adapted in shape, weight and surface finish to the ring, yarn type and yarn count. Nylon travellers of standard quality (for HZ and J rings) are made of highly wear-resistant polyamide. Extremely aggressive yarns are processed with glass-fibre-reinforced a Super Nylon travellers. Twisting and winding carried out by the traveller must be performed with appropriate yarn tension. The ratio between spindle speed and the speed at which the yarn is supplied determines yarn twist. Any change of this ratio is easily compensated by the traveller without having an influence on twisting, winding and tensioning.
On flange rings, the gliding speed of travellers having a suitable shape can be as rapid as 130 ft/s (88 MPH) or 40 m/s (140 km/h); on DIA-DUR coated rings the speed can to some extent reach 147 ft/s (100 MPH) or 45 m/s (160 km/h) . Having an average life span of 200-300 operating hours the traveller covers a distance of more than 18.000 miles (30.000 km) - a tremendous task for a small part of wire weighing only a few milligrams. These standards can even be surpassed by nylon travellers used on HZ rings, if operating conditions are favourable.
These high traveller speeds involve pressures of up to 35 N/mm 2 . But even if high-quality materials with an optimum of hardness and resistance to wear are used, these standards can only be reached if
¥ in the case of flange rings, a film of lubricating fibres is produced continuously,
¥ in the case of HZ and J rings, a sufficient amount of lubricant is consistently
d 1 = spinning ring diameter
d 2 = fitting diameter
h 1 = ring height
h 2 = ring height above ring rail
b = flange width
flange 1 = 3.2 mm
flange 2 = 4.1 mm
Spindles operating without vibrations contribute a great deal to a smooth operation of the traveller. Non-concentric spindles and spindles not running smoothly cause constant changes in yarn tension , because the traveller cannot run around the ring without being shaken.
Vibration-free movements of ring rail and ring holder
The ring rail should move smoothly without jerking. Vibrations and hard jolts at the reversing points of the ring rail disturb the operation of the traveller. Repeated changes in yarn tension cause the traveller to flutter. This results in increasing yarn breaks and in accelerated wear of ring and traveller.
Correct ratio between bobbin diameter, bobbin length, ring diameter and spindle gauge
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