Important elements of ring spinning and useful data.
The invention of Ring frame is credited to John Thorp in Rhode Island in 1828.Ring concentric with spindle by Thorpe and Traveller by Jenks in the second quarter of the 19th century laid the foundation of Ring Spinning. By the end of 19th century Ring Spinning was a fairly well perfected process, and therefore, the output of Ring Spindle was much higher than that of mule spindle. Consequently, the world textile industry made a major shift to Ring Spinning in the first quarter of the 20th century. The important elements of Ring Spinning and useful data are described in the following editorial by by Dr. H.R. Sheikh, Editor (Spinning).
The pneumatically loaded weighting arms for drafting systems were developed during 2000 to replace the coil spring loaded weighting arms. The newly developed weighting arms have many advantages.
The Weighting Arm Texparts(r) PK 3000 replaced PK 2000, is an innovative and completely pneumatic weighting arm system for short-staple ring spinning machines.
The Weighting Arm Texparts(r) PK 1660 series with a coil spring loaded system, is now replaced by PK 1661 with individual pneumatic loading of the top rollers for a worsted ring frames.
The development of pneumatic loading concept for weighting arms is a major advancement in drafting system technology. The pendulum pressure by pneumatic loading is kept at the same level as for coil spring loading as follows:
Front Middle Back
20 20 15 da N
20 15 20 da N
30 20 25 da N
1 Newton = 0.101279 KGM force,
1 daN = 10.01279 KGM force.
Shore hardness of cots and buffing
Shore Hardness of cots is of three types:
Soft = 600 to 700
Medium = 700 to 900
Hard = Above 900
The soft coverings produce greater area of contact, cover the strand effectively and guide the fibres more efficiently. The buffing of cots is usually done after 3000 hours of use and the material removed is 0.2 m.m. The total covering thickness should never be reduced below 3.5 mm.
Break draft is adjusted according to the twist imparted to roving and the total draft required as follows:
Normal twisted roving, break draft = 1.14 to 1.25
Strong twisted roving, break draft = 1.3 to 1.5 .
Where total draft exceeds 40, break draft = 1.4 to 2.0
Offset of front top roller
When the front top and bottom rollers are co-axial, spinning triangle will be long and therefore longer weak spot with more end-breakages.
However, the edge fibres will be twisted more effectively into yarn which will be smoother, less hairy with less fly. When front top roller is offset by a distance of 2 to 3 mm, with respect to the axis of bottom roller short spinning triangle in formed.
As the weak spot is smaller, consequently, end-breakages will be lower, but some edge fibres will escape twist and lost as fly. In this context, some edge fibres will have only one end incorporated into the yarn with the other end protruding out of the yarn surface leading to hairy yarn.
Ring and Traveller combination
The material of the Ring and Traveller, surface characteristics and form of the elements is important from the view point of wear resistance and smoothness of running.
The anti-wedge ring and elliptical traveller is preferred because it facilitates higher Traveller speeds as compared to conventional ring and c-shaped Traveller combination.
At high traveller speeds and high centrifugal forces material is abraded in the form of fibre particles. The fibre particles are partially ground to a paste of small, colour less, transparent and extremely thin platelet constituting a lubricating film around the ring on which Traveller moves. Consequently, Traveller wear is reduced and ensures smooth running for a longer period.
3. Spindle and Bolster
Spindles are generally made from Aluminum alloys, whereas the Bolsters are made from cast iron or steel. The fixed neck bearing is used at the Bolster top and flexible foot bearing at the spindle tip.
The chamber between the blade and the bolster is filled with lubricating oil, which is generally replaced after 10,000 hours. In order to prevent vibrations of the spindle damping spiral is provided below the spindle tip.
Spindle centering relative to the ring is most important. It should be as accurate as possible otherwise excessive Traveller wear and burn off will occur.
Spindle drives and spindle speed
The 4-spindle tape drive system is most common. The single and double tangential belt drives are also used which eliminate drive components under the machines. Spindle speed is the most import important machine element and mechanically the spindle can be rotated upto 28,000 RPM.
Separator plates of aluminum or plastic material are arranged between spindles to prevent lashing of broken ends.
Length of balloon
The length of balloon is controlled by synchronizing the movements of the ring rail and the lappet rail.
For longer lift machines, Balloon Control Rings are used and double balloon is created, which is stable even at lower yarn tension.
However, yarn rubs the control ring and roughening of the yarn takes place. In case of synthetic fibres there may be melt spots!
Textile Institute of Pakistan
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|Publication:||Pakistan Textile Journal|
|Date:||Feb 29, 2012|
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