Hi viewers , Be ready , because now I'm going to give a large post based on Ring Frame , seriously large ....
Actually , now my topic is not Ring Frame , but more important than Ring Frame ....
Its about drafting .....
Lets start.....
Drafting arrangement is the most important part of the Ring Frame. It keeps a Great importance on the evenness and strength of the yarn by influencing some special properties --
- Type of Draft
- Drafting design
- Setting of drafting arrangement
- Selection of drafting elements
- Amount of draft
Parameters of Drafting -
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o If higher drafts can be used with a drafting arrangement, then coarser roving can be used as a feeding material.This results in higher production rate at the roving frame and thus reducing the number roving machines required, space, personnel and so on.
o In fact increase in draft affects the yarn quality beyond certain limit. Within the limit some studies show that increase in draft improves yarn quality.
The following draft limits have been established for practical operation:
- Carded cotton- up to 35
- Carded blends - up to 40
- Combed cotton and blends(medium counts) - up to 40
- Combed cotton and blends(fine counts) - up to 45
- Synthetic fibers - up to 50
o The break draft must be adapted to the total draft in each case since the main draft should not exceed 25 to 30. It should be noted that higher the break draft, more critical is the break draft setting
o The front top roller is set slightly forward by a distance of 2 to 4mm relative to the front bottom roller, while the middle top roller is arranged a short distance of 2mm behind the middle bottom roller.
o Overhang of the front top roller gives smooth running of the top rollers and shortens the spinning triangle. This has a correspondigly favourable influence on the end break rate.
o Rubber cots with hardness less than 60 degrees shore are normally unsuitable because they can not recover from the deformation caused by the pressure on the top roller while running.
o Soft rubbercots for toprollers have a greater area of contact, enclose the fibre strand more completely and therefore provide better guidance for the fibres.However softer cots wear out significantly faster and tend to form more laps.
o Normally harder rubbercots are used for back top rollers, because the roving which enters the back roller is compact , little twisted and it does not require any additional guidance for better fibre control.
o In the front top roller, only few fibres remain in the strand and these exhibit a tendency to slide apart. Additional fibre guidance is therefore necessary.Therefore rubbercots with hardness levels of the order 80 degrees to 85 degrees shore are mostly used at the back roller and 63 degrees and 65 degrees at the front roller.
o If coarse yarns and synthetic yarns are being spun, harder rubbercots are used at the front roller because of increased wear and in the case of synthetic yarns to reduce lapups.
o Three kinds of top roller weighting(loading) are presently in use
- Spring loading
- Pneumatic loading
- magnetic weighting
o The fibre strand in the main drafting field consists of only a few remaining fibres. There is hardly any friction field and fibre guidance provided by the rollers alone is inadequate. Special fibre guiding devices are therefore needed to carry out a satisfactory drafting operation. Double apron drafting arrangements with longer bottom aprons is the most widely used guding system in all the modern ring frames.
o In doube apron drafting system two revolving aprons driven by the middle rollers form a fibre guiding assembly. In order to be able to guide the fibres, the upper apron must be pressed with controlled force against the lower apron. For this purpose, a controlled spacing (exit opening), precisely adapted to the fibre volume is needed between the two aprons at the delivery. This spacing is set by "spacer" or "distance clips".Long bottom aprons have the advantage in comparison wiht short ones, that they can be easily replaced in the event of damage and there is less danger of choking with fluff.
o Spindles and their drive have a great influence on power consumption and noise level in the machine The running characteristics of a spindle, especially imbalance and eccentricity relative to the ring flange, also affect yarn quality and of course the number of end breakage. Almost all yarn parameters are affected by poorly running spindles. Hence it should be ensured that the centering of the spindles relative to the rings is as accurate as possible. Since the ring and spindle form independent units and are able to shift relative to each other in operation, these two parts must be re-centered from time to time. Previously, this was done by shifting the spindle relative to the ring, but now it is usually carried out by adjusting the ring.
o In comparison with Tangential belt drive, the 4-spindle drive has the advantages of lower noise level and energy consumption, and tapes are easier to replace.
o Lappet guide performs the same sequence of movements as the ringrail, but with a shorter stroke, this movement of the guide ensures that differences in the balloon height caused by changes in the ring rail positions do not become too large. This helps to control the yarn tension variation with in control, so that ends down rate and yarn characteristics are under control.
o Spindles used today are relatively long. The spacing between the ring and the thread guide is correspondigly long, thus giving a high balloon.
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