Ringframe

Objective of Ring Frame 

Working of Ring Frame

Modern Developments in Ring Spinning Machine

1. Developments in Ring Frame

The ring frame has under significant changes. One of the most innovative developments that have been incorporated on this machine is compact spinning. The authors have discussed in detail different methods of spinning compact yarn in the paper titled ‘Different technologies to spin compact yarn’. The other significant modern developments will be discussed in subsequent section.

2. Changes in Spinning Geometry and Drafting Components Zinser Optimised Spinning Geometry

Zinser has claimed that the yarn path has been made short, thus causes less disturbance to twist transmission as compared with a long thread run. The programme controlled motor gives drive to yarn guiding element consequently bobbin build can also be pre-programmed from the control panel by setting winding length, traverse length and ring rail upward displacement. The traversing yarn guide remains at standstill at the start of the bobbin build operation for effective adaptation to the spinning tension that results into constant yarn tension.

3. Suessen ACP Cradle and Top Roller Loading via, Spring Plate

Suessen Active Cradle with special Pinspacer (ACP) is able to improve the yarn quality. The sector length of 15 or 20 mm, in the drafting system, where the inter-fibre friction is minimum, do not able to guide short fibres. The Pinsapcer of ACP deflects the fibre in this zone thereby increases the friction field of the front roller nipping line towards the cradle. The tendency of the fibre spread is suppressed along with improvement in fibre orientation and extension consequently improves overall regularity and strength of the yarn. The top rollers are also loaded directly by plate springs. The force of the springs is carried over to the top rollers without the use of any moving part and therefore involves no friction. The pre-tension of the spring can be changed by a cam at the front weighting unit to adjust the load.

4. Toyota Servo Motor-Driven Positive Lifting Mechanism

Toyota’s proprietary screw shaft positive lifting mechanism is used to on RX240 NEW ring for ring rail lifting motion. This eliminates disparity in the ring rail motion during long periods of continuous operation. The different cop parameters like chase length, cop diameter, winding start position, bobbin diameter (bottom and top), total lift, etc, can be fed via, key operation of the machine panel.

5. Zinser Synchro Drive, Synchro Draft and Servo Draft

Zinser Sychro Drive is a multi-motor tangential belt drive system. The system employed several motors arranged at defined positions to drive spindles through the tangential belt. The consistency in spindles speed relative to each other minimizes the twist variation apart from reduction in noise level and minimum power requirement. SynchroDraft transmission is for long machines to drive the middle bottom rollers from both ends, consequently minimizes twist variation between gear end and off end of the machine. Zinser ServoDraft system employs individual motors for driving bottom rollers of the drafting system. Hence yarn count and twist change can be done by simply feeding required parameters at the control panel of the machine that adjust the motors speed accordingly.

6. Toyota ElectroDraft System

The Toyota ElectroDraftSystem (optional) features independent servo motors drive for front and back rollers. The spindles are also driven by separate tangential drive system where one motor drives 96 spindles. Thus the required draft and yarn twist can be set via, control panel.

7. Multi-Motor Drive System Rieter FLEXIdraft

FLEXIdraft flexible drive, equipped on Rieter G 33 ring spinning machine, features separate drives for the drafting system and the spindles. This system enables change in the yarn count, twist and twist direction (S/Z) via, the control panel of the machine. The drafting rollers are split in the centre of the machine to ensure smooth running of drafting operation. On the basis of FLEXIdraft, each drafting system drive can be started or stopped individually via, FLEXIstart system . Thus depending on machine length, 1-sided or 2-sided drafting system drives are used. FLEXIdraft has a further advantage of noise level reduction due to elimination gear wheels.

8. Zinser Two-Fold Ply Yarn and Core Spun Yarn

Zinser offers to spin two ply twisted yarn (SiroSpun option) at the ring spinning machine . In SiroSpun process, two rovings are fed in parallel through the drafting system and are only combined after the front rollers nip point. Similarly hard and soft core-spun yarn (hard: Non-elastic, but high-tensile component in core and soft: Elastic component in core) can also be spun with CoreSpun system on Zinser ring spinning machines. The core-spun yarn can be spun with the little modifications and additional elements in the creel and drafting system of ring frame. Similarly, Multicount, Multitwist and other fancy yarn can be spun via, a software tool named FancyDesigner through Fancy Draft. The Fancy Designer generates the production data for ring spinning machine directly from the design. The Zinser memory card can transfer the design data from one machine to another.

9. Marzoli Fancy and Slub Yarn

Multi-motors drive system of Marzoli ring frame enables to spin fancy yarn like, slub, multi-twist or multicount, etc. The yarn contains controlled irregularities in term of thickness and twist variation can be actuated by moving bottom rollers at different speed via, a microcontroller. Marzoli MPN ring frame is also capable to process core spun yarn.

10. Suessen Two Ply and Core Spun Yarn

Suessen incorporates devices under different trade names to spin two ply and core-spun yarn on compact ring frame. The EliTwist® spinning method combines compact spinning and twisting of a yarn to get two-ply compact ring spun yarn. The EliCore® is the trade name given to spin core-spun on compact ring frame. EliCore®-rigid is for core-spun yarn with low elastic elongation but high strength filament in core whereas EliCore®-elastic is for high elongation and stand strength filament in core. EliCoreTwist® is trade name given to spin two-ply (SIRO) compact ring spun yarn. SUESSEN has redesigned the core-spun yarn (EliCore® and EliCoreTwist®) under the trade name COREflex®. This attachment works irrespective of the type of top weighting arm used and gives jerk- free movement to the traverse motion of fibre strand and filament. The filament feed roller is independently adjustable in two planes without touching the front top roller. Setting of tension draft and traverse motion is made at a central control panel.

11. Marzoli Twin Traverse Method

A double traverse motion for the roving guide used by Marzoli covers the wider area over the cots and consequently increases the cots and apron life.

12. Marzoli Wondercleaner for Cleaning Underwind

Marzoli rather uses a wonder cleaner to remove the underwind. Wondercleaner is an overhead cleaner with suction unit. This removes underwind only when the ring rail has reached certain minimum height.

13. Tackling Spindle Underwindings Rieter SERVOgrip

The yarn has to wind several times around the lower end of the spindle to hold it in the spinning position at the time of doffing. These underwindings often cause multiples end down and lead to fibre fly when machine is restarted after doffing. SERVO grip is a system of doffing ring cop without the underwinding threads. The main element of the SERVOgrip is a patented clamping crown. At time of doffing the ring rail moved downward and the clamping crown gets open while the spindle is still revolving slowly. The yarn gets inserted in the open crown and the crown gets closed afterward. When the cop is replaced, the length of the yarn remains firmly clamped, enabling piecing after machine is started.

Calculations of Ring Frame

Winding at Ring Frame

Drafting at Ring Frame

Causes of End Breakages

As stated above, there are many reasons of end breakages in the ring spinning. There are followings reasons of end breakages in ring frame:

  • Due to low TPI
  • Excess tension in creel
  • Creel jam
  • Improper spacer size used in drafting system
  • Faulty traverse mechanism
  • Damaged apron
  • Damages bottom roll
  • Damages front cots
  • Damages lappet hook
  • Burning of ring traveller
  • Ring gauge
  • Lappet and spindle gauge
  • Improper ring traveller used for particular count

Traverse guide or roving guider:

  •     Traverse guide when collecting fly blocks the regular passage of the roving.
  •     No middle traverse guide when using double roving.

Roving:

  •    Bad piecing in the roving.
  •   Stretched roving.
  •    Irregular roving.
  •    More twist applied in the roving leading to “shedding through” at the ring.
  •  Single roving when using double.
  •  Neps or slubs in the roving.
  •    More waste in the roving.

Drafting zone:

  •      Incorrect break draft.
  •      Roller lapping.
  •      Worn or grooved roller.
  •      Rust on the bobbin drafting.
  •      Worn aprons.
  •      Pneumatic system does not work properly so that the drafted strand of fibres fly entangles with the side end and cause breakage.
  •      Irregular distribution of draft in the drafting zones.
  •      Incorrect weight distribution on the top roller.
  •     Improper weighting of the top roller.
  •      Incorrect setting of the drafting rollers in relation to the average staple length of fibres under processing.

Lappet rail:

  • Incorrect setting of the lappet is not at the straight line with the top of the spindle.
  •    Dwell at each end of the traverse of the lappet rail.
  •   Starting up of the m/c when the lappet rail is at the top position.

Ring:

  •     Worn ring.
  •   Grease or gum on and under side of the ring flange.

Traveller:

  •    Heavy or lighter traveller than that required for the count.
  •    Worn traveller.
  •      Traveller flying off.
  •  No traveller clear creating tufts of fibre on the traveller.

Spindle:

  •     Lack of lubrication in the bolster cage or insert.
  •     Bent spindle is out of centre of the spindle.
  •    Excessive spindle speed than that requires for the count.
  •    Obstructed spindle speed by accumulation of fibres beneath the spindle.

Bobbin:

  •    Too larger or smaller diameter of bobbin than that suitable for the count.
  •    Jumbling bobbin.
  •      Vibrating bobbin.
  •   Badly worn bobbin in which yarn tends to catch at the starting up.
  •     Excessive full bobbin which rub against the ring.

Tapes:

  •      Bad joining of tapes causing spindle vibration.
  •     Tap ends flying off due to badly sewing.
  •       Slipping tapes.

Twist:

  •    Use of higher or lower twist multipliers than that requires for the count.

Other causes:

  •   Flying fibres.
  •   Incorrect relative humidities.
  •   Wind in the spinning section.
  •    Bad piecing up of the yarns.
  •    Shorter staple when used for higher count.
  •     Immature short or broken fibres in the sliver.
  •     Weaker fibres.
  •     Improper lubrication of the m/c.
  •     Lack of proper cleaning of the m/c floor.
  •    Irregular maintenance and over haul.

Principles of Drafting, Twisting & Cop Building in Ring Spinning

1. Introduction

The ring spinning is the final operation in the formation of the ring spun yarn. The basic purpose of the ring spinning frame is to attenuate the roving until the required fineness of the sliver is achieved. The ring spinning machine was first invented in 1828 in America. The initial and maintenance cost of the ring spinning is quite high.The ring frame contributes about 60% towards the final cost of production of the yarn. So every effort is being put in to make modify the ring spinning machine to give more productivity at a less cost.

2. Functions of Ring Spinning Frame

1. Drafting

The basic function of ring spinning frame is drafting.Drafting is carried out such an extent so as to achieve desired fineness of the yarn. The drafting is carried out by using 3 over 3 roller drafting arrangement with double apron support. At the ring frame a draft of 15 to 40 is given (Some times also up to 50).

2. Twisting

The attenuated yarn formed by drafting is weak and lack cohesion.In order to give strength to the final yarn, twist is inserted. Twist is inserted at the ring frame by using the popular traveler method. The amount of twist inserted in the yarn varies with the count of the yarn. To ake finer yarns, greater TPI is given and vice versa. The value of twist multiplier (TM) at ring frame generally ranges from 3 to 5.

3. Winding

The final yarn produced after drafting and twisting is wound on special ring bobbins also called as cops. The built of the package kept is such which is suitable for storage, transportation and further processing.  

3. Various Components of Ring Frame

A typical ring frame is divided in to four zones:

  1. Creel Zone
  2. Drafting Zone
  3. Twisting Zone
  4. Package Winding Zone

We shall discuss the above components of the ring frames:

1. Creel Zone

It is simple device that holds the roving. It is important that roving should unwind properly and evenly to avoid any false drafts or roving breakages. Roving bobbins are held vertically by inserting roving bobbin on the bobbin holder placed at the upper portion of the frame. Upper part of bobbin holder is suspended by a bearing. The roving bobbin is pushed upward on to the bobbin holder. As the roving is pulled forward by the drafting rollers,the roving bobbin rotates and unwinding takes place. Brake arms are used to avoid excessive rotation.

2. Drafting Zone
  • Since the at the ring frame greatest value of draft is given,the drafting zone of ring frame is the most important part of the machine that directly influence the evenness and strength of the yarn. So it is important to have a precision control on the fibres in the strand which is being drafted out to suppress the drafting waves.
  • The fibre strand in the main drafting field consists of only few remaining fibres. There is hardly any friction field and fibre guidance provided by the rollers alone is inadequate. Special fibre guiding devices are there fibre needed to carry out a satisfactory drafting operation double apron drafting arrangement with longer bottom aprons is the most widely used in modern ring frame.
  • In double apron drafting system two revolving aprons driven by the middle rollers from 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 with short ones that they can be easily replaced in the event of damage and there is less danger of choking with fluff.
  • The drafting unit system is capable of working fibres of up to 60 mm(carded and combed cotton, blends and chemical fibres) with draw values of between 10 and 80.
  • The roving is first subject to a break draft with values of between 1.5 and 2 and successively a main draft in the apron area until the desired count is achieved.The spinning counts are between Ne 5 and Ne 150 (118.4 Tex).

Apron: Rubber apron is made of synthetic rubber material, with excellent wear-resistance/oil-resistance/ageing resistance and smooth surface. In addition, it is good stability, flexibility & wide application. It is used in drafting system of ring frame and some other modern drafting system in spinning machine. It contains cradle for guiding its direction of length.

Rubber cot: It is one type of synthetic rubber material which is used in top rollers of ring frame drafting system. The rubber cots also used on drawing frames,combing machines. Its hardness can be varied. The hardness of rubber cots is expressed by degree. Generally harder cots are used in back roller and softer cots are used in front roller. Hardness ranges are given below:
Soft: 60° to 70° shore
Medium: 70°  to 90°  shore
Hard: Above 90°  shore
80°  to 85°  shore are mostly used at the back roller and 63 to 65 shore at front roller.

Using Trumpet or traverse or condenser Guides: The strand of roving has few numbers of fibres in a cross-section and upon drafting even fewer number of fibres will remain in a yarn. These fibres have hardly any cohesion between themselves. Special fibre ding elements are therefore essential to carry out drafting without breaking the strand. For this purpose specially designed trumpet guides are used in drafting zone to help keep the fibre mass together and to avoid tearing apart of the strand. Three trumpet guides or condensers are used one just before the back pair of rollers.

Types of drafting system:

a) Spring loaded drafting system or pendulum arm (Ex-SKF PK 2025 or Texparts 2035)

  • Loaded by spring
  • Applied pressure in all drafting zone is not uniform
  • Conventional system

b) Pneumatic drafting system: SKF PK 3025

  • Loaded by pneumatic pressure i.e. compressed air
  • Uniform pressure is applied to all drafting rollers
  • Consistent yarn quality is achieved
  • Modern drafting system
3. Twisting Zone

In the twisting zone following elements help to impart twist in the yarn-

  • Lappet hook or thread guide
  • Ring
  • Traveller
1. Lappet hook or Thread guide

It is yarn guide made by bending a wire named snail wire.Snail wire may be different in types like p-shaped wire.

Functions:

  • Its main function is to guide the yarn thus maintain the security of the yarn.
  • It prevents yarn collision with adjacent yarns.
  • It surface should be smooth to prevent rubbing of yarn.Rubbing creates yarn hairiness.
2. Ring

There are some important functions of ring.These are given below:-

  • Ring guides the circular run of the traveller.
  • It also helps in twisting by means of running of the traveller
  • It also acts as a track of traveller.

Classification of ring:
A)According to origin or element:

  1. Metallic ring
  2. Ceramic ring

B)According to number of flange:

  1. Single flange ring
  2. Double flang ring

Flange:The path of traveller on the ring is called flange .It may be single or double.

Flange width: The term flange width express the difference the outer diameter and inner diameter of a ring. Flange width is express the diffrence the outer diameter and inner diameter of a ring.Flange is expressed in flange number.     
                                    
Flange width = (Flange no.+3)/32 inch
Relationship between ring dia and bobbin dia: 
                                                                               B=0.39R
Where, B=Bear bobbin dia and  R=Ring dia

3. Traveller

Traveller is the most tinny and simple mechanical element in ring frame which carries the most important function like simultaneous twisting ,winding ,thread guide etc.

Function of traveller: Traveller is important in ring frame as given below-

  • Twisting on drafted strand of fibre.
  • Winding of yarn on the bobbin.
  • Maintain winding tension of the yarn by the frictional resistance between the ring and traveller.
  • It acts as a guide for yarn yarn on the way to be wound on the bobbin.

Traveller Speed and its Effects: Traveller does not have a drive of its own. It drags behind the spindle Since the spindle rotates at a high speed, a high contact pressure is generated between the ring and during winding, mainly due to centrifugal force. The pressure introduces strong frictional forces which in turn lead to significant generation of heat.

Part of Traveller: There are three parts as given below ;

  • Bow
  • Horn
  • Flange

Type of Traveller: Traveller can be classified in to following two ways:
1) According to shape:

  • C-traveller
  • Elliptical traveller

2) According to the X-section of wire:

  • Round traveller
  • Flat traveller
  • Semi-circular traveller

Specification of traveller: A ring traveller is specified by the followings:

  • Traveller no.: 1,2,3,1/0,2/0,3/0 etc.
  • Cross section of the wire and shape
  • Flange no.
  • Surface finish-carbon finish,nickle finish etc.
  • Type of materials etc.

Notation of traveller: A traveller can be notified as follows:
3/0 MS/HF,5/0 MS/FF,7/0 HI-NI/HF
Here,
3/0-Traveller number
MS-Mild steel
HF-Half flange
FF-Full flange
HI-NI-High Nickel finish

Traveller no. or size of traveller: If the weight of 10 traveller is 10 grains then number of those traveller is 1 and so on. Recommended traveller no. for various yarn counts:

Count(Ne)Traveller No.
162
201-2/0
303/0-4/0
406/0-8/0
5010/0-12/0
6013/0-15/0
8016/0-19/0
10019/0-20/0

Force Acting on Traveller:

  1. Traveller weight
  2. Frictional force between ring and traveller
  3. Centrifugal force
  4. Balloon tension
  5. Winding tension

Limitations of the Traveller/Ring Arrangement:
Speed: There is limitations faced by the ring frame is its incapability to further increase its productivity and speed. This is mainly due to use of ring arrangement. At high speeds the traveller generates significance amount of heat due to friction with the ring. If the speed of ring frame is to further increase, owing to a very small mass and size of the traveller and ultimately entire machine is limited. Currently the the spindle of the ring frame is capable of running up to 30000 rpm(Practical speed) and the use of traveller permits the speed only to be raised up to around 22000 rpm.Another way of increasing the speed of ring frame is by using ring with smaller diameter so that spindle speed can be further increased without increasing the frictional forces on the traveller/ring. This can decrease the productivity of the machine. However this problem can be rectified by using automatic doffing devices.

4. Package Winding Zone

The yarn wound on the entire length of the package after twisted by the traveller called as cop.

  • In order for the winding to take place there should be a difference in the surface speed between the spindle and the traveller.
  • The traveller has no drive of its own instead it is carried along with the yarn which is being wound on the cop after passing through the traveller.
  • The frictional forces between the spindle and the traveller and also the air drag because of the ballon formation between lappet guide and the spindle makes the surface speed of the traveller less than that of the spindle.
  • This automatically fullfills the requirement of winding. The traveller and the spindle cooperate with each other to perform winding.
  • In order for the yarn to be properly wound on the entire length of the cylindrical ring bobbin(cop),the ring is raised and lowered which is mounted on a longitudinal ring rail.

Spindle:The spindle is the main part of a ring frame which helps in twisting,winding simultaneously.Sometimes spindle referred as heart of spinning.It hold the bobbin,somewhat loosely but tight enough to prevent slippage.

Functions of spindle:

  1. Twisting and winding is performed by spindle.
  2. It holds the bobbin.
  3. The capacity of ring frame is mainly determine by the number of spindle.

Different parts of spindle: The parts of the spindles are given below:-

  • Spindle blade
  • Wharve
  • Bolster
  • Lock
  • Bearing
  • Bolster cage

4. Package Built of Ring spinning frame

A typical form of a package produced by a ring spinning frame is called as the cop. The package is produced on a tube of paper, card board or plastic material. About 10 mm of the tube is left free of the yarn on both upper and lower ends. The tube has slight taper corresponding to the taper of the spindle so that the package can be firmly secured on the spindle.

The structure of the cop is divided in to three distinct parts:

  1. The upper conical tip
  2. The middle cylindrical parts
  3. The lower curved base

The cop has two distinct layers of the yarn wound on its surface i.e. the main surface layers and the cross winding layers. The main winding layers are close to each other and are densely wound whereas the cross winding layers are openly laid and are loosely wound. The cross winding layers separates the main winding layers so that the high tension of the yarn may not cause the successive layers to be pressed causing problems in unwinding. The package built of the cop as compared to that of the roving bobbin is much more complex which also requires complex mechanical arrangements; however it is optimal for unwinding at a very high speed on the winding machines.

5. The Builder Motion

To obtain the above mentioned built of the cop, complex mechanical arrangement called as the builder motion is provided at the ring frame. The builder motion achieves the structure of the cop by performing the following tasks:

1)The ring rail on which the ring is mounted is moved up down by the builder motion in a special manner. The ring rail while moving up is moved slowly but with an increasing speed and is moved down quite faster but with a decreasing speed. During the slow upward movement of the ring rail, a dense main winding layer is laid and during the fast downward movement, a loose cross winding to be 2:1. This difference in yarn length in the upper and middle part creates a taper or conical shape of the upper parts. The stroke or the distance by which the ring rail moves up and down is less than the total winding height(lift) of the tube.

2)The stroke of the ring rail is deliberately kept less than package tube height so that the ring rail can be moved upward by a small distance from the previous point of lay of the yarn after one complete layer of the yarn has been laid. The helps in creating the lower curved base of the package. In older machines ,instead of moving the point of lay of the ring rail upwards after every layers has been laid, the spindle i made to move downward. This is carried out by mounting the spindles and spindle rail. However in the modern machinery this arrangement is no longer used and only the ring rail is made to move up and down and also its point of lay is continuously lifted upwards by a small amount.This somehow reduces the complexity of the builder motion. “The task of builder motion to move the ring rail up and down is carried out by using special heart shaped eccentrics or cams in its drive given to the ring rail. These eccentrics in its rotary motion give an up and down motion to the ring rail. The rise in point of lay of the ring originates by using a ratchet wheel that after every layers of the yarn makes the point of the lay of the ring rail to shift upwards”.

There is warve to run the spindles of ring frame,warve is started through tape and 1 tape is attached with 4 spindles of R/F. If spindle tape is loose then spindle speed will be slow and low tpi in the yarn will be generated.

6. Use of Balloon Control Rings (BCR)

To achieve greater production speeds with minimum friction produced by the traveller, the spindle and the rings used on the modern ring frames are comparatively small.This small ring size only permits a very limited length of yarn to be wound on the bobbin and the doffing would have to be perform more frequently and hence the productivity would suffer. On modern machines this problem has been overcome by using longer length of the spindles and bobbins so that even with less package diameter more yarn length can be wound. This reduce the amount of doffing and productivity can be increased in this way.

The use of long spindles will mean that the distance between the lappet guide and ring would be quite high resulting in a formation of a bigger balloon. The greater balloon size has following disadvantage:

To facilitate a larger balloon during winding, more spacing
i)will be required between the adjacent spindles and hence the size of the machine has to be increased.
ii)The large balloon causes the air drag on the yarn to increase and due to which the yarn can be broken due to balloon collapse.

In order to avoid these disadvantage effects,balloon control rings are used. Each balloon control rings divides the balloon in to two smaller sub balloon which are more stable and creates less air drag on the yarn. The use of balloon control rings is illustrated below:

The balloon control rings enable the spinning operation with long spindles at high speeds. However the use of such rings cause the surface of the yarn to become wough and abroaded as the yarn is rubbed against the surface of these rings. This can also creates more fly in the spinning department.

7. Use of Separator

Most of the end breakages during spinning occur because of the weak spots created by the spinning triangle. When the thread breaks the free broken end of the thread lashes around the spindle. If a protective plates called as separator are not provided to separates the adjacent spindles, the broken end of the thread can get entangled in to the neighboring spindles causing more threads to break. So a single end breakage can cause a chain reaction of the yarn breakages in all the spindles places in one time. To prevent this separator plates made up of aluminum or plastic is placed in between every adjacent spindle.

8. Principles of Operation of Ring Frame

  • The roving bobbins are creeled in appropriate holders. Guide rails lead the rovings in to the drafting arrangement which attenuates them to the final required count.
  • The drafting arrangement is inclined at an angle of about 45-60˚. It is one of the most important assemblies on the machine since it has considerable influence on irregularities present in the yarn.
  • After drafting the arrangement,the machine have twisting and winding zone.
  • Upon leaving the front rollers,the emerging fine fibre strand receives the twist needed to give it strength.The twist is generated by the spindle, which rotates at high speed. Each revolution of the spindle imparts one turn of twist to the fibre strand. Spinning of yarn is thus complete.
  • In order to wind up the twisted yarn to the bobbin mounted on spindle, a traveller is required cooperate with spindle. The traveller moves on guide provided on the ring encircling the spindle.
  • The traveller have no direct drive; instead, it is carried along by the yarn it is threaded with.The speed of the traveller is lower than that of the spindle owing to significant friction generated between the traveller and ring.
  • This difference in speed enables winding of yarn to bobbin.
  • Winding of yarn on to the bobbin is done by raising and lowering the ring rail. The traverse stroke of the ring rail is less than that of the bobbin height. The ring rail must therefore be raised by small amount after each layer of coils.

9. Cross Section of Ring Frame

The ring frames are two sided machines with the spinning positions located on the both sides of the machine. Each spindle is a spinning position. The spindle rail houses the spindles. The creel housing the feed roving bobbins are arranged in two rows on each side of the machine. The drafting arrangement is carried on the roller beams. Each intermediate section stands on the two feet adjustable in height by means of screws, thereby easy leveling of the machine. In modern machines, an auto-doffer is also provided. Including the auto-doffer, the width of the machine varies from 800 to 1000 mm. Today,the machine length can reach 50 m. Spindle gauges usually lie between 70 and 90 mm.

10. Yarn Realization

Yarn realisation is the term used to denote the percentage of yarn produced for given weight of raw cotton. It depends on the waste extraction.         
                                                 
Yarn realization% = (92-Z), for carded yarn                                                                                                =(95-Z)(1-C/100)-3 ,FOR COMBED YARN
Where, Z=trash extracted (%) in the process stages ,C= comber noil%

Factors Considered for Selection of a Traveller:

  • Yarn count: Higher the yarn count,lower will be the traveller weight.
  • Spindle speed: If the spindle speed is high,then the yarn tension will be high, so lighter traveller should be used to minimise the tension.
  • Ring dia: With increase of ring diameter yarn tension as well as frictional area increases. So lighter traveller should be used.
  • Empty bobbin dia: When empty bobbin dia increases, winding angle decreases resulting a higher yarn tension. So a light traveller should be used.
  • Lift of bobbin: If lift of bobbin increases,yarn tension increases, so less weight traveller should be used.
  • Cross section of  traveller: We know,if frictional area increases, lighter traveller should be used.

For flat-traveller weight decreases              
For semi circular-traveller weight increases              
For circular-traveller weight increases

NOTE:

  1. Usually used ring dia-33,36,38,40,42,45 mm
  2. Ring cop diameter: Empty bobbin dia= 2:1 or 2.5:1
  3. Bobbin length= 5*Ring Diameter
  4. Bobbin lift= Bobbin length-20 mm

Draft limits: Higher draft resulted reduction in yarn quality-

  • Carded yarn(Cotton): up to 35
  • Carded blended: up to 40
  • Combed cotton and blended yarns
  • Medium fineness: up to 40
  • Fine yarn: up to 45
  • Synthetic fibres: up to 45(-50)

11. Break Draft

Total draft in the ring frame is limited. Since the main draft should not exceed its limit, an additional draft is implied in the back zone (Between back and middle roller). This draft facilitates the main draft and known as break draft.
Normal twisted roving, total draft up to 40:
break draft should be 1.1-1.4
Strong twisted-1.3-1.5
When total draft exceeds 40,
break draft :1.4-2

12. Twist Insertion in Ring Frame

In ring spinning, twist is inserted in to the thin strand of fibres emerging from front roller nip to form the yarn. During the spinning, spindle is positively driven by belt or tape at a constant speed.The traveller is dragged around the ring by the yarn being wound on to the bobbin. The rotation of traveller allows the yarn between the traveller and pigtail guide to rotate at the same speed. It is the roating balloon that inserts the actual twist in to the yarn. As the twist is generated in the yarn balloon, it travels past the yarn guide towards the front roller nip. But the twist can not quite reach the nip line of the front rollers, because fibre emerging from the nip have to be diverted inwards to be twisted around each other. So a small triangle of fibres, without any twist is formed between the front roller nip and fibre convergence point  is known spinning triangle or twist triangle.

Twist(Turns/meter)=Spindle rpm(revolutions per min)/Yarn delivery speed(meters per min)                                   TPI=Ring traveller rpm/FRD                             
Ring traveller rpm=(Spidle speed)-(Wind on rpm)     
  TPI=TM*√Count(Ne),

  • TM for synthetic material is 2.7 to 3.2.
  • TM for carded material is 3.8 to 4.2.
  • TM for combed material is 3.6 to 4.00.

So, the TPI of combed yarn is kept less than carded yarn because combed yarn is more uniform than carded yarn due to reduction in the short fibres ,so strength is more in combed yarn.

Relationship between TF(twist factor) and Tm(Twist multiplier)–

  • For TPCM(Twist per centimeter)  ,T.F=9.56*Tm
  • For TPM(Twist per meter) ,  T.F.=956*Tm

13. Winding-On

The yarn balloon rotates at a slower speed than the spindle due to air drag (resistance) on yarn and friction between traveller and ring. The difference in rotational speeds of the balloon and the spindle (bobbin), allows the yarn to be wound up on to the bobbin.

Vwind-on = πdwind-on*(nbobbin-ntraveller)
Where,
Vwind-on = Windin on speed
πdwind-on = circumference of yarn package
ntraveller = rotational speed of traveller
nbobbin = bobbin rotation speed(constant)

14. Physics of Ring Spinning

Where, Tt=Yarn tension at traveller,         
Tw=yarn wind-on tension,
N=Normal force between ring and traveller, 
Fa=Air drag on traveller
F=Frictional drag between ring and traveller(=NμRT) , 
mg=traveller weight,
T=Centripetel forces on traveller = mRw
(where m=traveller mass ,R=ring radius ,w=spindle speed)

All these forces must be balanced during spinning. It is possible to drive equations for this force balance to show the effect of variables such as traveller weight, balloon size, yarn count etc. on the spinning tension.
In equilibrium:                                 
ϵ tangential forces=0,
ϵ radial forces=0,
ϵ vertical forces = 0
Ignoring F and mg,

this gives the yarn wind-on tension,                                                          
Tw=mw2R/(Cosα+Sinα*(Cosβ-Sinβ tanө )/μRT

Some implications of the equation:

  1. Wind-on tension increases with the square of spindle speed(w) i.e. increasing the spindle rotational speed will drastically increase the yarn tension,which may lead to increase ends-down.This limits the maximum spindle speed in ring spinning.If spindle speed is reduced to reduce yarn tension,the production rate will drop.
  2. Winding tension decreases as the package diameter decreases.This puts a limit on the minimum diameter of the empty bobbin.
  3. Since larger balloon means higher yarn tension,the winding tension increases as the balloon gets longer.This limits the length of bobbin.

Empty bobbin or tube diameter/ring diameter=0.47

4.   Winding tension increases as the radius (R) increases.This limits the size of the full package that must fit inside the ring.The package capacity is approximately proportional to ring diameter square, so a large ring diameter is desirable for increased package capacity.                                     
         
Max. spindle speed α 1/√Ring diameter                                                                         
and                                        
Max.Linear traveller speed α √Ring diameter

This is why we do not see ring spinning machines with very large rings and with very small bobbins(tubes). For coarser and stronger yarns,large ring radius and yarn packages are used to allow for more yarns on the package.For finer yarns,both ring radius and the package size are smaller.Most worsted yarns are spun using rings between 45 and 75 mm in diameter at spindle rotational speed between 7000 and 12000 rpm.Short staple yarns are spun with smaller rings,but a about twice the spindle speed used for worsted yarns.    
5.   Winding tension increases with traveller mass.Heavier yarns require a greater centripetal force to keep them rotating. Traveller mass is used as a variable to increase the tension and generate the higher centripetal force for heavier yarns. The traveller mass is usually chosen according to the linear density of the yarn being spun.    
6.    Winding tension increases with an increase in the frictional coefficient between the ring and the traveller (μRT).

15. Factors Affecting Size of Balloon

1. Count of Yarn

1)Fine count-Lower balloon size(Ring radius and package size are smaller)
2)Course count-Higher balloon size(use heavy ring traveller)

2. Winding and Unwinding Speed

1)Higher speed-higher balloon size
2)Lower speed-lower balloon size

3. Size and Shape of Package

Large package-higher balloon size

4. Position of Lappet Book

Greater distance-higher balloon size

5. Lift of the Package

Greater lift-Higher balloon size

16. Types of Waste

  1. Pneumafill waste-It is fan waste
  2. Roving waste
  3. Bonda waste-It is the waste during cleaning of cots,lapping etc.
  4. Hard waste-There are followings hard waste are:
  • Kirchi- It is like ribbon like form during winding and breakage occur at the time of unwinding due to single and double layer. This waste generated during to start-up and getting .We should avoid this.
  • Ring cut
  • Over spoiled
  • Bottom spoiled
  • Lapetta- It is due to over getting.
  • Floor cleaner waste.-Over bobbin.

Twisting at Ring Frame