Ring frame
Ring
spinning:
The
ring spinning is the most widely used form of spinning machines due to
significant advantages in comparison with the new spinning process. Ring spinning is a method of spinning fibres, such as cotton, flax or wool, to make a yarn. In
ring spinning, the roving is the first attenuated by using drawing rollers,
then spun and wound around a rotating spindle which in its turn is contained
within an independently rotating ring flyer. Traditionally ring frames could
only be used for the coarse counts, but they could be attended by semi-skilled
labour.
Objects
of ring spinning frame:
Following
are the core objects of ring spinning-
●To draft the roving fed to the ring frame.
●To impact the strength to the fibre strand by twisting.
●To wind up the resulting yarn on to bobbin.
●To build up the yarn on to bobbin in form of a suitable for storage,
transportation and processing.
Main
operations of ring machine:
●
Creeling: By this process the drawn sliver is introduced to the draft zone from
sliver can manually.
●
Drafting: To reduce the weight per unit length by drafting i.e, passes of
sliver through three or four pair of roller of different speed.
●
Twisting: To make turn within the fibre of the drafted material to hold them
together.
●
Winding: To wound the roving or to upright bobbin in a particular manner so
that it can be used in the next machine easily.
●
Building: By this process the roving is wound in full length of the bobbin in
such a form which will facilitate handling, transfer and feeding to ring frame.
●
Doffing: Doffing is to replace an empty bobbin at the place of fully wound
bobbin.
Features
of a good ring:
● The best quality raw material.
● Good but too high surface smoothness.
● An even surface.
● Exact roundness.
● Good running condition.
● Good, even surface hardness, higher than traveler.
● Good operating life time.
● Correct relationship between ring and bobbin tube diameter.
● Horizontal disposition.
● It should be exactly centered to the spindle.
What is ring spindle? | Essential qualities of a spindle | Inverter drive for spindle
Definition of Ring Spindle
Spindle is the heart of ring frame.
A spindle is regarded as a production unit of a spinning mill. The capacity of
a spinning mill is expressed by the number of spindles in the mill. On an
average the spinning mill of Bangladesh have 25,000 spindles. This may be up to
1, 00,000. Spindle is a combined unit makes up with spindle blade, wharve, and
lock/guard pin, bolster, bolster case etc.
Essential qualities of a spindle
a. Spindle must be perpendicular to the
rail bar on which they are mounted. Both the spindle and the ring should be
concentric to one another.
b. The spindle blade should never be allowed to
run with defective insert or bolster.
c. It should not vibrate during running.
d. It should run with minimum friction.
e. Should have precise construction with minimum
tolerance to ensure smooth and vibration free running with variable loads on
the bobbin as the yarn is wound on it under tension.
f. It should be cheap and durable.
g. It should be made up of corrosion resistance and
light material.
h. It should be well balanced.
Functions of spindle
a. To hold the bobbin
tightly to prevent slacking during its revolution.
c. To help in twisting
yarn.
d. Capacity of ring frame
mainly determined by the number of spindle.
Inverter drive for spindle
a. It is used to control the spindle speed.
b. It is used where change of spindle speed is needed
from time to time.
In this system, the inverter changes
the electrical frequency of AC motor. In an inverter drive spindle if we plot
bobbin dia against spindle speed we will obtain the following graph –
Normally, this curve is divided into
9 parts. In first and third part the spindle speed remain less, but there angle
of winding is small as bobbin diameter. So, end breakage increases. In next
fourth to seventh parts spindle speed increases. Again in 8th to 9th
parts spindle speed goes down.
In
inverter drive motor rpm can be found out by the following formula –
120f
Motor
rpm = …………….
P
Where, P = No. of poles
F = Motor frequency
The main advantages of this drive
system are that, here the increase or decrease in speed occurs in a step less
manner and the speed at which maximum production is obtained can be found out
easily.
Types and functions of traveler | Traveler size | Factors considered for selecting a traveler
Types of traveler
a) According to shape –
i. C –
Traveler (regular): It has horn.
ii.
Elliptical traveler: It has no horn.
b) Flat traveler
c) N – Traveler
d) SU – Traveler
e) According to wire cross
section –
i. Round
ii. Flat
iii.
Semi-circular
Among
the types, round and C travelers are mostly used for spinning finer count as
they give less friction. Flat and semi-circular travelers are used for coarser yarn.
Functions of traveler
a) Twisting the drafted
roving delivered through the front roller.
b) Helps in winding of yarn on to
the bobbin.
c) Maintaining winding tension
of the yarn by the frictional resistance between ring and traveler.
d) Acts as a guide for the yarn on
the way from ring to bobbin.
e) Performs the function of
building motion and also maintain spinning tension.
Traveler no. or traveler size
Traveler
no. expresses the wt. of traveler. It can be done in two ways –
a) Indirect system: Here the
unit is 10 travelers. If 10 travelers weight is 10 grain then, the no. is one.
If it is 11 grain then no. is 2 and so on. Again, if the wt. of 10 travelers is
9 grain then, traveler size is 1/0 or 1-0. If it is 8 grain then the size is
2/0 or 2-0 and so on. That is, if the no. is less, then the traveler is light.
In practice, travelers are available from no. 1 to 10 (Heavy traveler) and
reversely 1/0 to 20/0 (Lighter). Commonly, for finer yarn light traveler is
used and for coarser yarn heavy traveler is used.
A
general list showing suitable for different count of yarn –
|
Yarn
count(Ne)
|
Traveler
no.
|
|
16
|
2
|
|
20
|
1
– 2/0
|
|
30
|
3/0
– 4/0
|
|
40
|
6/0
– 8/0
|
|
50
|
10/0
– 12/0
|
|
60
|
13/0
– 15/0
|
|
80
|
16/0
– 19/0
|
|
100
|
19/0
– 20/0
|
This
chart is made by trial and error method. If suitable traveler cannot be chosen
then for heavier, end breakage rate will be increase and for lighter traveler
fly will be happened. At the same time, balloon size will also be bigger which
will increase the end breakage rate.
b) Direct system: Here every
individual traveler is weighted. Heavy wt. indicate heavy traveler.
Factors considered for selecting a
traveler
a) Yarn count : Ne ↑ traveler wt. ↓
b) Spindle speed : S S ↑ traveler wt. ↓
c) Ring dia : R D ↑ traveler wt. ↓
d) Empty bobbin dia : B D ↑ traveler wt. ↓
e) Ring condition : Condition ↑ traveler wt. ↑
f) Lift of
package : Lift ↑traveler wt.
↓
g) Traveler X-section : For round x-section heavy traveler
can be used.
h) Over all m/c condition: If
good, then comparatively heavy traveler can be used.
Factors to be considered for the selection of proper ring size
What are the factors to be considered for the selection of proper ring size? What are the advantages and disadvantages of large and small ring diameter?
The
selection of proper ring size depends on such prime factors as –
a. Spindle speed – Higher the spindle speed, smaller the ring dia.
b. Size of the bobbins – Larger the size of the bobbin, larger the
ring dia.
c. Types of bobbin – Heavier and larger
bobbins are adapted with larger ring size. Warp bobbins for larger ring size
and weft for smaller ring size.
d. Warp and weft – Larger ring size for weft and smaller ring size for
warp.
e. Yarn number – Higher the yarn number, lower the ring size.
f. Traverse of the thread board – Higher
the traverse of the thread board, larger the sing size.
Larger
ring size
Advantages
a. Larger package and fewer
knots which means better yarn quality.
b. Less cost of doffing,
spooling, winding, reeling etc.
c. Favors higher lifts
and therefore, larger yarn packages.
d. Easier manipulations for
the operatives.
e. Favors the spinning of
lower count yarn.
Disadvantages
a. Larger gauge of frame.
Hence, less spindles/frame and more floor space for more frames for a desired
mill unit.
b. Higher initial capital
investment for a desired mill unit.
c. Lower spindle
speed, lower front roller speed and hence lower production.
d. Requires heavier
traveller, hence greater frictional resistance causing more wearing out of the
rings etc.
Smaller
ring size
Advantages
a. Favors higher spindle
speed and higher front roller speed, hence higher production is possible.
b. Smaller gauge of frame
means more spindle/frame, hence less floor space is required for a desired mill
unit.
c. Less initial
capital investment for a desired mill unit.
d. Requires lighter
traveller, hence less frictional resistance causing less wearing out of the
rings.
e. Favors the spinning of
higher count of yarn.
Disadvantages
a. Smaller yarn packages
cause more knots, hence inferior yarn qualities.
b. More cost of doffing,
spooling, winding, reeling etc.
c. Shorter lifts and
therefore smaller yarn package.
d. Careful attention and
manipulation for the operators for smaller gauge of the frame.
The chief characteristics of the
spindle for good running conditions –
The following important characteristics
of the spindle should always be kept for good running condition –
a. It should
run with its vertical axis strictly perpendicular to the rail-base on which the
ring is mounted; both the spindle and the ring should be concentric to one
another.
b. The
spindle blade should never be allowed to run with defective insert.
c. It
should run well balanced.
d. It should
run with minimum friction and should have precise construction with minimum
tolerance to ensure smooth and vibration free running even with variable loads
on the bobbin as the yarn is wound on it under tension.
The plumbing and setting of the
spindle –
Correct plumbing of the spindle is very important art and requires a
skilled hand. This correct operation ensures longer life of the spindles as
well as the ring and travellers. The following steps are taken for correct
plumbing and setting –
a. That is
stopped, twist gear disconnected, bobbins are removed and the spindle assembly
(spindle blade, bolster cage and bolster insert) cleared from lint, thread etc.
b. Ring-rail
is brought drawn to the bottom position.
c. The
special bobbin that is provided with a circular collar having its diameter
about 1/8 th inch less than the diameter of the ring; the upper surface of the
collar should have white paint or some bright color which helps detections of
the clearance between the collar and the ring easily is mounted for correct
fitting of the spindle.
d. Then
looked down directly over the top of the spindle and seen for uniform clearance
by judging the intensity of light.
e. If the
clearance is not uniform, the nut which holds the spindles, base is loosen
slightly and the base is shifted by lapping gently with a wooden hammer to the
correct centre position.
f.
The ring-rail is raised to the top of the spindle and checked for uniform
clearance.
g. If not,
tilt the spindle for uniform clearance without disturbing the horizontal
adjustment.
h. When the
spindles are all plumbed, the thread guide is so adjusted that the contact
point of the thread on the back side of the thread guide is strictly vertical
on the centre of the top of the spindle blade.
This important operation should be done
regularly under schedule to maintain proper spring conditions.
Ballooning effect
What is ballooning effect? What are the factors, which effect the degree of ballooning and how can be controlled?
During spinning operation the drafted
strand of fibre being
delivered and held at one end by the front rollers, the other end rotates round
the bobbin with the traveller on the ring. It is observed that
the thread between the thread guide and the traveller, is bulged out which is
called the ballooning effect if the thread; and the balloon runs around the
bobbin at a high speed equal to the speed of the traveller.
The
following factors effect the degree of ballooning –
The
weight of the balloon length – The length of the yarn
which shows the ballooning effect is called the balloon length. The degree of
ballooning varies inversely as the wt. of the balloon length i.e. higher the
balloon length-weight, smaller the balloon size.
Yarn
count – The degree of ballooning varies directly with the
yarn count i.e. higher the yarn count, lighter the yarn and higher the balloon
size.
Speed
of the traveller – Higher the speed of the traveller,
larger the balloon size.
Weight
of the traveller – Lighter the traveller, larger the
balloon.
Atmospheric
resistance surrounding it – Higher the resistance, smaller the
balloon.
Frictional
resistance at the thread guide and at the traveller against the passage of the
thread – Higher this resistance, smaller the balloon size.
The effect of item no. 5 and 6 is little on
ballooning. The following measures may be taken to control the ballooning –
- The use of correct traveller size.
- The use of correct traveller speed.
- The use of separator or balloon guards between the two rings.
- By lowering the thread-guide rail to the correct position.
The causes of end down in ring spinning
Skewer –
Bad skewer ends or tips or any other fault which prevent the free rotation of
the roving bobbin.
Traverse guide on roving guider –
a. Traverse guide when
collecting fly blocks the regular passage of the roving.
b. No middle traverse guide
when using double roving.
Roving –
a. Bad piecing in the
roving.
b. Stretched roving.
c. Irregular roving.
d. More twist applied in the
roving leading to “shedding through” at the ring.
e. Single roving when using
double.
f. Neps or slubs
in the roving.
g. More waste in the roving.
Drafting zones –
a. Incorrect break draft.
b. Roller lapping.
c. Worn or grooved
roller.
d. Rust on the bobbin
drafting.
e. Worn aprons.
f. Pneumatic
system does not work properly so that the drafted strand of fibres fly entangles
with the side end and cause breakage.
g. Irregular distribution of
draft in the drafting zones.
h. Incorrect weight
distribution on the top roller.
i.
Improper weighting of the top roller.
j. Incorrect
setting of the drafting rollers in relation to the average staple length of
fibres under processing.
Lappet rail –
a. Incorrect setting of the
lappet is not at the straight line with the top of the spindle.
b. Dwell at each end of the
traverse of the lappet rail.
c. Starting up of the
m/c when the lappet rail is at the top position.
Ring –
a. Worn ring.
b. Grease or gum on and
under side of the ring flange.
Traveller –
b. Worn traveller.
c. Traveller flying
off.
d. No traveller clear
creating tufts of fibre on the traveller.
Spindle –
a. Lack of lubrication in
the bolster cage or insert.
b. Bent spindle is out of
centre of the spindle.
c. Excessive spindle
speed than that requires for the count.
d. Obstructed spindle speed
by accumulation of fibres beneath the spindle.
Bobbin –
a. Too larger or smaller
diameter of bobbin than that suitable for the count.
b. Jumbling bobbin.
c. Vibrating bobbin.
d. Badly worn bobbin in
which yarn tends to catch at the starting up.
e. Excessive full bobbin
which rub against the ring.
Tapes –
a. Bad joining of tapes
causing spindle vibration.
b. Tap ends flying off due
to badly sewing.
c. Slipping tapes.
Twist –
a. Use of higher or lower
twist multipliers than that requires for the count.
Other causes –
b. Flying fibres.
c. Incorrect relative
humidities.
d. Wind in the spinning
section.
e. Bad piecing up of the
yarns.
f. Shorter
staple when used for higher count.
g. Immature short or broken
fibres in the sliver.
h. Weaker fibres.
i.
Improper lubrication of the m/c.
j. Lack of
proper cleaning of the m/c floor.
k. Irregular maintenance and
over haul.
What are the faults found in Ring frame yarn? Give their causes
Soft yarn –
Generally caused by slack spindle bundles, twist change wheel too large, empty
bobbins not properly pushed down during doffing.
Uneven yarn –
Either travellers are too heavy or for spinning fine counts from inferior
cotton.
Twisty and brittle yarn –
Worn rings and travellers are too heavy or lack
of humidity in spinning room.
Rough yarn –
Traveller too light, too much twist, and spindle speed too low, bobbins that
are rough at the top.
Badly wound yarn –
Caused by the defective traveller motion and also by bobbin being loose on the
spindle.
Tender yarns –
Imperfect traveller, waste on travellers, adjustment of ring rail not correct,
thread guide not in the right position.
Hard and inelastic yarn –
Too much twisting and drafting in the draw frame
and also for insufficient doubling later.
Slub –
This occur when the twist in the yarn is not uniform. It appears as thick
place, which has received insufficient twist. This is caused by what is called
thick roving. Two rovings over lapping each other, which thus passing through
the rollers without receiving the amount of twist required.
Nepped yarns –
So called because it contains small piece of hard cotton called neps. These are
two kinds: Commonly distinguish as
natural neps and will neps. The former consists of short and undeveloped fibres
that have become embedded in the yarn. The latter are impurities and also short
fibres usually found adhering to the surface of the threads.
Classification of drafting system in the ring frame | Explanation of a modern system
Drafting
system can be broadly classified under two heads namely –
1. Regular drafting system
without apron. And
2. Drafting system with
apron.
The
system with apron can again be classified into three groups –
1. Single apron system.
2. Double apron system.
3. Multiple apron system.
Example
of regular drafting system without apron –
a. Conventional three roller
system.
b. Improved system.
c. H and B four
rollers long draft system.
d. 5 over 4 roller systems.
Example of single apron drafting system –
a. Saco – Lowell. Both
systems.
b. Saco – Lowell. Shaw
system.
c. Saco – Lowell. Z
system.
d. Toenniessen system. and
e. Versatex LS system.
Example
of double apron drafting system –
a. Casablancas double apron
system.
b. Casablancas “L” system
with flexible bar.
c. Saco – Lowell
thread rollers duo-Roth system.
d. SKF pendulum top arm
weighting system. And
e. Saco – Lowell 4 – roller
Duo – Roth system.
Example
of multiple Apron drafting system –
a. Casablancas “N” system.
b. Nittoh’s Semi-super high
draft system.
c. OM – S super high
draft system.
OM
– Super high draft system –
This system is specially designed to
spin direct from drawing sliver using special size small sliver cans in place
of usual roving bobbin in the creels as shown in the figure below fig. –
The back draft zone is in vertical
position and the front zone is inclined position to 500. The rollers
are spring weighted. In this system the back draft zone is equivalent to the
draft of a sliver and the drafting arrangement resembles to that of the long
draft sliver (Back, 4th and 3rd rollers). The front zone
(3rd, 2nd, and front roller) resembles the ordinary
Casablancas system.
It is claimed that, draft from 300 – 400
for count
of 60s – 80s and 150 – 250 for count 20s – 40s
can be obtained.
Ring –
The functions of ring are –
The functions of ring are –
b. The ring
act as a high speed bearing surface for the travellers.
c. One
may also conceive the behavior of the ring as a track for the traveller.
Traveller –
It performs the following functions –
a. Twisting
of the drafted strand of fibres as they are delivered by the front roller to
produce a yarn.
b. Winding
of yarn onto the bobbin.
c.
Maintain winding tension of the yarn by the frictional resistance between the
ring and traveller.
d. It acts
as a second guide for the yarn on the way to be wound on the bobbin.
e. It
performs the function of building motion to wind the constant length of yarn
delivered by the front roller. In speed frame bobbin r.p.m changes with the
increase of bobbin diameter but in ring frame the bobbin r.p.m remains constant
and the traveller r.p.m increases with the increase of bobbin diameter.
It
also performs many other functions involving highly complicated problems of
higher physics.
Creel –
The function of the creel is to hold the
roving bobbin over a roller beam within a convenient height to easily handle
the roving. The creel must permit free running of the roving bobbins with
slight tension on it.
Spindle –
a. The
spindle holds the bobbin somewhat loosely but tight enough to prevent any
slippage, so that the bobbin can be lifted out of the spindle with little
exertion.
b. With the
help of the ring and traveller the spindle inserts twist in the yarn being
delivered by the front roller.
c. It
also carries out another important function of winding the twisted thread on
the bobbin with the help of ring and traveller.
Roving guide –
The guides are mounted at the right
angle to the flat bar called traverse bar. The object of the guide is to feed
the roving correctly at the bite of the back roller and the traverse motion
moves the strand almost over the entire length of the bite and this prevents
the drafting rolls from being grooved at a particular place.
Lappet motion or thread board
traverse –
The main function of the thread board
traverse is to maintain the balloon size within the controlling range. To keep
the balloon length within the controlling limit, the thread board is
necessarily be made to traverse relative to the ring rail. For 8” lift bobbin
the traverse of the ring rail is more or less confined within the range from 1”
– 1.5” and higher traverse for higher lift of the machine.
The slow traverse of lappet-rail also
facilitates the easy passage of the yarn from the front roller to the bobbin.
Explain the factors for the limitation of modern ring frame for higher production
Explain the factors for the limitation of modern ring frame for higher production | What are the important setting points in ring-frame?
The
factors which put limitation for higher production in ring frame are –
Maximum traveller speed –
It is limited by the types of ring flange, style of traveller, wt. of traveller and rate of traveller
run.
Maximum roller delivery speed –
The limiting factors beings the ability of the operative to piece-up the broken
ends and the limitation of the drafting system to control fibres.
Yarn tension in the balloon –
The limiting factors being sufficient strength in the processed yarn to
withstand the tension imposed by the traveller and balloon. The amount of twist
can alter the yarn strength irrespective of type and staple of fibres.
Balloon collapse –
It is caused by operating with high spindle speed and low traveller weight.
Yarn strength being enabled to support a heavy traveller.
Limitation of drafting system
Final requirements of spun yarn
What
are the important setting points in ring-frame?
The
important setting points are –
1. Roller setting.
2. Lappet rail setting.
3. Lappet snarls setting.
4. Spindle rail setting.
5. Spindle setting.
6. Ring rail setting.
7. Setting of the building
mechanism.
8. Setting of the fulcrum
for different tapper shapes.
9. Setting of the roving
guide traverse motion.
10.
Setting of the top roller angle with the bottom roller.
11.
Adjusting top roller pressure on the bottom rollers.
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