3. Introduction
The roving frame is the machine that comes after the draw
frame in short-staple spinning system.
The input is the finisher draw frame sliver in sliver cans and
the output of the roving frame is called roving.
The roving frame is called by various names in the industry
and in the literature.
The machine is called a fly frame or a flyer frame - as it
employs a flyer, simplex, speed frame.
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4. The draw frame produces a sliver that already exhibits
all the characteristics required for the creation of yarn,
Namely an ordered, clean strand of fibers lying
parallel to one another.
In fact, the roving machine is :
Liable to faults,
Causes defects,
Adds to production costs and delivers a product
that is sensitive both in winding and unwinding.
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5. Two principal reasons for the use of
roving frame are:
1) The required high draft in the ring frame (DT
= 300 – 500), and
2) Draw frame cans are not convenient for
transport and presentation of feed material to
the ring frame.
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6. Objectives of Roving frame
To draft the sliver to a thin strand,
To impart to the drafted strand a protective
twist and
To wind the drafted and twisted roving
material onto a suitable package for further
use.
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7. Operating Sequence
The draw frame sliver cans are arranged in 4 or 6 rows in the
creel zone and the sliver from each can is fed to the drafting
system.
The drafting system drafts the sliver to a fine strand of
material ready for twisting.
The draft usually employed in fly frames ranges from 5 to 20.
Coarser roving need less and finer roving need higher drafts.
The delivered roving has a hank (or, count) in the range of
about 1s to 3s Ne.
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9. The material delivered from the drafting system is
led to the top of the flyer.
From the front roller nip to the flyer top, the
material remains unsupported.
From the top of the flyer, the material is guided
through one of the legs of the flyer; at the bottom of
the leg of the flyer, the material is wound on the
presser (usually two or three turns around the presser
arm).5/29/2017 9
10. The material is then passed through the eye of the
presser from which point, it can be wound onto the
package.
The strand delivered by the drafting system is thin
and weak.
Therefore, a protective twist - of the order of about 1
to 3 turns per inch is given to the strand before
winding it onto a wooden or plastic package.
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11. The flyer imparts twist to the delivered
material by its rotations.
One rotation of flyer imparts one turn of
twist to the delivered material.
The flyer is mounted on the top of a
spindle.
The spindle and flyer rotate together.5/29/2017 11
12. The flyer rotates at a constant speed.
The most common speeds employed range from
about 1000 to 1500 revolutions per minute.
The twisted roving is wound onto the surface of
the bobbin in the form of closely spaced helical
coils.
Each of the spiral coils is spaced close to each
other i.e. the coils touch each other.
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13. To effect winding in this manner, the roving
bobbin is moved up and down.
Once a layer of roving has been wound, the
direction of movement of the bobbin is
reversed and a fresh layer is wound over the
previous layer.
The process continues till the bobbin is full.
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14. The bobbins and the associated driving gears are
placed in a bobbin rail; the spindle and the associated
driving gears are housed in the spindle rail.
The spindle rail is stationary.
The bobbin rail along with the bobbins moves
vertically up and down during the running of the
machine to enable winding of the material in
traverses.
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15. To effect winding of material onto the bobbin, the bobbin
has a rotational speed which is equal to flyer speed plus the
additional rotations for winding.
As each layer is completed, the diameter of the bobbin
increases.
This would mean that the additional rotations required for
winding have to be reduced after the completion of each
layer.
Note that the delivery rate from the drafting system remains
constant.
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17. The creel
Above the cans there are several rows of driven rollers to
help the slivers on their way to the drafting arrangement.
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18. The Drafting Arrangement
A. Double apron drafting system with 3/3 or 4/4 (for
high drafts) roller arrangements:
Is used in the roving frame since it enables
drafts of 20 while holding the fibres more
or less under control during their
movements.
B. 3-over-4 drafting arrangement: used relatively
rarely since it gives less drafts.5/29/2017 18
19. Maximum Total Draft = 20
Minimum Total Draft for cotton = 5 and
for synthetic fibers = 6.
Break drafts for cotton = 1.05 – 1.15 (usually 1.1), and for synthetics
and strongly compressed cotton sliver delivered from high
performance draw frames = 1.3.
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20. Aprons
They are made of leather or synthetic rubber.
used to guide and transport fibers during drafting.
They are usually about 1mm thick.
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21. Spindle and Flyer
The spindle is simply a support and drive element
for the flyer.
The spindle tip is conical and is provided with a
slot.
Functions of the flyer:
1.Inserting twist ,Twist = Flyer rotation rate
Delivery speed
2.Leading the very sensitive strand from the flyer
top to the package
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22. Build up of the bobbin
A roving bobbin is a cylindrical body with tapered ends.
The angle of taper of the ends normally lies between 80o
and 95o (maximum 100o), and depends upon the adherence
of material.
The angle is made as large as possible to wound more
roving onto the package.
However, the angle must be small enough to ensure that the
layers do not slide apart.
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24. Laying down of roving in the package is effected in parallel
layers, i.e., each wrap is laid on wooden or plastics tubes
closely adjacent to the neighbouring wrap.
To wind over the whole length of the tube, the winding point
must be continually shifted.
This is achieved by:
1) Raising and lowering the flyer or
2) Up and down movement of the tube together with
the bobbin rail (by means of racks or lever).
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26. Variation in bobbin speed originates from the
cone drums.
When the builder motion shifts the cone belt,
the rotation rate of the lower cone is changed.
This continuously reducing rotation rate is
transmitted via gearing to the differential and is
there superimposed on the constant speed of
the main shaft.
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27. Further gearing then transmits the resultant
movement arising in the differential to the
bobbin drive.
Furthermore, in order to prevent falling away
of individual layers, the bobbin ends are made
conical and consequently the lift of the bobbin
rail has to be reduced after each stroke (layer).
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28. For winding and controlled twisting of the roving to a
selected degree, the flyer and the bobbin must have
the same sense of rotation.
However, the bobbin must rotate faster than the flyer
(leading bobbin) or the flyer faster than the bobbin
(leading spindle).
Advantage of leading spindle:
With a preset fixed spindle speed, the operation can be run
with lower bobbin speeds – lower than the spindle speed.
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29. Advantages of leading bobbin are:
1. Fewer roving breaks or faultily drafted places at the
winding point because the drive transmission path from the
motor to the spindle is short, whereas that of the bobbin is
long
2. No unwinding of the layers during roving breakage and
3. Speed reduction with increasing package diameter.
However, with a leading spindle, the bobbin speed must be
gradually increased with increasing package diameter
which demands more power.5/29/2017 29
30. The builder motion
It performs three important tasks during a winding
operation:
1. Shifts the cone belt corresponding to an increase in
the bobbin diameter
2. Reverses the direction of movement of the bobbin
rail at the upper and lower ends of the lift stroke,
and
3. Shortens the lift after each layer to form tapered
ends on the bobbins.5/29/2017 30
31. m
rts
R
T
TNnE
P
39
1060
Production Calculation
The production rate of a speed-frame is dependent
on:
the spindle speed of the fly,
the number of spindles per machine,
the production efficiency,
the roving count, and
the twist multiplier used.
The following equation gives the calculated
production rate.
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32. Where:-
PR = production rate (kg/h)
TM = twist multiplier (turn m-1 tex1/2)
E = machine efficiency (%)
n = number of spindle per machine
Ns = spindle speed (rpm)
Tt – r = roving count (tex)
TPI = TM* (Indirect system)
TPI = TM/ (direct system)
Roving count (Ne) TM
0.8-1 1.3
1.1-1.2 1.2
1.3-1.5 1.1
1.6-2.0 1
2.1-4 0.9
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33. Faults and Causes:-
a) Unequal tapering:
Causes: i. Faulty building motion setting.
ii. Damage in poker wheel teeth.
b) Soft Bobbin:
Causes: i. Low winding on speed.
ii. Low winding on tension.
iii. Less no. threading on the pressure arm of the
flyer leg.
c) Excessive roving breakage:
Causes: i. More flyer speed.
ii. Roller lapping.
iii. Too closing setting of drafting roller.
d) Slubs (High/ abnormal thick place):
Causes: i. Bad piecing
ii. Improper setting of drafting roller.
e)Irregular roving (mass per unit length variation).
Causes: i. Improper setting of drafting roller
ii. Fault is top rubber coated rollers.
f) Sloughing off: over lapping of coil of roving.5/29/2017 33
34. Recent developments of roving
frame/ simplex:
Flexibility in drafting system
Top and Bottom clearer device with suction.
Delivery speed -----------------------------------up to 40 mts/min.
Spindles per machine ---------------------------48 - 160
Flyer rotation speed, rpm-----------------------up to 1 500
Production rate, g/sp.h--------------------------250 - 2 000
Sliver hank, ktex----------------------------------3.8 - 5.5
Roving hank, tex----------------------------------170 - 1 500
Draft------------------------------------------------5 - 22
Bobbin weight, kg---------------------------------up to 3
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