The document discusses the roving frame machine used in textile manufacturing. It begins by explaining the necessity of the roving process and the objectives of the roving frame. The key parts and operating zones of the machine are then described, including the creel, drafting arrangement, twist insertion via the flyer and spindle, and winding of roving onto bobbins. The document provides details on the operating sequence, process parameters like draft and twist levels, and the mechanical drive systems used in the machine.

1. Roving Frame
By Bewuket Teshome (Lecturer)
Bahir Dar University

2. 1.1. Introduction
1.2. Operating sequence
1.3. The operating zones of the roving frame
1.4. Machine drive systems
1.5. Automation
1.6. Process parameters and production calculation

3. Today’s Objectives:
 To understand the necessity of roving process
 To understand the objectives of roving frame
 To know the working principle of roving frame
 To understand false draft and its cause
 To identify the creel and the drafting arrangement
components
 To understand the principle of drafting
 To understand the difference between draft and
attenuation
 To understand the importance of all components in the
drafting zone
 To identify the different roller weighting systems
 To understand the cradle length

4. 1.1. Introduction
Draw
Frame/Comber
Roving
• Drafting
• Twisting
• Winding
The draw frame sliver already
exhibits all the xs required for
the creation of a yarn.
Fibers
Ordered,
Clean
 Laying parallel

5. Why roving frame is necessary?
• The required draft. Sliver is a thick, untwisted
strand that tends to be hairy and to create fly. The
fine, twisted roving is significantly better suited to
this purpose.
• The draw frame cans represent the worst
conceivable mode of transport and presentation
of feed material to the ring spinning frame.

6. Objectives of the roving frame
• Drafting: The chief task of the roving frame is the
attenuation of the sliver.
• Twisting: since the resulting fine strand has
scarcely any coherence, protective twist must be
inserted in order to hold it together.
• Winding: winding the roving into a package that
can be transported, stored and donned on the ring
spinning machine.

7. 1. Sliver can
2. Driven
transport rollers
3. Drafting
arrangement
5. Roving
6. Flyer
7. Spindle
8. Bobbin
9. Bobbin rail
10. lever
.
1.2. Operating sequence

8. • Draw frame sliver is presented to the roving frame in
large cans (1).
• Driven transport rollers (2) draw the slivers from the
cans and forward them to drafting arrangement (3).
• The drafting arrangement attenuates the slivers with a
draft of between 5 and 20.
• The strand delivered is too thin to hold itself together.
• A protective twist is inserted , usually in the range of
25 – 70 turns per meter. The turns are created by
rotating flyer (6) and are transmitted into the
unsupported length of roving (5).
• The flyer itself forms part of driven spindle (7) and is
rotated with the spindle.

9. • The roving runs through the flyer top and the hollow
flyer leg to the wind-up point, and is wound 2 – 3
times around the presser arm before reaching
bobbin (8).
• To enable winding to be performed, the bobbin is
driven at a higher peripheral speed than the flyer so
that the roving is drawn off the flyer leg.
• The coils must be arranged very closely and parallel
to one another so that as much material as possible
is taken up in the package. For this purpose, bobbin
rail (9) with packages on it must move up and down
continuously.
• This can be affected, for example, by continual
raising and lowering of lever (10), on which the
bobbin rail is mounted.

10. 1.3. Operating/Working regions of the roving frame
 The creel
 The drafting arrangement
• Roller drafting system
• The apron
• Applying pressure to the top roller
• The condenser
• The spacer
 Winding of bobbin
• Package build
• Bobbin drive
 Cone drive transmission
 The lifter motion
 The builder motion
Spindle & flyer
• Imparting twist
• Spindle
• Flyer
• Design of flyer
• Pressure arm

11. Due to high degree of parallelization
of the fibers in the slivers (especially in
the case of combed sliver), strand
coherence (sticking together) is often
not very great.
 Accordingly, transport at this place
can easily create false drafts.
Guide rollers should run smoothly to
avoid false drafts.
Above the cans there are several rows of driven rollers to help the
slivers on their way to the drafting arrangement.
A perfect drive to the rollers is effected by chains.
The Creel

12. The drafting arrangement
Draft?
•The distribution of an approximately constant total number of fibres
over a greater length of the product.
•Drafting is effected mostly on roller drafting arrangements.
•The fibres are firmly nipped between the bottom steel rollers and the
weighted, top, pressure rollers.
•The rollers are so rotated that their peripheral speed in the through
flow direction increases from roller pair to roller pair, then the drawing
apart of the fibres, i.e. the draft, takes place.
Attenuation?
Attenuation = Draft * 100
(100-P)

13.  Double apron drafting system with 3/3 or 4/4 (for high
drafts) roller arrangements
 It is used in the roving frame since it enables drafts of 20
while holding the fibers more or less under control during
their movements.

14. Three-cylinder, double-apron drafting arrangement

15. Drafting Rollers
Bottom drafting rollers
They are usually fluted.
They get motion from motor.
They are not continuous, connected together by roller bearing.
Knurled
Spiral
Plain

16. Top drafting rollers
They are rubber coated pressure rollers.
• Hardness = 80 – 85o Shore,
• Rollers over which the apron runs often have a hardness
only slightly greater than 60o Shore to enable better
enclosure and guidance of the fiber strand during drafting.

17. • The top rollers are pressed down with sufficient force on to the
bottom rollers to ensure proper grip of the fibers so that there will
be proper guidance of the fibers.
• Pressure are in the range of 100 to 250 N per roller which may
vary as per raw material and its volume.
• Top roller weighting can be carried out by:
• Spring (all manufacturers)
• Pneumatic pressure (Reiter)
• Spring + magnet

19. Condensers
• At the back of back roller they are mounted on a reciprocating bar.
• The traverse motion spreads wear evenly over the whole width of the roller coatings.
• In the main drafting field which rest on the moving fiber strand without being fixed.
Function:
• Spreading sliver masses are condensed to improve evenness and lead to drafting
zone.
Advantage:
• Reduce the high fly level and hairiness of roving.

20. Aprons
They are made of leather or synthetic rubber. They are usually
about 1mm thick.
The upper aprons are short.
The lower aprons are longer. They run over the guide bar, usually
known as nose bar, to position close to the delivery roller.
They are used to guide and transport fibers during drafting.
They should extend as closely as possible to the nip line of the front
rollers.
The guiding length, referred to as the cradle length, must be
adapted to the staple length.

21. •They are held taut by tensioning devices (4).
• In contrast, the lower aprons (1) are longer and
usually made of leather, although synthetic rubber is
also used.
•They run over guide bars (nose bars) (3) to positions
close to the nip line of the delivery rollers.
Cradle L
(mm)
Cotton
36 29-31 mm
43 32-39 mm
50

22. Spacer
• As the top apron are forced by spring pressure against the
lower apron, the arrangement of this apron should permit
precise adoption of minimum distance to fibre volume.
• In order to be able to maintain this minimum distance,
spacer are replace ably inserted between the nose bar of
the lower apron and the cradle edge of top apron.
• Spacer size is 4 to 7 mm in accordance with roving hank.

23. In the roving frame we can witness two drafting zones
1. Break draft (at the back zone)
• The main objective is to enhance the fiber orientation instead of
drafting itself.
• 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.
• Break draft affects roving evenness.
2. Main draft (where the real drafting is taken place)
• The total draft is the product of break and main draft.
Maximum Total Draft = 20
Minimum Total Draft for cotton = 5 and for synthetic fibers = 6.
• If drafts below lower limits are attempted, then the fiber masses to be
moved are too large, the drafting resistance becomes too high and the
drafting operation is difficult to control.

24. Reading Assignment One
Make a note on
Bottom apron tensioner
Drafting Clearer
Suction system

25. Today’s Objectives:
To understand the principle of twisting
To identify the twist inserting parts and their
technological impact on the roving
To understand the effects of arrangement of
bobbins into two rows

26. Imparting Twist
TWIST: The number of turns about its axis per unit of length
of a roving or other textile strand.
• Twist is expressed as turns per inch (tpi), turns per meter
(tpm), or turns per centimeter (tpcm).
• Twist per unit length depends on the delivery rate of front
roller.
Twist per inch (TPI) = rpm of flyer
s s of front roller (inch/min)

27. Spindle
• It is a long steel shaft mounted
at it’s lower end in a bearing.
• It is a support and drive element
for the flyer.
• The spindle tip is conical and is
provided with a slot.
• When the flyer is set on the
spindle cone, a pin on the flyer
projects into the slot so that the
flyer and spindle are converted
into a unit for drive purposes.

28. The Flyer
• Flyer has two legs, one with
hollow path or slot and presser
arm another for balancing the
flyer while rotating.
• Flyer is placed on spindle, it
gets motion by gearing.
• Flyer speed has direct
influence on production.
• Flyer can be varying in sizes
which are specified in inch. For
example, 12”X 5.5”, 12”X6”
and 14”X6” (max. height X
max.dia. of package)
1. Flyer top
2. Roving inlet
3. Spindle end
4. Flyer leg
5. Presser arm
6. Presser eye
7. Spindle

29. Functions of the flyer:
1.Inserting twist
• Each flyer rotation creates one turn in the roving.
• The flyer rotation rate is held constant.
• High levels of roving twist always represent
production loses.
• Low twist levels can cause roving breaks during
bobbin winding.
2.Leading the very sensitive strand from the flyer top to
the package without introducing false drafts.

30. • This is very difficult task because:
i) The strand has only protective twist and is very liable to
break;
ii) The flyer, along with the roving, is rotating at a high rate (up
to 1500rpm).
• The fiber strand must, therefore, be protected against strong air
currents.
• For this purpose, one of the two flyer legs has been grooved, i.e.,
open in a direction opposite to the direction of rotation.
• New designs are no longer provided with this easily accessible,
“service-friendly” groove.
• Instead, they have a very smooth guide tube set into one flyer leg.
• The advantages are: the strand is completely protected against the
air flows and frictional resistance is significantly reduced so that
the strand can be pulled through with much less force.
• These reduce false drafts and strand breaks while allowing high
production speeds.
• The disadvantage is that piecing of strand break is difficult.

31. Presser Arm
• A steel end attached to the lower end of
hollow flyer leg is called presser arm.
• The roving is wrapped 2 or 3 times
around it.
• The no. of turns determine the roving
tension.
• For higher tension, a hard compact
package is obtained and if it is too high
false draft or roving breakage can be
caused.
• Therefore, the no. of wrap depends upon
material and twist level.

32. The flyer top
• The way in which the roving is carried
along and guided at the entrance to the
flyer determines the degree of twist and
the winding tension.
• low twist or coarse, the strand passes
through the flyer top to the guide
groove without wrapping.
• A half-turn of wrap is selected for high
speed frames winding large packages
with high twist levels.
• The wrap enables better control of
roving tension and the package build
becomes more even owing to harder
coils.
• Old flyers have flyer tops of smooth
metal.
• Modern flyers have an insert of rubber
formed with grooves.

33. Effect of Arrangement of Bobbins in two
Rows
• In fly frames, the spindles are arranged in two rows (in
a zigzag manner).
• This arrangement is made in order to economise on the
space requirements.
• It has some technological disadvantages.

34.  The free unsupported lengths (L1 & L2) are different.
(Fig. (a)).
 The rolling angles (β) are different (Fig. (b)).
 The spinning triangle sizes are different.

35.  These differences result in:
 More complicated design
 Operation of the machine is made less convenient
 Automation is hindered
 uneven twisting
 uneven binding of fibres and
 ultimately count variation between front and back rows.

36. Various designs of the flyer
Depending upon its form and drive, there are three flyer types:
1. Spindle mounted flyers:
 Simple as far as design and drive are concerned.
 Piecing is easier.
 automation is difficult.
2. Top-mounted (suspended) flyers:
•Facilitates automation of the doffing operation,
•piecing is difficult.
3. Closed flyers:
Reduced spreading of the legs at high operating speeds.

37. Today's Objectives
To understand the principle of winding
To identify parts involved in winding process
To understand the motions/movements
involved in cone winding process (Builder
motion)
To understand the drive elements for the parts
involved in cone winding process

38. Winding Principle
Winding is the process of transferring roving from flyer to
roving bobbin to facilitate subsequent processing.
• Cylindrical body with tapered ends.
• Created by building layer upon layer
of parallel coils of roving.
• The angle of taper of the ends is
normally between 80° and 95°.
• Large angle - to wound more roving
onto the package.
• Small angle - to ensure that the
layers do not slide apart. [Slough-off]

39. Mechanical drive systems
Electronic drive system
To create the desired shape the following motions
are required;
Bobbin
Rotation – to wind the roving on the roving bobbin
[bobbin speed must be higher than the flyer speed]
Reduction of rotation by belt shifting– to achieve
constant winding speed
[bobbin dia. increases, the winding on speed must be
decreased-constant]
Bobbin rail
Lifter motion - to wind over the whole length of the
tube, the winding point must be continually shifted.
Reversing the direction of movement
Shortening of traverse/stroke after each layer has
been completed – to make tapered ends.

40. Let,
 Front roller delivery= L inch/min
 Bobbin speed at any instant point of winding = NB rpm
 Spindle speed at any instant point of winding = NS rpm
 Bobbin dia. at that point of winding = d
So, bobbin circumference = d
Winding on speed, Nw = (NB – NS) rpm
Total winding length / minute = d (NB – NS)
Therefore, L = d (NB – NS)
In this formula, L,  & NS are constants. So, with the
increase of bobbin dia, bobbin speed decreases..

41. 1.4. Mechanical drive system:
41
Bobbin drive:
•Variation in bobbin speed originates from the cone drums.
•When the builder motion shifts the cone belt, the rotation
speed of the lower cone is changed.
•This declining rotation speed is transmitted via gearing to
the differential and superimposed on the constant speed of
the main shaft.
•Further gearing then transmits the resulting rotation speed
to the bobbin drive.

42. Bobbin drive (side view);
drive transmission to the
bobbin
Bobbin drive (gearing plan) 42

43. Cont…
• On the bobbin rail, bevel gears fixed to the
longitudinal shaft drive the bevel gears of the
bobbin supports.
• Flexible connection is needed between the main
drive shaft in the gear box and the longitudinal
bobbin shaft- swinging joint.
43
Swinging joint at the bobbin drive shaft

44. Cont…
Cone drive transmission
• Transmission occurs in small steps through shifting of
the cone belt after each lift stroke.
• Bobbin rotation must be changed with a linear
function.
• Straight-sided cones does not vary the transmission
ratio in a linear manner and thus does not produce
the required linear variation in bobbin rotation speed.
• The cone faces convex on the upper driving cone and
concave on the lower driven cone - difficult to design.
• Straight sided - the belt must be shifted through steps
of varying magnitude, the initial steps being relatively
large ( W1) and the later ones smaller.
44

45. Convex and concave cones
Shifting the belt with hyperbolic (a) and straight-sided cones (b)
45

46. Shifting the belt
• Is controlled by the ratchet wheel (on axle).
• After each stroke, the ratchet wheel is permitted to rotate
by a half tooth.
• This ratchet steps out the wire rope (1) and hence permits
movement of the belt guide (5) to the right.
• The tensile force required to induce movement of the belt
is exerted by a weight.
• Bobbin diameter increases more or less rapidly depending
upon roving hank.
• So degree of shift is modified by replacing the ratchet
wheel or by substituting change wheels.
• ratchet wheel with fewer teeth - then the belt is shifted
through larger steps, i.e. it progresses more rapidly, and
vice versa
• When the bobbin is fully wound, the belt must be moved
back to its starting point- today by auxiliary motor.
46

47. Belt-shifting device
47
1. Rope
10. Ratchet wheel
5. Belt guide
7. Weight
4. belt

48. Bobbin rail
a. Lifter motion:
• In the package, each turn must be laid next to its neighbors.
• So the lay-on point must continually be moved, by raising
and lowering the bobbins supported on a movable rail.
• Not by raising and lowering the flyers – b/c the
unsupported roving length, withdrawal angle and
approaching angle will vary.
• Raising and lowering can be carried out by –
- Racks attached to the rail.
- Lever mounted on the rail
• The lift speed must be reduced by a small amount after
each completed layer.
• The lift drive is also transmitted via the cone transmission
as bobbin drive but not via the differential.
48

49. Lifter motion with racks (a) Lifter motion with levers (b)
49

50. b. Reversal of the bobbin rail movement:
• Reversing drive must be provided so that the bobbin rail is
alternately raised and lowered.
• Reversal of the rail movement originates from the reversing gear
(1/2/3).
• Electrically operated valve pressurizes the left- and right-hand
chambers of double-acting cylinder (9) alternately.
• Thus left-hand clutch (1) and right hand clutch (2) are operated
successively.
• So that pinion (3) engages with either gear wheel 1 or gear wheel
2.
• The rotation itself comes from the shaft 10, on which gear wheels
1 and 2 are mounted, always rotating in the same direction.
• Operation of clutch (1) or (2) causes left- or right-hand rotation of
pinion 3 and shaft 4, accordingly.
• The bobbin rail is correspondingly raised or lowered via bevel gear
5, pinion 6, sprocket 7 and lifting chain 8.
50

51. a. The reversing assembly of the lifter motion
b. Mechanism for reversing the bobbin
rail movement
51
1/2/3 – reversing gears
4 – shaft
5 – worm gear
6 – pinion
7 - sprocket
8 – lifting chain
9 – cylinder
10 – drive shaft

52. c. Shortening the lift:
• Rods 5 and 6 (a) are inclined.
• The inclination is adjustable and corresponds exactly to the taper of the bobbin
ends (angle alpha).
• During winding of a package, the ratchet is rotated at every change-over, and the
micro-switch (4) is also gradually shifted further to the right on a slide.
• Therefore, the rods engage the micro-switch steadily earlier in the lift stroke,
reversal occurs correspondingly earlier.
• This results in a continuous reduction in the lift of the rail. The bobbins are thus
built with a taper.
c. The assembly for building conical ends on the bobbins 52
1- Bobbin rail frame
2 – bobbin rail
3/7 – bracket
5/6 – rods
4 – micro switch

53. Builder motion
Has to perform three important tasks during winding
• Shift the cone belt corresponding to the increase in
bobbin diameter;
• Reverse the direction of movement of the bobbin
rail at the upper and lower ends of the lift stroke;
• Shorten the lift after each layer to form tapered
ends on the bobbins.
53

54. Today's Objectives
 To understand electronic drive system and its advantage
 To identify possible automation areas in roving frame
 To understand the process parameters in roving frame
 To understand how production is calculated in roving
frame

55. Electronic drive system
• Electronic devices - frequency converters and
individual servomotors - enabled the drive system of
the roving frame to be simplified.
• Spindles and flyers are driven directly by individual
servomotors.
• The control system ensures synchronized running
throughout package buildup.
• The drives are controlled by frequency converters and
are thus especially gentle in their treatment of the
material.
• Controlled machine stop is assured in the event of
power failure.
55

56. Electronic drive system
56

57. Advantages of Electronic Drive System:
Much simpler than mechanical drive versions
Lower energy consumption and reduced
maintenance
No need of heavy counter weight for bobbin rail
balancing and differential gear,

58. 1.5. Automation
replacement of human workers by technology: a
system in which a workplace or process has been
converted to one that replaces or minimizes
human labor with mechanical or electronic
equipment.
• Cleaning: by means of cleaning aprons, clearer
rollers and suction systems at the drafting
arrangement and also by the traveling blowers
that keep the machine clean.

59. Equal roving geometry for
front and back row roving
 Deposition of roving spindles
in two rows leads to variation
in roving twist and count.
 Modern speed frames have
raised flyer top of the back
row as compared to the front
row to maintain the roving
delivery angle.

60. Roving tension sensors
These tension sensors do
not actually contact the
roving while measuring
the tension.
The tension is measured at
periodic intervals.
The required change in
tension is actuated by
changing the bobbin speed
through servomotor.

61. Bobbin doffing:
Manual:
 Costly
 Frequent and time consuming
 labor intensive
 Ergonomically unsatisfactory
decreases efficiency
Automatic:
 reduction in doffing time.

62. Bobbins transport
Manual Transport:
Labor-intensive
Damage to the roving
60 % wages cost can be attributed to cost of
transport
Automatic transport:
 Reduced labor costs
 Roving bobbins are not touched, the bobbin surface is not
damaged substantial increase in quality and productivity
 No intermediate storage which might result in damage,
soiling, or ageing of the roving, space-saving
 No confusions between different roving bobbins ensuring
the application of the “first-in, first-out” principle
 Clearly structured material flow, speeding-up processes

63. Machine monitoring (stop motions)
• In case of roving or sliver break machine should stop
immediately in order to avoid production loss and creation
of faults in the roving.
Sliver stop motion:
By light emitter and photocell
• Located between the last transport roller of the creel and
the drafting system
• m/c should stop , in case of sliver break
Roving stop motion:
Light beams fall on flyer tops
• In case of a roving break, broken roving ends whirl around
(hood), Interrupts light beam, m/c stops
• Production monitoring by Zellweger Uster: records,
evaluates and stores interruptions in operation of all
machines in the preparatory installation.

64. Reading Assignment two
Make a note on
Other Possible places for Automation

65. 1.6. Process parameters and production calculation
Parameter: variable quantity determining outcome, a measurable quantity.
Process parameters
• Speed of rollers (draft)
• Diameter of rollers
• Roller setting
• Pressure (100 – 300 N) Pressure range for pneumatic (1.5 bar-5 bar)
• Speed of flyer/spindle (twist)
• Speed of bobbin (winding)
• Condenser size
• Spacer size
• Shore hardness
• Cradle length
• Number of spindles/flyer
• Twist multiplier
65

66. Cradle length (mm) Cotton Synthetic fibres
36 Cotton up to 29-31 mm 40mm
43 Cotton up to 32-39 mm 50mm
50 60mm
Roving hank (Ne) Condenser size (mm)
Below 0.8 10
0.8-1.0 8
1.0-2.5 6
2.5-6 4
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

67. Production calculation
•Feeding Rate = π * D(dia of back roller) * Rpm(back roller)
•Delivery Rate = π * D(dia of front roller) * Rpm(front roller)
•TPI = TM
TPI = spindle speed________________
Delivery rate or F.R delivery in inches/min
Production(lbs/hr) = front roll delivery * 60 * 1 * ŋ
36* 840 * count
Production(lbs/hr) = flyer rpm * 60 * No. of spindles * ŋ
TPI * Hank roving * 36 * 840

68. Example: Find out the production per shift of a modern speed frame
at 85% efficiency to produce 1.5 hank roving. Assume necessary
parameters.
Given, Efficiency=85%, Roving hank=1.5Ne
= 1.1*
No. of spindle = 120, Spindle speed = 1200 rpm.
Production =
Spindle speed*no. of
spindle*hr*shift*efficiency / TPI*36*840* hank
= 1200*120*60*8*0.85/ 1.34*36*840*1.5
= 96.6 lbs/shift (Ans)
Let, TM = 1.1
TPI = TM
=1.34

69. Thank You!!!