Frictional Drive in Textile
Part 1:Drum drive, belt drive
and chain drive
Frictional Drive
1. What is frictional drives
2. Types of frictional drives
1.
2.
3.
4.
Drum drive (eg cheese winding)
Belt drive (spinning, weaving)
Vee-belt drive (motor power )
Chain-and-sprocket drive
1) Frictional Drives
• Many drives for textile machines rely on
the friction between the driving element
and the driven element. Examples:
– Belt and rope drives;
– Drum drives to cone in yarn preparation
– Drum drives to warping beams
• The common feature is one element has a
hard surface and the other is a relatively
soft surface
Drum Drive
Driven
Driver
Cone winding is a typical example of frictional drive
Drum drive
• Figure 1 shows the cheese sits on top of
the drum (driven).
• The surface speed of drum (driver) is
V=n1 x pi x d1
• Assume no slippage between the drum
and cheese, the surface speed will be:
• n1 x pi x d1 =n2 x pi x d2
• n1 /n2 = d2 /d1
Drum drive
• The last equation shows that the ratio of
the rotational speeds of the two elements
is the inverse ratio of their diameter.
• It should be noted that the running speed
(rev/min) for the empty cheese (smaller
diameter) is higher than full cheese
(bigger diameter).
Example
Calculation for cheese winding
Question 1
• A drum has 12cm diameter and
rotates at 2650 rev/min., find out
– A) the actual winding rate (m/min)
– B) the rev/min of the cheese at start
(empty package)
– C) the rev/min of the cheese at 18cm
diameter (full package)
Answer 1
• 1) Actual winding rate:
– V= n1 x pi x d1
– V= (2650 x 3.14 x 12)/100 =1000 m/min
• 2) Rev/min at start:
– n1 x d1 x pi = n2 x d2 x pi
– 2650 x 12 = n2 x 5; n2=6360 rev/min
• 3) Rev/min at 18 cm:
– 2650 x 12 =n2 x 18; n2=1767 rev/min
• It should note that the rev/min for empty
package is running faster than full package
2) Belt drive
Flat belt drive
Driven
Driver
Figure 2
Flat belt drive
• If the belt has no thickness, the
surface speed:
• n1 x d1 x pi = n2 x d2 x pi
• If the thickness is t, the surface
speed :
• n1 x (d1 + t) = n2 x (d2 + t)
Question 2
• In Fig. 2, pulley A rotates at 120 rev/min
and has diameter of 30 cm. Pulley B has a
diameter of 50 cm. If the belt is 0.6 cm
thick, estimate the number of rev/min of
pulley B, with slippage ignored.
• Suppose 4% slippage occurred, what is the
rev/min of pulley B?
Answer 2
•
•
•
•
•
n1 x (d1 + t) = n2 x (d2 + t)
120 x (30+0.6) = n2 x (50+0.6)
n2=72.6 rev/min
If 4% slippage, the pulley B will be
72.6 x 0.96% =69.7 rev/min
Vee-belt drive
• The flat belt drive as discussed has the limitation
to the power that it can transmit.
• Owning to the “wedging” effect, the Vee-belt
drive can trasmit four times as much power as the
flat belt for the same cross-sectional area.
• Vee-belt drive is a common transmitting power on
textile machine, e.g from the electric motor to
the main shaft of the machine.
Vee-belt drive
High transmitting power of Vee-belt drive
Question 3
Vee-belt
• The linear velocity of a vee-belt is
1200 m/min. If the pitch diameters
of the motor pulley and machine
pulleys are 16 and 36 cm, calculate
the motor speed and the machine
speed
Answer 3
• Surface speed V= n1 x pi x d1
• Linear speed = speed of pulley
(rev/min) x pi x d1
• 1200 m/min =(n1 x 3.14 x 16)/100;
n1=2385 rev/min. (motor speed)
• 1200 m/min = (n2 x 3.14 x 36)/100;
n2=1060 rev/min (machine speed)
Chain and sprocket drive
• This is a positive drive with a driving
sprocket connected to the driven
sprocket by a roller chain.
• The driving chain from bicycle is an
example of chain-and-sprocket drive.
• It is simple and versatile.
(Rev/min of driving / rev/min of driven)
= (no. of teeth of driven / no of teeth of driver)
Chain-and-Sprocket drive
Question 4
• A sprocket of 24 teeth rotates at 56
rev/min and, by roller-chain drives,
causes a sprocket of 40 teeth to
rotate. Calculate the number of
rev/min of the driven sprocket.
Answer 4
• 56 x (24/40) = 33.6 rev/min.
• One advantage of a chain drive is
that several sprockets may be driven
from one driving sprocket.
• One of these guide sprockets may be
adjustable so that any stretch in the
chain may be taken up.