Kope winder or friction winder ppt

KOEPE WINDER
or
FRICTION WINDER

Historical perspective
German Mining Engineer, Friedrich Koepe invented a
friction winder in 1873 which was later on called as
Koepe winder
In Hannover mine near Bochum in Ruhr Coalfield of
Germany, where Friedrich Koepe was the Technical
Director, winding was required to be done from a lower
level. To save the cost of power, Koepe attached the
cages to an endless haulage rope and dispensed with
the winding drum. He further proposed to have the
motor on the top of the shaft instead of by the side.

Overview of Koepe Winding System
A system where the winding drum is replaced by a large
wheel or sheave. Both cages are connected to the same
rope, which passes around some 200 degrees of the
sheave in a groove of friction material. The Koepe sheave
may be mounted on the ground adjacent to the headgear
or in a tower over the shaft. The drive to the rope is the
frictional resistance between the rope and the sheave. It
requires the use of a balance rope. It is often used for
hoisting heavy loads from deep shafts and has the
advantage that the large inertia of the ordinary winding
drum is avoided.

Schematic figure of a Koepe
winder

(a) (b)
(a): Ground mounted Koepe winder
(b): Tower mounted Koepe winder

Types of friction winders
The friction winders can be categorized as follows:
1. Depending on the location of koepe wheel:
a. Ground mounted
b. Tower mounted
2. Depending on the number of ropes:
a. Single rope
b. Multi rope
3. Depending on the location of head sheaves:
a. Over and under
b. Side by side

Power Calculations
• Power depends upon the torque requirements
• The torques can be classified as:
1. Static torque
2. Dynamic torque
3.Torque required to overcome the friction
Static torque is generated because of the out-of-balance
load. The dynamic torque is required for acceleration
and retardation of masses.

Calculation of Static Torque
• In a Koepe winder, the torques because of the
empty cages, suspension gears, ropes etc. cancel
out each other.
• The torque is required for winding of the mass
of the mineral, which is the only unbalanced
load.
• Requirement of torque is calculated at the
radius of the Koepe wheel.
Torque required
rgMTs  1000

Torque to overcome friction &
Dynamic torque
• The torque to overcome friction can be taken
as some percentage of the static torque (say
18%).
• Total static torque = Sum total of the above
torques
• The dynamic torque depends upon
acceleration and retadation.
• Dynamic torque =
)( nretardatioonacceleratiradialInertiasTotal 

STATIC
TORQUE
DYNAMIC
TORQUE
TOTAL
TORQUE
ta trtc
Torque – time diagram
B’A’
D’C’ B1A1
G’
E’
A2
F’
C2
B2
E2
D2
F2
G2O
A’-B’-C’-D’-E’-F’-
G’
A1-B1
A2-B2- C2-D2-E2-F2-G2

Transmission of power
The koepe wheel consists of sections which are
connected by means of countersunk bolts. The
wheel consists of oakwood/asbestos as a friction
lining all along its rim. The winding rope which
is normally a locked coil rope passes over the
lining. Normally the coefficient of friction
between the rope and lining (μ) is 0.2.
• The friction winder transmits the power of the
electric motor through the friction between rope
and the koepe wheel

Condition of slip
• The rope does not slip over the pulley if

e
T
T

2
1
Where T1 is the tension on loaded side
T2 is the tension on empty side
μ is the coefficient of friction = 0.2 (normally)
θ is the angle of lap = 200o (normally)

• If is greater than 2.0, the rope slips over the
lining and will not be able to transmit the power.
• A friction winder operates under the following
conditions:
a. Capacity of skip: 12 te
b. Mass of skip and suspension gears: 12 te
c. Diameter of rope: 29 mm
d. Mass of the rope: 4.74 kg/m

e

e. No. of ropes: 4
f. Angle of lap: 200o
g. Coefficient of friction: 0.2
h.Depth of winding: 600 m
i. Distance from the top of the skip to friction
wheel: 40 m
j. Acceleration time: 14 s
k.Constant speed time: 28 s
l. Retardation time: 14 s
m. Decking period: 13 s
n. Diameter of koepe pulley: 3500 mm

• Decide whether the system is stable.
• Plot the torque/power- time diagram and
hence find the RMS power.
Assume that the rotating inertias are 96
000 kg-m2.

Calculation for slip condition
• Static Tension on loaded side T1:
Mass of ascending loads =
Mass of loaded skip + Mass of rope
(12000 + 12000) + (640 × 4.74 × 4) = 36134.4 kg
Tension = 36134.4 × 9.81 = 354478.46 N
• Static Tension on empty side T2:
Mass of descending loads =
Mass of empty skip + Mass of rope
(12000) + (640 × 4.74 × 4) = 24134.4 kg
Tension = 24134.4 × 9.81 = 236758.46 N

• Ratio of Tensions =
5.1
46.236758
46.354478

eμθ = e0.2 × 1.11 × 3.142 = 2.01
Since the ratio is less than 2.01, it is acceptable

Calculations for torque
Average speed =
 
sm/28.14
145.028145.0
600


2
/02.1
14
28.14
smLinear acceleration (retardation)
=
RPM of pulley = =
ncecircumferapulley
speedrope
=
500.3142.3
6028.14


77.91

Radial acceleration (retardation) =
2
/58.0
75.1
02.1)(
srad
radiuspulley
nretardatioonacceleratiLinear

Inertia of the masses performing translational
motion:
Total mass of the objects performing translational
motion = (12000 + 640 × 4.74 × 4 + 24000 + 640 × 4.74 ×
4)
= 60268.8 kg
Inertia = Mass × (pulley radius)2= 60268.8 × (1.75) 2
= 184573.2 kg-m2

Rotating inertias = 96000 kg-m2
Total inertia of the system = 280573.2 kg-m2
Total static torque and the torque to overcome friction =
12000 × 9.81 × 1.75 × 1.18 = 243091.8 N-m = 243.09 kN-m
Dynamic torque = Total inertia × radial acceleration
= 280573.2 × 0.58 = 162732.45 N-m
= 162.73 kN-m

Table showing Torque/Power- Time
Time,
s
Static torque, kN-
m
Dynamic torque, kN-
m
Total torque, kN-
m
Power, kW
0-14 243.09 +162.73 405.82 3311.50
14-42 243.09 0 243.09 1983.61
42-56 243.09 -162.73 80.36 655.74
Power = Torque × 2 ×
60
91.77


0
243.09
243.09243.09 243.09
243.09
00
162.73
162.73
0 0
-162.73 -162.73
0
0
405.82 405.82
243.09 243.09
80.36 80.36
0
-200
-100
0
100
200
300
400
500
0 5 10 15 20 25 30 35 40 45 50 55 60
Torque,kN/m
Time, s
Static Torque
Dynamic Torque
Total Torque
Torque-Time Diagram

405.82 405.82
243.09 243.09
80.36 80.36
00
3311.5
1983.81
1983.81
655.74
0
-500
0
500
1000
1500
2000
2500
3000
3500
0 10 20 30 40 50 60
Torque,kN-m/Power,kW
Time, s
Static Torque
Dynamic Torque
Total Torque
Power
Torque/power-Time Diagram

RMS power of the motor =








13
3
1
14
3
2
2814
3
2
)1474.655()2861.1983()1450.3311( 222

Plot the torque- time and power-time diagram for a friction
winder also find the power of the motor for the winder
working under the following conditions:
1. Mass of the loaded skip: 8 te
2. Tare of the skip: 4.5 te
3. Rope mass: 5.78 kg/m
4. Friction wheel dia.: 2 m
5. Rope speed: 8.15 m/s
6. Shaft depth: 350 m
7. Tower height: 30 m
8. Bottom rope length: 10 m

9. Acceleration time: 16 s
10.Constant speed time: 30 s
11. Retardation time: 10 s
12.MI of rotating parts: 24000 kg-m2
13.Torque due to friction: 8% of the torque
due to loaded and empty skips.

Calculations• Static torque: (8-4.5) × 9.81 × 1 = 34.3 kN-m
• Torque due to friction: 0.08 (8+4.5) × 9.81 × 1 = 9.81 kN-m.
• Dynamic torque due to acceleration:
• Acceleration = Max. rope speed ÷ Acceleration time
= 8.15 ÷16 = 0.51 m/s2
• Retardation = Max. rope speed ÷ Retardation time
= 8.15 ÷10 = 0.81 m/s2
• Angular acceleration and retardation are the same as above as the radius of
the pulley is 1 m.

• Mass of the rope: 2 × 390 ×5.78 = 4508 kg
• Total mass: 8000 + 4500 + 4508 = 17008 kg
• Total MI = 41008 kg-m2
• Accelerating torque: 41008 × 0.51 = 20.91
kN-m
• Retarding torque: 41008 × 0.81 = 33.22
kN-m

Table showing Torque/Power- Time
Time, s Static torque,
kN-m
Torque to
overcome
friction, kN-m
Dynamic torque,
kN-m
Total torque,
kN-m
Power, kW
0-16 34.3 9.81 20.91 65.02 1059.83
16-46 34.3 9.81 0 44.11 719.00
46-56 34.3 9.81 -33.22 10.89 177.51
Power = Torque × 2 ×
60
00.2142.3
6015.8










0
65.02 65.0244.11 44.11
10.89 10.89000
1059.83
719 719
177.51 177.51
0
-200
0
200
400
600
800
1000
1200
0 10 20 30 40 50 60
Static torque
Dynamic torque
Total torque
Power
Torque/Power-Time
Diagram

Benefits of Koepe Winder
1. It is most suitable for winding heavy loads from
larger depths. In drum winding the inertia of the
system is high owing to the high mass of the drum
and multilayer coiling of the rope thereon.
2. Koepe winder is simple, light in weight and compact
and that is why its initial cost is low. We do not
require costly foundation etc. for the winder.
3. The inertia of the system is low. The system
demands a low peak power demand from the electric
power supply system resulting in a lower operating
and maintenance cost and a motor of lower HP is
required.

4. Wear and tear of the rope is less as there is no
fleet angle.
5. Multi-rope winding is possible.
6. When the depth of winding increases beyond a
certain depth, the drum winding is possible
only if the drum is replaced by a large size
one. This requires a large size motor also.
However in Koepe winder, you have to change
the length of the rope assuming that the motor
has sufficient power.

7. The cages do not rest on keps rather
they are supported by floating platform
at the banking level. This means that
shock loading of the rope is not there
and kinetic stresses are less. This causes
a requirement of a lower FOS. FOS of 6
to 7 is adequate.

Multi-level winding with two winders operating in the same shaft

Disadvantages of Koepe winding
1. Multi-level winding is not possible in normal course. In
case, it has to be resorted to then:
a. One of the cage has to be replaced by a
counterweight.
b. Two separate winding engines have to be installed in
the same shaft.
2. Generally, it can be used in vertical shafts.
3. It can not be used in sinking shafts.
4. A deeper sump is required for accommodating the tail
rope.

5. Single cage can not be operated.
6. If the rope breaks, both the cages fall in
the pit.

Benefits of Tower-mounted Koepe
winder
1. A larger angle of lap of nearly 230o.
2. Winding rope is protected from weather.
3. Head gears need not be stronger than the
corresponding drum winder.
4. The rope is subjected to a less number of
bends.
5. No hindrance in the winding engine house.

Floating /Hinged/Tilted Platform

Floating /Hinged/Tilted Platform
• In koepe winder, rope stretch takes place, therefore the
above-mentioned is required to be used.
• It consists of swinging rails covered with steel plates.
• The platform is pushed up or down by upcoming and
downgoing cages until it can be in line with the
decking level.
• The platform rails overlap and rest on the cage floor by
at least 35 mm.
• There are two platforms at each entrance of the cage.

Skip Winding
• Skip - A car being hoisted from a slope or shaft.
• The skips are generally constructed of an outer
steel framework which is designed to withstand
loads by the winding system. It also comprises a
removable steel container capable of
withstanding the impact and abrasion during
loading of the mineral. Some times a man riding
deck is provided at the top frames. The area is
calculated at 0.16 m2. To ensure uniform wear on
the guides, the skip is ensured to remain vertical.

Benefits of skip winding• Greater capacity per mine shaft.
• Easy enlargement of hoisting capacity to provide for
expanding production.
• Lower power consumption and lower power cost per ton.
• Lower labor cost per ton.
• For similar outputs, smoother hoisting cycles and lower
rope speeds.
• A larger ratio of coal to gross load hoisted. The ratio pay
load/gross payload is 0.6 for skip and 0.35 for cage.
• Reliability of dumping of coal in tippler.

• The size of cars is independent of that of
the shaft and requirement of number of
cars is also less.

Disadvantages
• More expensive hoisting installations, both in initial costs
and in maintenance.
• Greater breakage of coal, hence less lump.
• Complication in the handling of men, materials, and
waste. Separate arrangements have to be done to
transport men, material and other things like filling
material etc.
• Difficulty of any systematic inspection of coal for
docking.

• Production of obnoxious dust by double
dumping (in some cases, triple dumping)
of run-of-mine coal at the shaft bottom.
• Winding of minerals from different levels
is not possible hence the grades may mix
up. To prevent this large and separate
excavations for each grade have to be
made.

Types of skips
• Bottom-dumping skips:
The important features of these skips are their
comparative simplicity, lightness of construction, quick
dumping, and ready adaptability to handling men,
materials, and mine cars.
• Overturning skip:
Every overturning skip comprises two essential units: the
bucket and the assembled crosshead-bail.

• The bucket is supported by and pivots on a heavy
horizontal shaft that passes through the lower ends
of the bail. A guide wheel is attached to each end
of the bucket near the top and on the outer side.
During the overturning cycle these wheels are
engaged by long angle- iron guides, carefully
curved to provide the correct dumping motion for
the bucket. These guide irons are sometimes
termed the "horns." To effect a prompt, clean
discharge of its load of coal a skip bucket must be
overturned until its side slopes downward 45
degrees.

Loading of the skip
Chute
Anti-
Breakage
Device
Controlling gate
Skip

Loading the skip
• A skip lands at a considerable depth below the floor of a
mine.
• This distance is a function of numerous details of
equipment or practice. One such detail is the height of
the skip. Another is whether or not the coal is weighed in
the mine cars-that is, whether it is weighed before or after
dumping. A third is the type of chutes between the
weigh-pans and the skips when loading is direct. A
fourth detail is whether or not the coal is retained in
storage pockets.

Unloading of skip
• The unloading of skip (bottom
discharge skip) is shown in the video

Section of a Shaft having skip
loading arrangements

• A winding system based on the principles of the Koepe winder. The drive to the
winding ropes is the frictional resistance between the ropes and the driving sheaves.
Multirope friction winders are usually tower mounted, with either cages or skips, and
provided with a counterweight. The sheaves are from about 6 to 12 ft (1.8 to 3.7 m)
in diameter with a direct coupled or geared drive. Four ropes are favored and these
operate in parallel and share the total suspended load. The system was introduced
partly because of the difficulty of winding heavy loads from deep shafts with a single
large-diameter winding rope. Modern winding ropes have become large and heavy,
being 2-1/4 in (5.72 cm) in diameter locked coil, weighing 16.5 st (15 t) for a 1,000-yd
(915-m) shaft; therefore, the introduction of the friction winder, with its
counterweight, and using four smaller ropes side by side in place of one. Such ropes
need be only 1-1/4 in (3.2 cm) in diameter to give equivalent breaking strain.
Source: Dictionary of Mining, Mineral, and Related Terms
•

Kope winder or friction winder ppt

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