DRUM WINDING
There are four different shapes of Drum used in India these are
A)Cylindrical Drum.
B)Conical Drum.
C)Cylindro-conical Drum.
D)By-Cylindro-conical Drum.
CYLINDRICAL DRUM
A Cylindrical or parallel drum is a simple and robust in construction.
The winding ropes are attached at the end of the drum barrel, and arrange to coil on the drum in the opposite direction, so that when the drum rotates one cage will be raised and other lowered.
The rope coiling underneath the drum is called under lap.
The rope coiling over the top of the drum is the overlap.
It may be either grooved or plain.
Its serious drawback is that, it can be used for shallow shaft only.
In winding from deep shaft, the weight of one winding rope will exceed the weight of the coal raised per wind.
Thus there will an excessive load on engine when starting and negative loads towards the end of the wind causing heavy brake wear.
This unbalancing of load in cylindrical drums can be reduced by tail ropes.
The advantage of using tail rope is that
only load against the engine will be the constant load of coal raised, resulting in better control of engine and reduce power consumption .
But the use of tail rope has the following disadvantages.
A)The total masses to be accelerated and decelerated are increased.
B)Extra cost of tail rope is incurred.
C)Weight on Capel is increased.
CONICAL DRUM
It is provided with flanges of two sides of the conical portion for even coiling of rope.
Rope supporting the full cage is coil on the small radius and that holding the empty cage on large radius at the commencement of the wind.
These portion are reserved at the end of the wind.
A conical drum has the following advantages.
A) No tail rope is required.
B)At the commencement of the wind, torque against engine, leaving the engine to accelerate the moving masses and to overcome friction.
C) At end of wind, instead of negative load there will be a positive load because the descending rope has now come on small diameter, reducing its torque while the ascending rope, is on large diameter and its torque correspondingly increases.
The serious disadvantage of the conical drum is that only the half width of drum can be used for coiling at each rope.
Hence for deep shaft a huge size of drum will be required which may prove prohibitive proposition.
CYLINDRO-CONICAL-DRUM
This is an improvement upon the conical drum in which the apex of conical portion is provided with cylindrical drum.
This is a combination of cone and a cylinder.
The ascending rope is wound on the smaller diameter of the cone at first, and as the engine reaches full speed after the period of acceleration the rope is wound on the larger cylindrical part.
For dip shaft the rope is wound back on itself for the last part of the hoisting period.
The double winding materially reduces the total width of the drum.
A cylindro-conical has the following advantages.
A)The conical section improves the balance of system at the beginning of the wind when the difference between the static torque due to suspended load is greatest.
B)The parallel or cylindrical section provides for additional space for coiling of ascending rope, provided that the fleet angle ration is less than 1 in 40. is the condition is not obtained, additional capacity of the ropes on parallel portion can be provided by fitting a center plate to the drum and adopting double layer coiling.
The main disadvantage is that the design is not so simple and the operation is not so smooth.
BY-CYLINDRO-CONICAL-DRUM
It is composed of two cylindrical section, one of the small diameter, the other of large diameter, joined by a conical section or scroll of the uniform or variable pitch.
At the beginning of the hoisting period the loaded rope is wound on the smaller cylinder until the full speed is attained, when the rope is transferred by the cone or scroll to the large diameter.
Near the end of the hoist but just before the beginning of retardation, the descending rope is transferred from the large to the small cylinder.
The design of electric motors is largely controlled by the heating effect due to the hoisting cycle.
Heating is proportional to the square of the current passing through the motor and time it lasts.
Since the torque of the motor is proportional to the current, the high starting torque entails a strong heating effect and the motor must be large to properly dissipate the head produced.
The bi-by-cylindro-conical drums serves to keep the heating effect of hoisting cycle below that of the cylindrical drum.
It reduces the peak load on the motor and lands itself better than any other type of drum to a more definite control of torque especially during the starting torque.
A bi-cyindro-coical drum suffers from the following disadvantages.
It is heavier and more expensive than a cylindrical drum.
It cannot be used for multideck cages for simultaneous decking.
For deep winding the drum size becomes excessive.
Rope lying on conical portion may occupy more space than parallel sided drum and they may cause trouble due to angle of fleet.
WATCH VIDEO
DRUM WINDING
TO WATCH MORE MINING RELATED KNOWLEDGEABLE VIDEOS
CLICK ON BELOW LINK
Comments
Post a Comment