drafting zone of roving/speed/simplex frame machine
Post on 22-Jul-2015
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The roving frame is an intermediate machine between draw frame and ring frame.
The main objective of this frame is to change sliver diameter.
The draft given at the roving frame reduces the linear density of the drawn sliver into a less thick strand of fibres suitable as an input to the ring frame.
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Objects Of Roving Frame-
The main objectives of roving frame are-
The basic function of the roving frame is
attenuation or drafting.
To insert small amount of twist into the
roving.
Wind the roving in a bobbin.
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Drafting
• Drafting is the reduction of mass per unit
length of the sliver.
• In this engine the drafting is very high than
any of other machine.
• The drafting section of the roving frame
may be 3 over 3 or 4 over 4 roller
arrangement.
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• The bottom roller is used always a steel
fluted roller.
• While the top roller is covered with some
synthetic rubber covering.
• The top rollers are pressed down with
sufficient force on to the bottom rollers to
ensure proper grip of the fibres.
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• Three specially designed trumpet guides or condensers are used in the drafting section of the machine.
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• In the modern roving frames a double apron
system is provided at the middle pair of
drafting rollers.
In the roving frame we can witness
three drafting zones.
1. Break draft
2. Main draft
3. Tension draft
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The draft at the back zone is called as break
draft.
The main objective of the break draft is to
enhance the fiber orientation instead of
drafting itself.
In main draft the drafting execution take
place. But for an optimum draft the fiber
orientation is very important factor.
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Main draft is the drafting zone where the real
drafting is taken place.
• In here a draft in high magnitude is taken
place.
• For good fiber control many methods are
used such as aprons, pressure bars.
• The total draft is the product of break and
main draft.
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3. Tension Draft-
• The main objective of the tension draft is to
visualize better and adequate tension to the
sliver.
• In this zone the finer count for the roving
frame is already achieved but after freeing
from front roller twist has to be inserted.
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