PROCESS PARAMETERS IN SPEED FRAME - 2
- The roving tension depends on the delivery rate and the difference between peripheral speeds of flyer and the bobbin.
- If the delivery length and the peripheral speed
difference are same, then the tension is ideal.If
delivered length is more than the difference in peripheral speed , then the roving tension will be loose.
If the delivered length by the front bottom roller is less than the difference in pheripheral speeds of flyer and the bobbin, the roving tension will be tight.
- Roving tension can be of three types
- Roving tension at the starting. It depends upon the Bare bobbin diamter and the Cone drum belt position
- Roving tension during build-up. It depends upon the Ratchet wheel and lifter wheel. The difference between peripheral speeds of flyer and bobbin should be same and it should be slightly more than the length delivered by the front roller.
- Roving tension during up and down movement of the bobbin rail should be same. It depends upon the half tooth movement of the ratchet. If it is not exactly half tooth, then the tension will be different during up and down movement of the bobbin rail
- With modern machines, cone drum is removed. Bobbin
speed, bobbin rail speed and flyer speed is determined
by the computer depending upon the tension settings.In
some machines, it can be programmed and the tension
helps to control a bit.In some makes, the tension
setting totally depends upon the sensing by sensors.
The sensing accuracy depends upon the twist cap type, twist cape fixing, oil on top of twist cap etc. If only one roving tension is different due to various other reasons, then the entire machine tension will be altered. This is very dangerous. Enough care should be taken to avoid this problem.
- If lifter wheel is changed, then tension during
build up will also change, the ratchet has to be
accordingly. For a particular roving hank, ratchet wheel depends on Lifter wheel also.
- If the tension is low but unfiorm through out the
bobbin, then the bobbin will be soft. Bobbin content
will also be less. Chances of roving damages will be high.
- If the roving tension is more, then the stretch on
the roving will be more, thin places will be more.
But it is better to increase the TPI little bit and increase the roving tension so that the bobbin content is more, roving damages are less, and creel stretch in the ring frame will also be less, because of higher TPI in the roving.
- It is better to adopt group creeling in speed frame.
Because every piecing of sliver will result in a
thin and thick place. Therefore it is preferable to change 30 upto 60 cans together and remove the sliver piecing from the roving.
- Care should be taken so that no sliver piecing and
roving piecing enters the ringframe and results in yarn.
This yarn always results in thin and thick places from .6 to 2 meters length. This will not be cut by the yarn clearers if the difference in size is less.
- Roving Breaks in speed frame should not be more 1 to 2 per 100 spindle hours.If it is more than that, the reasons should be analysed and corrective action should be taken immediately.
- Spacers should be as small as possible, to improve yarn
quality. If slubs and roving breaks due to
undrafted is more, it would be better to use a bigger spacer(distance clip) instead of increasing the break draft and break draft zone setting to an abnormal level.
- It is better to use good quality apron and rubber cots ,
since the quantity produced by one apron and
top roller is very high compared to ringframe. If the apron breaks and top roller damages are under control,
It is always better to use the best apron and rubber cots available in the market. One should not think about cost saving in this machine. Cost saving for apron and cots can be considered for ringframes.
- Buffing should be done once in 3 months and the top
roller shore hardness is around 80 to 85 degrees.
After buffing, it is better to treat with acid or some special liquids which are being supplied to reduce
- Bottom and top clearers should rotate and should touch the top and bottom roller properly.
- While processing cotton combed material, flyer speed is
very critical. When the bobbin diamter is big,
because of the centrifugal tension, surfact cuts will increase. i.e. roving breaks may occur at presser
or in strand that have just been wound on the top surface of the package. To avoid this problem, it is better to use inverter drive system, to reduce the flyer speed, when the bobbin diameter is big. Otherwise the overall speed should be less for the entire doff, this will reduce the production of speedframe. Sometimes, higher Twist will also reduce the surface cuts.
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