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Optimisation of drawframe autoleveller
Hitesh Choudharywww.facebook.com/hitesh.choudhary1
Objects of drawframe
What is autoleveller?
It is a online monitering device in spinning process.
It has become an integral part of the spinning process for production of high quality yarn.
It helps in achieving consistent count cv%.
Need of autoleveller
To survive in this age of high competition, it has become necessary to produce an internationally accepted standard yarn quality.
Carded slivers fed to drawframe to drawframe have high degree of uneveness that cannot be tolerated.
Comber contains infamous piecings. Higher CV% affects the appearence of dyed
fabrics by absorbing the dye unevenly.
Norms for CV% at different stages
Material Wrapping length (yards)
Without autoleveller
With autoleveller
Yarn 120 2.5 – 3 1.5 - 2
Roving 15 1.5 – 1.8 0.9 – 1.2
DrawframeSliver
5 0.7 – 0.8 0.4 – 0.5
DrawframeSliver
1 1.5 – 1.6 0.9 – 1.1
Object of autoleveller
To maintain consistent hank of sliver.
Principle: Adjust the Draft continuosly, which will depend on thickness of material fed.
Types of autoleveller
Open Loop Closed loop
Types of autoleveller
Open Loop Closed Loop
This system is effective for short, medium and to some extent long term variations
This system is effective for long term variations
Lack of self monitering Self monitering
More popularly used Rarely used
Servo Drives
Trützschler HSR 1000
Various parts of autoleveller
Scanning roller Signal convertor Levelling processor Servo drive Quality monitor
sensor
Important parameters for quality levelling
Levelling intensity Levelling action point
Levelling Intensity
It indicates the amount of correction to be done.
It is to decide the amount of draft change required to correct feed variation.
The correlation between mass and volume for different fibres is not same.
Levelling action point
The calculated correction should be done on the corresponding defective place.
The time required for the defective material to reach the correction point should be known.
Levelling action point depends on break draft, main draft roller setting and delivery speed
A% test
Sliver weight in ktex
(n-1) slivers n slivers (n+1) slivers
1
2
mean
A% 0
For (n-1) sliversA% = (ktex(n-1) – ktex(n) X 100 ktex(n)
For (n+1) sliversA% = (ktex(n+1) – ktex(n) X 100 ktex(n)
A% + : over-compensation A% - : under-compensation
A% + : under-compensation A% - : over-compensation
Over-compensation: Reduce levelling intensity by A% Under-compensation: Increase levelling intensity by A% Drawframes maintained in good conditions achieve deviation between 0 and 0.5 or between -0.5 and 0
Quick test for levelling action point
a) Levelling action is OK.
b) Levelling action is too late
c) Levelling action is too early
Quick test for levelling intensity
a) Ideal diagram.
b) Under compensation, increase levelling amplification by A%
c) Under compensation, increase levelling amplification by A%
Calibration
Need of calibration:
Calibration is required because even the best instruments drift and loose their ability to give accurate measurements.
On autolleveller callibration is done for Scanning rollers Pressure on scanning rollers Servo motor
Calibration for scanning rollers
Scanning roller current levelling Distance guage
Value
3mm 3.3 V
4mm 5 V
5mm 6.7 V
6mm 8.4 V
For rieter RSB-D30 scanning roller calibration is as follows
Pressure on scanning rollers
Material Scanning roller pressure in KG
Smooth, elastic fibres, Combed cotton 100
Cotton carded 120
High crimp and bulky fibres, such as acrlyic, polyester (W-type)
130
Extremely high bulk, and micro fibres 140
Polypropylene 160
Calibration for Servo motor
1) Calibration servo drive
-25% deviation > yes
target 1487 actual 1486
2) Calibration servo drive
+25% deviation > yes
target 892 actual 890
Trim potentiometer “Tacho” is adjusted in such a way that actual
value equals target value.
Laser based autoleveller
Laser beam is used for measuring the sliver thickness.
LDR is used for sensing the intensity of laser beam.
Fast in response, No fibre rupture, no mechanical parts
High cost
Advantages of autoleveller
All variations are corrected. Count CV% will be consistent. Thin places in sliver and hence in the yarn
will be low. Higher efficiency in further processes.
Conclusions
For obtaining good yarn quality, installation of autoleveller is a must.
As long as the autolevelling system is set properly, advantages mentioned above can be achieved. Otherwise, the negative impact will be very big compared to working without autoleveller
References
RSB D-30 & RSB D-45 manual A project on “ Assesment of autoleveller on breaker and finisher
drawframe” under guidance of Prof. S.D. Mahajan & Prof. M.S. Kulkarni
A practical guide to Combing and Drawing – W. Klien www.textilespinning.blogspot.com Trützschler HSR 1000 brochure Technological study of autoleveller at drawframe on cotton yarn
quality – nasir mahmood, journal of applied sciences, vol 6, year 2006, pages 287-291
Studies on autoleveller in drawframes – M.S.Indradoraiswamy, P.Chellamani, SITRA, 34th Joint technological conference page 13- 19