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