GATE (TF) Textile 2011 Question Paper Solution | GATE/2011/TF/27

Question 27 (Textile Engineering & Fibre Science)

The delivery rate of a roving machine is 20 m/min. Assuming the flyer speed as 1000 rpm, inner diameter of the flyer top as 1 cm, diameter of roving as 2.5 mm, and the slippage between the flyer top and roving as 50%, the false twist (turns/m) in the roving above the flyer is ___________________

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Given in the question-

Delivery rate of roving machine(FRD)=20 m/min

Flyer speed=1000 rpm

Inner dia of the flyer top=1 cm

Dia of roving=2.5 mm
=0.25 cm

Slippage between flyer top and roving=50%

False twist(turns/m) in the roving above the flyer=?

Calculations-

We know-

Surface speed of bobbin=Surface speed of flyer

\pi \times Dia of bobbin x speed of bobbin=\pi \times inner dia of flyer \times rev speed of flyer

\pi \times 0.25 x speed of bobbin=3.14 \times 1 \times 1000

Speed of bobbin=\frac{1000}{0.25}

Speed of bobbin=4000 rpm

Now,

False twist=\frac{Bobbin speed}{FRD}

False twist=\frac{4000}{20}

False twist=200 turms/meter

Becuase there is 50% slippage beween flyer top and roving,then remaing 50% will not slip,so-

False twist=200 x 50% turns/meter

False twist=200 x 50/100 turns/meter

False twist=100 turns/m (Ans)

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