Tension Device

Tension device maintains a proper tension to achieve a uniform package density.
Requirements of tension device:
  1. It must not change yarn twist.
  2. It must not damage the yarn.
  3. It must be cheap.
  4. It must be easily adjustable.
  5. To operating surface must be smooth.
Method of Tension device:
  1. Capstan method.
  2. Additive method.
  3. Combined method.
Capstan Method: The output tension depends on the input tension, co-efficient of friction between the yarn and the post(µ) and the total angle(α).
Tout= Tin*eµα
T2 = T1*eµα
Additive Method: In this system a dead load or spring is used to apply a normal force (N) to change the tension. The output tension is calculated by,
                        Tout= Tin + 2µN
Combined Method: It is combined system of capstan and additive tension. It is device permit the tension level to be raised to any desired extent but it does not permit a reduction in tension.
                        Tout = Tin + Tin eµα + 2µN
                                    Tin ( 1 + eµα )+ 2µN

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