Rieter

Balloon tension

Index

The yarn tension in the balloon (FB ) is the tension which finally penetrates almost to the spinning triangle and which is responsible for most of the thread breaks in practice. It is reduced to a very small degree by the diversion of the yarn at the thread guide. An equilibrium of forces must be obtained between yarn tension FF and balloon tension FB. Since the yarn is diverted at the traveler and friction arises there, this equilibrium is given  [20] by:

F_F = F_B \times {e^{ \mu \varepsilon}}

where e is the base of natural logarithms (2.718), μ is the coefficient of friction between the yarn and traveler, and ξ is the angle of wrap of the yarn on the traveler. The value of eμξ generally lies between 1.2 and 1.8. The balloon tension FB is therefore a little more than half the winding tension (FF).

Yarn tension FV (Fig. 99) at the point of maximum diameter in the balloon can be derived approximately from the following formula given by Professor Krause:

F_V = k \times {\omega^2}_L \times {H^2} \times \sigma

where ωL is the angular velocity of the traveler, H is the height of the balloon, σ is the specific mass of the yarn, i.e. (yarn mass/yarn length)≈tex, and k is a constant. Thus, for a given yarn count, the yarn tension in the balloon is strongly dependent upon the traveler speed and the height of the balloon. High traveler speeds, and greater balloon heights, lead to very high yarn tensions in the balloon.

Fig. 99 – The balloon tension