Investigation of combing forces Part III: Disentangling twisted Fibres —Theory

A mode of the disentangling of two twisted fibres by a combing pin Is presented. It has been postulated that the pin engagement initially increases the twist level and develops torque in the twisted structure in a way similar to the torque generation in the twisting of textile cords. If the pin speed Is not too high, the torque thus developed Is able to untwist the fibres without breaking them, provided lhat the twisted sector is relatively free to rotate. Otherwise, the helix angle ofthc twisted structure increases very sharply towards its geometrical limit, leading to the inevitable consequences of fibre breakage because of buckling or snarling or the twisted structure.The various mathematical formulae derived from this model cat) be used to predict the threshold pin-speed value below which Dbrc breakage could be avoided. They can also be used to examine the effects on fibre breakage of different parameters such as initial twist level, fibre Length, fibre physical properties, etc. The effects or other processing variables, such as fringe density, pin geometry and friction, etc-, can also be inferred from this model.